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the CGM-101 Manual - Syscomp Electronic Design

1. Digital 1 0 al Inputs WeES4a 2 Vo HN Digital Outputs y ascacaaa l J RMAA 5 5 DMM2 02 Skypesetu Op A start 8 Electrical Engineering We 1 C Documents and Settin gt Syscomp CircuitGear Mini E Syscomp CircuitGear Mini p2 Syscomp CircuitGear a lt BO Hago 12 22PM Figure 1 The CGM 101 Graphical User Interface 1 Overview The Syscomp CircuitGear Mini CGM 101 is a combination of three electronic instruments a two channel digital storage oscilloscope a waveform generator and a digital input output port Host software can operate the instrument as a spectrum analyser and as a vector network analyser Bode plotter CircuitGear includes a small hardware module and display software that runs on a host PC Figure 1 shows the user interface The CGM 101 is a development based on the successful CircuitGear CGM 101 with many enhancements and additional features 1 1 Oscilloscope The oscilloscope is a dual channel 2MSample sec oscilloscope with 12 bit A D conversion digital storage and display Channels A and B are sampled simultaneously and stored in the oscilloscope memory before being sent for display to the host computer Consequently the signals are always time aligned and associated with the same trigger signal Triggering is accomplished by digital circuitry so it is precise and consistent Trigger controls inc
2. Windows Installation cesser E A A A oe ee 8 17 2 Macintosh Install vom rior ES ee we oe we a See ES 17 2 1 Checking the Host Machine 0 00 00 0000 0000004 17 2 2 Installing Software i 546 454 4 600 54 bee ean aut beeea cede a a 17 23 Installing Diver sa maie a eee a oo a ea BP GR A we ol A Be Se 17 3 Linux Installation 3 2 545 054 00484 500k a cb b as eee sw eee se ee 17 3 1 Hardware Installation css ee E RSS OG eh PE Se Se eS 17 3 2 Optional Running the GUI from Source c seo e ecs reeset e tahu repet Troubleshooting 18 1 Overview of USB Operation os scce ca caso wuwa ti se eaa aa ee ee 18 2 Microsolt Windows s e ers g ei ek Re da a OE Bw O a 18 2 1 Manually Assigning a COM Port Number in Windows XP 18 2 2 Checking the Installed Files 2 2 ee a a 18 2 3 Obtaining Details of the USB Serial Port 2 ee o e 18 2 4 Windows 7 Notes 2 24 5 4 4 eas 2 ead 6 OSS Che ee Eee eS Bad ee 21 22 22 23 23 24 24 25 25 26 26 27 27 28 28 29 29 30 18 3 LINUX Ceac di Asa cen Bas a a Be woh ace oe BRS REDS 48 18 3 1 Manually Changing Device Port Permissions o e e e 49 18 3 2 Setting Default Port Permissions to User Mode Suse9 2 50 18 3 3 Setting Default Port Permissions to User Mode Suse 10 3 50 18 3 4 Setting Default Port Permissions to User Mode FedoraCore6 51 18 3 5 Running the Programi
3. Figure 12 shows a screen shot of a VNA plot of a single pole RC lowpass filter Figure 11 shows how the test circuit must be wired Notice that there is no internal connection between the generator output and the channel A input The instrument grounds are connected internally so only one ground wire is required to the external circuit To measure the impedance of some other two terminal device such as an inductor or loudspeaker connect it 21 Scope Channel B Input in place of the capacitor in figure 11 Choose the resistor to be larger than the maximum impedance of that com ponent Then in effect the device is driven by a constant current and the voltage across the device is proportional to its impedance The display of figure 12 is the amplitude and phase response of a small 1 1 audio transformer The primary was driven by the generator and connected to Channel A The secondary was connected to Channel B Notice that the amplitude response rolls off below 20Hz and exhibits very substantial peaking around 300kHz This shows up as ringing in the square wave time domain response The transformer midband phase response because the transformer primary and secondary are deliberately wired out of phase The jump in the phase response from 180 to 180 is correct plus or minus 180 degrees is the same physical result e Two slide controls set the start and finish frequency e A third slider sets the frequency step The frequency step is
4. Find the file et c group Probably read write permission is disabled for users on this file as well Make a note of the permissions because we ll change it back For example ls 1 etc group rw 1 root root 934 2008 05 22 10 17 etc group In order to edit it change the permissions to allow any user to edit that file using the command sudo chmod 777 group lt your password here gt ls 1 etc group rwxrwxrwx 1 root root 954 2008 10 24 22 02 etc group Now you can edit and save the file Load that file into a text editor Find the line with dialout in it If the line ends in a colon that means that no one yet belongs to this group Add your login name If there already is some other login name add a comma and then your login name Here s what it might look like with me peter added to the dialout group after gabe man x 12 proxy x 13 kmem x 15 dialout x 20 gabe peter faxsx e244 voice x 22 and so on Save the file Reboot the computer Execute the groups command You should see that you are a member of the dialout group groups peter dialout 53 Now you should be able to start the instrument code by executing wish main tcl in the directory where main tclis located The instrument should find and connect to the USB port For security you may want to return the permissions on etc group as they were originally as you noted previously In my case giving groups and users read permission a
5. 10 Solution The sample rate is 200kS sec The sample interval AT is the reciprocal of this 1 200 x 103 5 pSec AT The number of points N in the data record is 512 points so the total length of the data record is T NAT 2 56 mSec The resolution Af is the reciprocal of the record length APs T 390 625 Hz For example the 7th harmonic should appear at f7 70kHz The spectrum display actually puts it at 70313 Hz which is bin 180 Fz 180 x 390 625 70313 Hz The maximum frequency fmax On the display occurs at bin 256 100 kHz 8 3 Spectrum Display Cursor Control For fine control over the spectrum frequency readout the left and right cursor buttons on the keyboard move the spectrum display cursor one pixel to the left or right 19 8 4 Spectrum Weighting Functions Weighting or window functions are often applied to the time sequence data prior to transformation into the fre quency domain All window functions taper the data down to zero at its ends Then the discontinuity caused by a finite record length does not affect the shape of the transform The choice of window function depends on the application and all window functions are a compromise of some sort For example some window functions provide very accurate amplitude readings others are best for separating closely spaced frequencies A collection of window functions is shown at http en wikipedia org wiki Window_function The current
6. Analysis FFT X Y Plot Data record to CSV file oscilloscope and VNA plot Save Load Settings Cursor Readouts Auto Measurements Vertical Calibration Offset Calibration 0 1Hz to 200kHz 8 bits at all amplitude and offset settings Sine Square Triangle Ramp Arbitrary 8 bit resolution vertical 256 time points Constructed with Wavemaker software Output Waveform Amplitude 2 5V Amplitude Control Hardware Output Offset Control 2 5V Offset Control Hardware Vertical Resolution Output Impedance 150 ohms Waveforms Arbitrary Waveform Digital VO Output 8 bits GUI Graphical User Interface controlled 5 volt HEMOS 8 bits GUI indicators 5 or 3 volt HEMOS Variable frequency 1Hz to 125kHz in steps of 1Hz Variable duty cycle 0 to 100 in steps of 1 Input Pulse waveform Other Indicators Power LED Green Activity LED Red Interface USB 2 0 Emulated serial port Physical Dimensions 8cm W x 2 4cm H x 12 5cm D 3 lin W x lin H x 5in D GUI Source Code Tcl Tk language Open source OSI Compliant Windows Linux Mac operating systems Current Consumption Scope Only 230mA to 260mA 4 Installation and Operation Once the software is installed and operational starting the CGM 101 is a matter of plugging in the hardware to a USB port and clicking on the software icon or executing a command line instruction This applies to all operating systems Windows Mac OS X Linux The installation proce
7. GUI to manually connect to the serial port we found using dmesg eg dev tt yUSBO 5 The GUI should indicate Connected and the oscilloscope trace should show activity Note that currently Linux assigns USB serial ports in the order in which the instruments are plugged in You may have to manually reassign the port settings in the GUI intrumentation software if multiple usb serial devices such as Syscomp Instruments are used simultaneously Use dmesg each time you attach an instrument to the computer to determine its serial port assignment 17 3 2 Optional Running the GUI from Source You can execute the source code directly using the Tcl interpreter wish See section 15 on page 37 For infor mation on the Tcl language see the application note on the Syscomp website Hello Button 18 Troubleshooting 18 1 Overview of USB Operation In general the operation of the USB connection is seamless and invisible to the user Operation of the oscilloscope is usually as simple as plugging it in to an USB port and running the oscilloscope GUI software However it may be useful to understand some of the details The USB interface uses a USB Serial chip FT245BM from FTDI This chip with the appropriate driver software on the host PC emulates a serial port Consequently the Tcl Tk GUI software can access the hardware just as if it was accessing a device connected to the host serial port This is orders of magnitude simpler than dealing with USB whic
8. Net The digital controls supply the functionality of a digital Exerciser Unit which can apply a stimulus to a digital circuit and measure the output For example the 8 bit digital lines can be used as inputs and indicators for a logic net Students set up various combinations of input signals to the net and record the outputs to generate logic equations or a truth table for the logic net State Machine Exerciser A single manual output line and the PWM output can be used as a pulser for counter and state machine circuits The manual output exercises the circuit at low speeds where the be haviour can be observed on the GUI indicators The PWM output is then used to operate the circuit at higher frequencies and the oscilloscope can be used to observe faster events Mixed Analog and Digital Circuits The digital outputs control a MDAC multiplying D A converter which sets the centre frequency of a bandpass filter The generator and oscilloscope function as a Vector Network Analyser showing how the frequency response changes as the digital value is adjusted Switching Power Supply The PWM output controls a power MOSFET and LC network which functions as a simple switching power supply Similarily PWM output can modulate the power to a DC motor as a simple method of speed control PWM DAC It is common for the PWM output of a microprocessor to be used as the basis for a low cost digital analog converter The PWM signal is filtered to produce a variabl
9. With the VNA operational select Tools gt Export Waveform CSV 9 1 Phase Display When the phase is close to the top or the bottom of the display small phase changes can cause it to jitter in an annoying fashion from one limit to the other For a signal that changes over a wide range of phase this cannot be entirely prevented However it can be reduced by adjusting the vertical scale of the phase display By default the phase display ranges from 180 to 180 with 0 in the centre To change this place the cursor in the phase plotting area and right click A menu appears allowing the selection of a different phase display arrangement 360 to 0 for example 9 2 Linear and Narrow Band Sweep It is possible to set the analysis to a narrow range of frequencies to characterize narrow band filters and piezoelec tric crystals e Click on the numeric readout for Start Frequency An entry window appears Enter the starting frequency in Hz e Click on the numeric readout for End Frequency An entry window appears Enter the ending fre quency in Hz 22 e Click on the numeric readout for Frequency Step An entry window appears Enter the amount by which the frequency increases for each measurement This value must be greater than the minimum fre quency step for the waveform generator which is 0 1Hz e Both Logarithmic and Linear sweep will work but the Linear Sweep setting allows more precise control of the displ
10. character 0 Sine 1 Square 2 Triangle 3 Sawtooth 4 Custom aA WCXXXYYY Load a custom waveform sample into the device buffer Each custom waveform is 256 samples long consisting of 8 bit samples XXX is the sample index 0 to 256 YYY is the sample value 0 to 256 Daal Output buffer Applies the custom waveform buffer to the waveform generator output Description Detail wx Saves the current custom waveform to non volatile memory Read Waveform Reads the current waveform Returns RWSOS1 S255 where RW are ascii characters SO is the first sample byte S255 is the last sample This command returns 258 bytes 14 Manual Operation The oscilloscope may be operated by sending it commands from a terminal emulator If you are creating new software to control the hardware this can be useful for debugging 14 1 Windows The Hyperterminal program that is supplied as part of Windows operating systems previous to Win 7 is suitable for this 1 To simplify matters it is probably best to unplug any USB devices that are connected 2 Plug the scope hardware into a USB port on the computer 3 Using the steps described in section 18 2 1 determine the COM port that the scope is currently connected to 4 Start Hyperterminal Start gt Programs gt Accessories gt Communications gt Hyperterminal Hyperterminal starts with a Connection Description popup window Cancel the popup Select Fi
11. click on Install Otherwise click Back and revise the necessary entries The Installing screen and progress bar of figure 18 f appears Wait while that completes The USB Device Driver install screen of figure 18 g appears Click Next 10 LI The Installing drivers screen of figure 18 h appears The Congratulations You are finished installing drivers screen appears figure 18 1 Click Finish The Completing the Syscomp Setup Wizard screen appears figure 18 7 Click Finish The software is installed 39 i Setup Syscomp CircuitGear 15 xi Welcome to the Syscomp CircuitGear Setup Wizard This wil install Syscomp CircuitGesr 1 13 on your computer Itis recommended that you close all other applications before continuing Click Next to continue or Cancel to exit Setup a Welcome to Setup Wizard sur syscomp CroutGcor AA Select Additional Tasks Which additional tasks should be performed y scomp CircuitGear ioj x Select Destination Location Where should Syscomp CircuitGear be installed Syscomp CircuitGear lol x Select Start Menu Folder Where should Setup place the program s shortcuts tJ Setup wil install Syscomp CircutGear into the folowing folder To continue click Next If you would like to select a different folder click Browse Browse Atleast 31 6 MB of free disk space is required Setup will create the program s short
12. command consists of an ascii string of characters such as T55 lt cr gt to set the trigger level to 55 where lt cr gt is a carriage return character If you are running under a Windows operating system in addition to the material in the user manual you can see commands being sent to the oscilloscope by selecting View gt Debug Console This brings up a terminal screen which lists commands as they are being sent to the scope hardware and some other debug information If the operator starts the program from a terminal window executing a command like wish main tcl then the terminal window becomes the console This information scrolls past rather quickly when the scope is in auto trigger mode because it is repeatedly obtaining data from the hardware To slow this down put the scope in Manual Trigger mode Now each time you hit the manual trigger button the debug screen will show the commands that were sent to the scope hardware Now you can change control settings on the scope GUI and see the corresponding commands as they are sent to the scope hardware For example move the trigger level cursor on the scope screen and you will see a series of trigger level commands being sent to the hardware Similarily changing the vertical preamplifier gain settings to show the corresponding hardware commands Regarding the oscilloscope operation For normal triggering the host PC issues a request for an update When a trigger occurs the
13. cs uk risas he Seow abe eyes 51 18 3 6 Ubuntu Linux Install e 52 18 3 7 64BIT LINUX ss suomaa eR Bee RA a a eR i 54 18 3 8 Running under 64 bit Sidux Debian based Linux o o e 54 18 3 9 Device Properties using usbview ee a 54 18 3 10 Terminal Connection under Linux e 55 18 4 Macintosh Lab st aes ea als Siete ra le a a as ale a O 56 19 Sources of Information 57 191 NewS GrOUDS ve opor EEE ware eee ee Pewee 57 19 27 Websites e o oder sd el a e weds y aedas 57 WSs Paper es a A a RO AAA AAA 57 194 MEXIDOOKS i a a Baw SES de we ES A A rd ds Ed BS oe 57 List of Figures 1 The CGM 101 Graphical User Interface o o e e 2 2 Oscilloscope GUL repes e pe tepip dre a oho G de 6 3 Enlarged Screen aad da ea ed Sheed ed 8 4 Trigger Cursors sa lt 6 pS AAA Be RE We Be Gd 10 5 Measurements Screen 144 444 e ons BS Se oe OW ee ed E 11 6 XY Display Modes s sos e peere dar 422820 a be eee Peete he ws eee ee ee 11 7 Diode Voltage Current Characteristic 2 ee 12 8 Generator Conttols say gia se eae AMG RG SDS ee A Re Re RE ek eR ES 14 9 Digital Controls e s lt e eoep sae WEG SE ee eee ee a ewe A 16 10 Square Wave Spectr s scuds eS GOR eee Bn Be a a e A OR Be Se a 18 11 Network Analyser Wiring 2 cocasses orede ntaa aare reassa 21 12 Vector Network Analys t saso See aaa a a e e a ae da 21 13 CGM Mini Rear Panel Connector Pinou
14. hardware acquires the waveform and sends it to the host The host receives it on an asynchronous basis using the fileevent command That command then processes the data Debug Level If you d like to see more detail of the commands being sent to the hardware you can turn on a debugging flag in the software Here s the way to do that on a Windows system e Open the source file directory which is something like C Program Files Syscomp CGR101 1 17 source e Load the file main tcl into notepad 29 e find the line near the beginning of the file that says set debugLevel 0 Change this to set debugLevel 1 Save the file e Run the Syscomp software Select the menu item View gt Debug Console e A new window will appear which shows the commands being sent to the scope The scope is on Auto triggering by default Change this to normal triggering to stop the scrolling The window shows only commands being sent to the scope not the data being returned If you need that modify the source code with print statements for the quantities of interest 13 2 CircuitGear Mini ASCII Command Set For setup of the a terminal emulator to send these commands see section on page All commands must be terminated with newline lt 0x0A gt character In the following commands the spaces are real and must be part of the command string General i Info Identify Returns an identification string and the firmware revision xSyscomp CircuitGea
15. integer Timer period is YYYY x32 mu sec Command Manual Trigger Causes a manual trigger Command T XXXX Set trigger level Sets the trigger level XXXX is an integer between 0 and 4095 The trigger integer Ntrigger 18 calculated as follows Nerigger Nof fset gt c where Virigger 18 the trigger voltage in volts Nog fset 18 the calculated offset see Adjust channel offset above Step is the A D converter step size 0 025 for the high input range 0 002481 for the low input range Description Detail Command Description Falling trigger Sets trigger slope to falling Command Detail Rising trigger Sets trigger slope to rising Command Detail Trigger A Select channel A as trigger source Command Detail Trigger B Select channel B as trigger source Command Detail External Trigger Select external trigger source 32 a internal Trigger Disable external trigger source Digital I O Port O XXX Set output Sets digital output to XXX XXX is a byte corresponding to the output bits Examples Set all output bits high O 255 Set all output bits low O 0 Oh zero Set only bit zero high O 1 Set only bit four high O 16 Description Description Read Input Returns the digital input state as TX where T is an ascii character capital letter eye X is a byte representing the current state of the digital inputs Auto digital input Sets the sampling period for automatically reading the digital in
16. not in use in order to reduce screen clutter Invert This selection inverts the display This is most useful in conjuction with the Add waveform display Inverting one channel and adding the two inputs creates a display of the difference between the two signals Probe x1 x10 x100 These settings adjust the vertical scale factor to match the scale factor of the probe For example if you are using a x10 setting on the oscilloscope probe and select x10 in this control the displays and screen scale factors will change appropriately 5 2 Oscilloscope Mode Timebase The timebase has two modes of operation oscilloscope mode and stripchart mode Oscilloscope mode is most suitable for displaying rapidly changing events For example it is possible to capture and display the transient voltage from the closing of an electromechanical switch Stripchart mode is suitable for recording slowly changing events It mimics the behaviour of old fashioned pen recorders that were used for recording such phenomena as earthquake waves or changing temperature The timebase changes automatically from oscilloscope mode to stripchart mode at the timebase settings 100 to 200mSec per division During oscilloscope mode the timebase interval shows Sampling to indicate that a sampling oscilloscope is in operation During stripchart mode the timebase interval shows Scan In oscilloscope mode the trigger functions section 5 4 are operational On the occur
17. or Fourier Analysis is the process of analysing some time domain waveform to find its spectrum We also say that the time domain waveform is converted into a frequency spectrum by means of the Fourier transform Clicking on Tools gt Spectrum Analysis brings up the spectrum analysis display of figure 10 The displayed spectrum in this image is a 10kHz square wave The theory of Fourier Analysis shows that a square wave is composed of a fundamental of magnitude E volts at frequency f 10kHz in this case with the following harmonics 3 magnitude at frequency 3f 7 5 magnitude at frequency 5f E 7 magnitude at frequency 7 f and so on The spectrum display shows this pattern Each vertical line represents one of these frequency components The height of the line is proportional to the magnitude of that particular component The horizontal axis is a linear scale of frequency with zero frequency DC at the left edge The vertical cursor can be dragged horizontally to determine the frequency and magnitude of a component of the spectrum The spectrum display and main waveform display are active at the same time allowing one to simultaneously observe a waveform in the time domain and frequency domain 8 1 Interpreting the Spectrum Analyser Display Because of fundamental limitations in a sampled data system it is possible for the display to be misleading Here are some important points to keep in mind when using spectrum analysis based on digital
18. port something like tt yUSBO or tt yUSB1 and so on Under Mac OS X the FTDI driver may or may not be present If the Syscomp software will not connect to the hardware the first step should be to download and install the appropriate driver from the FTDI website at http www ftdichip com Drivers VCP htm Notice that the same FTDI driver works for all versions of OS X In Mac OS X the assigned USB Serial port is a device named cu usbserial xxxx where xxxx is some serial number Otherwise the USB Serial port assignment is similar to Linux 18 2 Microsoft Windows 18 2 1 Manually Assigning a COM Port Number in Windows XP It may be useful to know how to set the COM port manually For example under certain circumstances it is possible for the operating system to assign a low value COM port that conflicts with some other non Syscomp device COM values COM1 COM2 and COM3 are risky to use Then if the device is assigned to COM3 for example and is not connecting properly you should try moving it to another COM port number such as COM9 We know that certain Bluetooth devices have caused this problem in the past All COM port values up to COM99 should work correctly l Ze Plug in the problem instrument to a USB port Go to Start gt Settings gt Control Panel gt System gt Hardware gt Device Manager Double click on Ports COM and LPT This opens to show any USB serial port assignments Let s say that it sh
19. section 13 on page 29 On a netbook computer the digital controls run off the bottom of the screen The digital I O controls are in their own window and can be moved somewhere convenient or minimized 7 1 8 Bit Digital Output Clicking on an individual Digital Output button bit causes the corresponding bit to illuminate on the GUI and the corresponding output line to go into the high HIGH state Clicking again causes the bit to extinguish and the corresponding output line to go LOW The available current to a USB device is 500mA maximum and this current must operate the oscilloscope and signal generator as well as the digital circuitry Consequently the digital drive current is very limited a few milliamps per output Load devices such as high current LEDs or DC motors will require their own power supply 7 2 8 Bit Digital Input The GUI digital input indicators illuminate when the corresponding input level is a logic HIGH The logic levels may correspond to 3V HC logic or 5V HC logic Great care should be taken not to exceed 5 volts on any input Inputs are buffered but all devices are surface mount soldered so they are not trivial to replace 7 3 PWM Pulse Width Modulated Waveform The PWM output available on the rear panel connector is a 5 volt pulse The duty cycle is continuously adjustable withthe Duty Cycle slider over a range of 0 to 100 The output frequency is set by the Frequency slider over a range of 1Hz to 125kHz T
20. step size 0 025 for the high input range 0 002481 for the low input range Command Changes the timebase sampling rate were n is an ascii character as follows 500ns div to 20us div 2MHz sampling rate 50us div MHz sampling rate 100ys div 500kHz sampling rate 200us div 250 kHz sampling rate 125 kHz sampling rate 500Ats div 62 5 kHz sampling rate 1ms div 2MHz sampling with subsampling 2ms div 2MHz sampling with subsampling 5ms div 2MHz sampling with subsampling 10ms div 2MHz sampling with subsampling 20ms div 2MHz sampling with subsampling 50ms div 2MHz sampling with subsampling 100ms div 2MHz sampling with subsampling 20ms sample strip chart mode SOms sample strip chart mode 100ms sample strip chart mode G 200ms sample strip chart mode H 5000ms sample strip chart mode I 1s sample strip chart mode J 2s sample strip chart mode Command Detail D AIB DC Coupling Selects DC coupling for channel A or B 0 1 2 3 4 5 6 7 8 9 A B C D E F Command Detail A A B AC Coupling Selects AC coupling for channel A or B Command P AlBlalb Selects preamp range setting A Channel A high range B Channel B high range a Channel A low range b Channel B low range Description Command Description Detail Enables auto triggering Command Deal Disables auto triggering Command a YYYY Auto period Sets the auto trigger timer YYYY is an
21. syscompdesign com download htm Use the mkdir command to reate a directory on your computer In my case this directory is home peter eelab Click on the file Linux x86bin to download it to your computer check that it is in the ee lab directory figure 24 The file that you downloaded is an archive from which you must extract the files Right click on the file and selectExtract Here A directory is created with the extracted files in it Change to that directory and examine the contents figure 25 Check that main tcl is present in the file list This is the file to execute to start the oscilloscope program Check that the Tcl Interpreter wish is present on your machine which wish If wish is present the which command will show the directory usr bin wish Since usr bin is usually on your PATH wish is present and should execute Now you can execute the DSO 101 software with the command wish main tcl However the oscilloscope software will not connect properly to a USB port until the permissions are corrected That s the next step Configure Permissions on the USB Ports Plugging a Syscomp oscilloscope waveform generator or CircuitGear unit causes the system to create a serial USB port at dev ttyUSBO Notice that this is yew ess bee zero not yew ess bee oh If you have another 52 E 13KB CS File 22 05 2009 11 36 AM E 13KB CSV File 22 05 2009 11 37 AM E 13KB CSV File 22 05 2009 11 37 AM E 13KB CSV File 2
22. takes for that trigger signal to occur In the Single position the scope waits for a trigger signal This is known as the Armed state When a trigger signal occurs the software captures and displays that waveform and disables further triggers The Single Shot Reset button clears the display and returns the scope to the Armed state e Manual Trigger Actuating this button generates a trigger signal This is sometimes useful to cause the scope to capture one waveform e Trigger Options The Options trigger menu leads to the following controls Trigger Source The trigger signal may be derived from the Channel A waveform or the Channel B waveform Gener ally it is easier to obtain a stable trigger signal from the simpler of the two waveforms Trigger Slope The trigger slope control selects a positive going or negative going slope at the trigger point This allows one to trigger off the leading or trailing edge of a positive pulse waveform for example An slope symbol on the GUI in the Trigger area shows the currently selected slope e Trigger Hysterysis Display Noise on the triggering signal can cause mis triggering and jitter To prevent this there is a hysterysis band associated with the trigger level T Referring to figure 4 the hysterysis band is defined by an upper IS File View Tools Hardware Help Comnerted Triggered Manual Trigger Trigger Mode Normal Eg si
23. that establishes the trigger point In order to cause triggering the triggering waveform must cross through the trigger cursor level As the trigger level cursor is dragged an accompanying readout displays the trigger level in volts e Trigger Mode Auto Normal Single In the Normal position the scope hardware must get a proper trigger signal in order to display a new waveform Without a trigger signal the display simply waits The Manual Trigger button can be used to force a trigger event that is display one capture In the Auto position if there is a trigger signal the scope uses the trigger signal to synchronize waveform capture If there is no trigger signal the scope hardware waits for a period of time and then generates a trigger signal internally That way there are periodic updates to the waveform display even if triggering is not occurring from an input waveform In general the most convenient position is Auto However there are two situations where Normal triggering is necessary For very low frequency waveforms the trigger signals occur infrequently If Auto triggering is enabled the scope will decide that trigger signals are not present and generate them internally This is not what is wanted the scope should wait for a waveform trigger signal Ifthe scope is being used to capture a single shot event then it should not trigger itself it should wait for a waveform trigger signal regardless of how long it
24. the Tcl Tk program The wish program which is the interpreter for all Tcl Tk programs is not being found by the operating system Locate it and change your path so that it is found The device is being recognized and connects properly but does not respond properly to certain controls Use the instructions in section 14 3 to send commands to the hardware to determine how it is functioning Check the kernel version The drivers for the FTDI USB Serial interface are a standard part of the Linux kernel from version 2 4 onward To check that you have a sufficiently modern kernel run the dmesg command piped to the more command phiscock panther dmesg more Examine the first few lines which should be something like this Linux version 2 6 8 24 default geeko buildhost gcc version 3 3 4 pre 3 3 5 20040809 1 Wed Oct 6 09 16 23 UTC 2004 In this case the kernel is 2 6 8 24 so it contains the FTDI drivers If your kernel version is older than version 2 4 you may have to upgrade the kernel or install a driver module Install the software per the instructions shown in section 17 3 on page 42 Determine the serial port used by the USB driver In this step we ll use the dmesg command to determine which serial COM port is being assigned to the oscilloscope when it is plugged in Execute dmesg to get an idea of the most recent kernel messages Using the USB cable connect the scope hardware to a USB port Execute dmesg again and y
25. 2 05 2009 11 37 AM E 13KB CSV File 22 05 2009 11 37 AM E May 22 2009 11 37 30 csv 13KB CSV File 22 05 2009 11 37 AM May 22 2009 11 37 37 csy 13KB CSV File 22 05 2009 11 37 AM May 22 2009 11 37 44 csv 13KB CSV File 22 05 2009 11 37 AM E May 22 2009 11 37 51 csv 13KB CSV File 22 05 2009 11 37 AM Z May 22 2009 11 37 57 csv 13KB CSV File 22 05 2009 11 37 AM E May 22 2009 11 38 04 csv 13KB CSV File 22 05 2009 11 38 AM E May 22 2009 11 38 11 csv 13KB CS File 22 05 2009 11 38 AM E May 22 2009 11 38 18 csv 13KB CSV File 22 05 2009 11 38 AM E May 22 2009 11 38 25 csv 13KB CSV File 22 05 2009 11 38 AM Figure 25 Directory with Files usb serial device plugged in the number might be some other digit than zero This port has read write permissions for root and for the dialout group It does not have read write permis sions for a lowly user so the instrument will not connect in this state You can change the permissions on dev ttyUSBO but the port is transient and disappears when you shut down or disconnect So you would need to do that every time you start the instrument To make this permanent add your name to the dialout group I tried to do it using the edubuntu system administration tool but for some reason the dialout group did not appear To do this the old fashioned command line way use the command groups to see which groups you belong to Probably dialout does not appear We will edit the groups file to add you
26. Installation Overview The installation should work correctly under modern versions of Windows Linux and Macintosh operating sys tems Installation only needs to be done once thereafter the program can be started by double clicking on an icon 16 1 Windows Download the Windows setup executable from our website www syscompdesign com downloads Run 1t Everything including driver install is automatic 16 2 Linux Download the Linux zip archive from our website unzip it into a folder of your choice where you have permis sions Run either the Instal1 Linux 32 bit shor Install Linux 64 bit sh 16 3 Macintosh Download the DMG image from our website www syscompdesign com downloads Open it First drag the CGR MINI icon into the Applications shortcut in the DMG Then run the driver installer in the DMG As of August 2012 Apple has added a Gat eKeeper function to OSX Mountain Lion and subsequent oper ating systems Gatekeeper prevents installing the Syscomp software and generates a Defective Software message You ll need to disable Gatekeeper while doing the download and install A Google search for OSX disable gatekeeper will show the necessary instructions Gatekeeper should be re enabled once the installation is completed and it is verified that the software is operational 16 4 First Time Operation These instructions apply to all operating systems Windows Linux and Mac 1 Using the supplied USB cable or similar one o
27. Mfr 1 Product 2 SerialNumber 3 usb 1 2 Product Digital Oscilloscope DSO 101 usb 1 2 Manufacturer Syscomp usb 1 2 SerialNumber DSQ307Z0 usb 1 2 configuration 1 chosen from 1 choice sb serial usb serial c USB Serial support registered for FTDI USB 1 2 31 0 sb serial ftdi_sio c FTDI USB Serial Device converter now attached to ttyUSBO FTDI USB Serial Device converter detected Detected FT245BM drivers u registered new interface driver ftdi_sio sb serial ftdi_sio c v1 4 3 USB FTDI Serial Converters Driver 21f the file does not exist please let us know the name of the Linux distribution and we ll look for another solution 50 This indicates that the oscilloscope was detected and it has been assigned to the USB Serial port tt yUSBO You now go to the director dev and examine the tt yUSBO entry phiscock panther dev gt ls 1 ttyUSBO crw rw 1 root uucp 188 0 2008 04 20 12 57 ttyUSBO The uucp group have read write permission to this device so the permanent solution is to add uucp as one of your groups In Suse 10 3 this is done from Computer gt Control Center gt Open Administrator Settings You ll need to enter the root password Then goto Security and Users gt User Management gt User and Group Administration Select the user that s you and click on Edit This brings up the Existing Local User page Click on Details Under Groups check off uucp Log out and log back in or re
28. S or by using the default package manager this will work for 32 and 64 bit systems Also the Bwidget package should also be listed as a dependency the package name is bwidget all lower case apt get install bwidget will install it on the system 18 3 9 Device Properties using usbview In general it s not necessary to know anything about the USB properties of the hardware in order to use it However if you do want to inspect those properties usbview is useful It is likely that you will have to install usbview from your Linux distribution disks Once usbview is installed figure 26 you can use it to determine whether a USB device is recognized by the operating system USB As a USB device is plugged and unplugged an entry appears and disappears in the usbview window Clicking on an entry opens up a list of USB properties of the device Notice that usbview does not indicate the serial port dev ttyUSB2 or whatever that the operating system has assigned to this device You must use dmesg for that purpose 54 USB Viewer EHCI Host Controller UHC Host Controller Waveform Generator WGM 10 E UHCI Host Controller USB lt gt Serial Cable UHCI Host Controller UHCI Host Controller Waveform Generator WGM 101 Manufacturer Syscomp Serial Number WGO3BR3J Speed 12Mb s full USB Version 2 00 Device Class DD gt ifc Device Subclass 00 Device Protocol 00 USB PS 2 Op
29. Setting Default Port Permissions to User Mode Suse 9 2 This change will ensure that the serial usb ports are always created with user mode access The default permissions for user devices are contained the file etc udev permissions d 50 udev permissions We have to modify the entry for the tt yUSBx ports so that the default is user mode 1 Change to the directory etc udev permissions d andcheck that the file 50 udev permissions ex 1sts 2 If the file exists enter root mode and copy the existing file so you have a copy of the original cp 50 udev permissions 50 udev permissions orig 3 Now open the file 50 udev permissions with your favourite editor Find the entry that says ttyUSBx root uucp 660 Change that to read ttyUSBx root uucp 666 Save the file Now every time a ttyUSBx port is created you should be able to access that port without problems 18 3 3 Setting Default Port Permissions to User Mode Suse 10 3 Suse in their wisdom have changed the method detecting USB devices Now USB devices do not exist in dev until they are plugged in Plug in the DSO 101 oscilloscope and execute dmesg You should see something like the following at the end of the message drivers u Serial Device ftdi_sio drivers u usb 1 2 usbcor usb 1 2 new full speed USB device using uhci_hcd and address 2 usb 1 2 new device found idVendor 0403 idProduct 6001 usb 1 2 new device strings
30. Syscomp Computer Controlled Instruments CircuitGear Mini Manual Syscomp Electronic Design Limited http www syscompdesign com Revision 1 0 August 21 2013 Triggered Options Channel B Square Triangle Sawtooth Stored Custom Load Custom eae AS gt Save Custom Sweep Mode Logarithmic Options C Linear Digital inputs Y Digital Outputs 5 Frequency aesaceaaa A a Revision History Version Date Notes 1 00 September 2012 First revision Contents 1 Overview 1 1 Oscilloscopes 2 a A a e od ERM EHO 12 Waveform Generator 32 trepa bw ew Bae Eee ee ee eee 1 3 Digital mput Output cenit SOR ae ees RS ee EO EO a Bd aS 1 4 Vector Network Analyser Bode Plotter 2 2 2 ee 1 5 Spectrum Analysef ssa sica a Se aw Ree aS a dd ae bee es 1 6 General us Sk aoe ae Oe ee ee A Oe wae ew ele See AAA 1 7 Software Updates and Help 5 4 5 ea Ooh ek OO Se Ee e de dE 2 Applications 3 Features and Specifications 4 Installation and Operation 5 Oscilloscope 5 1 AMPpltUdS ies pe eke eae Pee bebe Aa a 5 2 Oscilloscope Mode Timebase 0 e a e a a 5 3 Oscilloscope Mode Display 000 ee ts nirtssa 54 Oscilloscope Mode Triggering sporire ee ee 259 Measurements Screen woos ee ee ee eee eee eee 516 XY Mode 2 24 cee ee 6A Wa be HS Gok eh eh Gwe ak ie eee Ge eh a de E Sr 5 7 Screen Capture serengo pme gah
31. Tcl Tk Tools Mark Harrison O Reilly 1997 Information on a number of extensions to Tcl Tk 57 Effective Tcl Tk Programming Mark Harrison Michael McLennan Addison Wesley 1998 Techniques of design for Tcl Tk programs Tcl Tk for Programmers Adrian Zimmer IEEE Computer Society 1998 An textbook on Tcl Tk with an academic tone and exercises Tcl Tk for Dummies Tim Webster IDG Books 1997 A useful introduction to Tcl Tk Tcl Tk for Real Programmers Clif Flynt Academic Press 1999 Medium to high level material on Tcl Tk 58
32. ange the appearance of your desktop such as the background screen s Folder Options Customize the display of files and folders change file associations and mak fronts Add change and manage fonts on your computer T Game Controllers Add remove and configure game controller hardware such as joysticks an intel oma Driver for Mobile Control the graphics hardware features of your system WP internet Options Configure your Internet display and connection settings Seva Java TM Control Panel Sakeyboard Customize your keyboard settings such as the cursor blink rate and the ch T Mouse Customize your mouse settings such as the button configuration double cl WE Network Connections Connects to other computers networks and the Internet F Network Setup Wizard Launch the Network Setup Wizard s Phone and Modem Options Configure your telephone dialing rules and modem settings ED Portable Media Devices View the portable media devices connected to your computer By Power Options Configure energy saving settings for your computer printers and Faxes Shows installed printers and fax printers and helps you add new ones QA QuickTime Configures QuickTime software and hardware components 4 Regional and Language Options Customize settings for the display of languages numbers times and dates Scanners and Cameras Add remove and configure scanners and cameras scheduled Tasks Schedule computer tasks to run automatically Secur
33. aningful As well the frequency and period measurement can be fooled if the waveform includes noise that causes multiple spurious zero crossings The RMS measurement requires that the time cursors be visible and set to the beginning and end of one cycle This is required to define the limits of integration in the RMS calculation 10 Frequency da oiod 099 47 us 5 Average PF at Zn A EJ Maxirrum 2 03 ca me rt Minim im 2144 E2 mu AN 5 n_n 7 Peak Feedk 17 TT BH ems Taro TA md GMs Figure 5 Measurement s Screen For multiple measurements on a reasonably clean waveform the Auto Measurements can be a real time saver However it is best to verify that the measurement is reliable before relying on it extensively 5 6 XY Mode Fie View Tools Hardware Help onnected Syscomp Digital Storage Oscilloscope Vertical Controls gt T Trigger Controls Channel A Disable peace Ce a y mW Auto a i i Single Shot Reset Ma Trigger Slope f W Y La Trigger Source pa Manual Tri Disable ow ei 1 poate Timebase Controls q AAA A eek ees iw l 1 Lad Tie Figure 6 XY Display Mode The usual oscilloscope display shows a plot of the two signal amplitudes voltage on Channel A and Channel B vs time It is also possible to plot the two voltages against each other Channel A as the X ax
34. aveform Generator aveform Generator 9 1 Triargk Savtocth Custom Sweep Made Logerithmiz O Linear Figure 8 Generator Controls could set the frequency range to 3050Hz maximum and 2950Hz minimum Then the adjustment range of the gen erator is 100Hz giving effective fine grain control of frequency 6 3 Sweep Mode The control characteristic of the frequency slider can be set to Logarithmic or Linear The Logarithmic control increases the frequency in an exponential fashion as it is increased which is the most convenient characteristic is most situations In Logarithmic Mode the physical mid point of the scale corresponds to about 700Hz In Linear Mode the control characteristic is linear and the mid point of the control is 1 5MHz In effect this assigns most of the physical movement to high frequencies 6 4 Manual and Automatic Sweep The CircuitGear GUI provides frequency control of the generator with a manual frequency control Automatic sweep is provided with a separate feature the VNA Vector Network Analyser aka Bode Plotter software which operates the generator to make a sweep and the oscilloscope to plot the response of some device or network See section 9 on page 21 14 6 5 Waveform Amplitude The waveform can be adjusted between 0 and 2 5 volts peak Combinations of amplitude and offset that exceed 2 5 volts will cause the waveform to clip You can also left click
35. aximum Waveform Amplitude 7 O 10 20 30 40 50 60 70 80 90100 START STAP Curent Frequency 360 8 kHz Channel A Preamp 25V Max Channel B Preamp 25V Max Waveform Amplitude 2 50 Analyzer Status Ide Oscilloscope Display VWWWWWWAM Figure 12 Vector Network Analyser As part of their AC Circuits lab electrical engineering students are required to plot these response curves by hand This is a very tedious process Each point in the plot requires setting the generator frequency reading the input signal amplitude reading the output signal amplitude reading the output signal phase and plotting the result The CGR 101 vector network analyser does this automatically over a range of 1Hz to 1MHz or some part thereof This makes it practical to explore the effect of changing component values For example if the resistor or capacitor value in an RC lowpass filter is changed one can immediately determine the effect on frequency and phase response The CGR 101 has two principal modes as an oscilloscope and signal generator with digital input output and as a network analyser To change between them select Hardware gt Network Analyser Mode or Hardware gt Circuit Gear Mode
36. ay range Select Linear Sweep to precisely set the display frequency span to the previously entered Start and End frequencies e Select the maximum amplitude range e Press Start and the analysis will proceed If the sweep range is substantially outside the passband of the filter the VNA may complain about insufficient signal In that case change the sweep range to start and end on the skirts of the filter 9 3 VNA Theory More information on the theory of the vector network analyser is in the Syscomp Application Note A Software Based Network Analyser at http www syscompdesign com na theory pdf 10 Rear Panel Connector The rear panel connector provides access to the following signals Digital outputs O through 7 Digital inputs O through 7 External trigger output PWM Pulse Width Modulated output External trigger input e Ground The pinout is shown on the case label of the instrument and in figure 13 below These functions are described in section 7 above Ext Trig In PWM Out 7 6 5 Digital Outputs 19 17 15 13 11 20 18 16 14 12 7 6 5 Digital Inputs Key GND Trigger Out CircuitGear Rear Panel Connector View toward rear panel Figure 13 CGM Mini Rear Panel Connector Pinout 23 10 1 Rear Panel Connector Mating Plug One suitable rear panel connector mating plug is as follows MODE part 35 0202 0 20 position 2 row 0 1 2 54mm contact spacing Mates with 20 way 0 050 spacing fla
37. chanical system for resonances can be done by driving the system with a wide band excitation signal an impulse hammer blow or random noise from a shaker Microphones or accelerometers convert the mechanical vibration of the system to an electrical signal The spectrum analysis of this signal indicates the mechanical resonances in the structure e The extraction of signals from noise may require some knowledge of the spectrum of the signal and the noise e It is useful to see the spectrum diagram for modulation and other signal manipulations Further information on spectrum analysis is in the paper Introduction to Digital Spectrum Analysis which is on the Syscomp web site 20 9 Vector Network Analyser An electrical network such as a lowpass filter is charac terized by its amplitude and phase response The ampli oo A E tude response is a plot against frequency of the gain of I the network the ratio of output signal amplitude to in Generator Scope put signal amplitude The phase response is a plot of the Output phase of the network the difference between the output phase and input phase The test signal is a sine wave that is swept over a range of frequencies taking care not to overload the network Channel A Input Test Network Figure 11 Network Analyser Wiring j Syscomp CircuitGear 101x Fie View Tool Hardware Help Start Frequency Lo j EE J End Frequency WOU Frequency Step 111 a A M
38. cted some activity should be visible on the scope trace the red LED on the scope hardware should flash The unit is operational 17 3 Linux Installation 1 2 Point your browser at the Syscomp website www syscompdesign com Navigate to the Downloads section Download the file for the Linux operating system Unzip that file Move into the directory created by the unzip operation Change to the Source subdirectory Copy all files and folders from the Source directory to a suitable directory on your machine for example home yourname Syscomp CGM101 42 3 Copy the appropriate binary file from the Source bin directory into the folder you selected or execute the appropriate shell script in the Source directory For example sh Install Linux 32 bit sh or cp home yourname Syscomp CGM101 bin linux linux_ix86 CGM101 lLinux x86 home yourname Syscomp CGM101 The above command should be executed on one line 4 Execute the binary executable to start the software For example use these two commands cd home yourname Syscomp CGM101 CGM101 linux x86 17 3 1 Hardware Installation 1 Plug the hardware device into an available USB port 2 Run the program dmesg to show which serial port the instrument has been attached For example dev ttyUSBO 3 Start the binary executable the GUI Graphical User Interface as described above 4 On the GUI use the Hardware gt Port Settings menu in the instrument software
39. cuts in the following Start Menu folder To continue click Next If you would like to select a different folder click Browse Browse mp Cicuiear 1 13 mes oe ee A b Select Destination TE 5 xi Ready to Install Setup ie now ready to begin nstaling Syscomp CircuitGear on your computer lt Back Cre gt Cancel c Select Start Menu Folder tup Syscomp CircultGear E palsies Installing Please wait while Setup installs Syscomp CircuitGiear on your computer Select the additional tasks you would like Setup to perform while instaling Syscomp CircuitGeer then cick Next TF Create a Quick Launch icon Click Install to continue with the installation or click Back if you want to review or change any settings Destination location C Program Files Syscomp CGR101 1 13 Start Menu folder Syscomp CircutGear 1 13 Extracting fles C Program Files Syscomp CGR101 1 13 Source Images 200us gi lt Back Newt gt Cancel d Additional Tasks Syscomp USB Device Driver Installer Welcome to the Syscomp USB Device Driver Installer This wizard wil walk you through pre instaling drivers on your computer To continue click Newt lt Back lt Back E instal e Ready to Install Syscomp USB Device Driver Installer Installing the s for your Syscomp device is A Please wait while the drivers install This may ta
40. d the other to a header pin on a PC board Both types of leads are available from Creatron in Toronto http www creatroninc com 11 Safe Measurement Technique These notes are included for the benefit of those who are new to using an oscilloscope The information is not unique to this oscilloscope but applies to most oscilloscope measurement instruments 24 Rather than simply state rules and prohibitions we explain why certain procedures are dangerous and why some techniques should be avoided This information is provided for guidance in using the oscilloscope and is not intended to replace proper training in working around high voltage circuits In general this oscilloscope may be used safely to observe signals in low voltage circuits where the power supply is floating from the AC line 11 1 Floating Power Supply er e an Power Line Ground Power Supply Computer CAS E Input OS Input a PO Red p 5 ine 1 LA l Ground i 2 I e a Black f AS nN Ground e Green E eo en A ce ey a eee gt Figure 14 Floating Power Supply In this context floating power supply is one in which neither terminal is connected to the power line ground Consider the circuit shown in figure 14 Like many lab power supplies the power supply has three terminals positive negative and ground The ground terminal is connected to the third prong on the line cord which connects to the power line ground w
41. detect the port If the port does not autodetect then select some port manually Select a high ish number something above 15 for example The lower numbers tend to get used first It s not unusual for autodetect to fail and manual to work Once the port is selected you should never have to do that again 47 5 At that point the device should connect Now if you need other devices you can enable them one by one to find where is the conflict If problems continue please take a screen shot of the expanded Ports COM and LPT and send it to us and we will assist 18 3 Linux These troubleshooting notes are specific to Suse Linux 9 2 but should apply in general They also assume a working knowledge of Linux and its variants Overview If the software does not operate correctly here are some things to check They are subsequently explained in detail The operating system is too old and does not contain the necessary drivers for the usb serial ports The operating system for some reason is not recognizing the usb device and assigning it to a usb serial port This can occur if the usb device has root ownership and permissions The permissions must be changed to allow a user mode program to access the usb port The operating system is assigning the hardware to some usb serial port but the Tcl Tk program is not automatically selecting that particular port You ll need to select the usb serial port manually using the controls in
42. dure is briefly described in section 16 page 38 and in more detail in section 17 on page 39 5 Oscilloscope The oscilloscope Graphical User Interface GUI is shown in figure 2 PE Syscump Cirit Gear Mini Fie View Tools Hardwarz Help Oscilloscone Manua Triage Triggo Mode Asbo E Sing e Shthteset intirns Figure 2 Oscilloscope GUI Many of the scope controls are similar in function to those of the classic analog oscilloscope Other controls are unique to the CGM 101 They provide functions such as cursor readouts that are only possible in a digital oscilloscope The scope controls divide into various groups amplitude timebase display and triggering 5 1 Amplitude There are two input channels A and B each with identical controls e Scale Sets the vertical scale factor of the display between 20mV per division and 5 volts per division in the traditional oscilloscope 1 2 5 sequence The amplitude may be read off the display by measuring the number of divisions and multiplying by the scale factor Alternatively the display amplitude cursors may be used see display below Changes to the scale control adjust the sensitivity of the front end of the oscilloscope adjust the preamp gain and change the software scale factor e Option This button opens a sub menu with the following controls Coupling DC and AC This switch controls the input coupling of the oscill
43. e In combination these controls form the basis for digital controls and displays for basic digital exercises or more advanced control systems 1 4 Vector Network Analyser Bode Plotter For automatic sweep a Vector Network Analyser VNA aka Bode Plotter program is available The VNA software operates the oscilloscope and generator sections in concert to sweep a network over a specified range and plot the amplitude and phase of the response 1 5 Spectrum Analyser A frequency spectrum of the input signal can be shown at the same time as the time domain waveform display on the oscilloscope screen The spectrum display is generated by the Fast Fourier Transform algorithm so that it responds instantaneously to changes in the input waveform This is ideal for demonstrating the relationship of signals in the time and frequency domains 1 6 General The hardware is in a pocket sized package that can easily be carried in a student backpack or with a laptop computer Power and control signals are provided to the hardware via a single serial emulated USB connection with the host PC An external power module wall wart is not required The PC host displays a graphical user interface for the oscilloscope with frequency readouts sliders clickable buttons and various other controls Each instrument appears in its own window unused instruments can be minimized The screen of the oscilloscope is resizeable The hardware is entirely controlled by sof
44. e AAA 5 8 ANAS 22d e ds y a dee 6 Waveform Generator 6 1 Setting Frequency 4 a eru daite Rakin wok BOR Ba ee A ea Re 6 2 Setting Sweep Limits ee eee 6 3 Sweep Models s s s bse BG ake Se aa Oh e a ee hho bd ah heb aes 6 4 Manual and Automatic Sweep 2 2 0 00 000 ee 6 5 Waveform AmplitUde p s cs e m oepa a RR BRE A 6 6 WavelormOltsetl ooo Sa She OS Pe eRe eee ee ee eee Ee Pa eee ee 6 7 Waveform Selection sa ios neo 4s bbe es ws ee PEE SA EERE EAH Sed ee 6 8 Wavelorm Format e s ol x eee ow Ae Be ape ee a we ee 7 Digital Input Output Section 7 1 8 Bit Digital Output c co t bee Rw a A a bnew des 7 2 S Bit Digital Input lt a a a e a Ta A oe Be A eB GL ee ae 13 PWM Pulse Width Modulated Waveform 2 2 0 000 2 eee ee es kA Extemal Triggers s a acc he as HR a A a bee Ble OR oe oe es Po ae 8 Spectrum Analyser 8 1 8 2 8 3 8 4 8 5 Interpreting the Spectrum Analyser Display o o e e Frequency Scale Bin Spacing o so secre amea uo e eui a e e a a y a a a Spectrum Display Cursor Contool s se essre erer ena ee Spectrum Weighting Functions sasaaa aae ee APplCations s sa a wet es a deme at Se A a A ode de rico alle de ee a a 14 14 14 14 14 15 15 15 15 16 16 16 16 16 10 11 12 13 14 15 16 17 18 Vector Network Analyser 9 1 Phase Display lt 522 508 4 2745 64 Soe a A eee ee wa ee 9 2 Linear and Narrow Band Sweep osos ake e
45. e CGR 101 is 500 points This is padded to 512 points by appending zeros to the waveform record As a result there are 256 frequency bins when using the main oscilloscope display The centre frequency of each of these bins may not coincide exactly with the frequency components present If that is the case then the displayed amplitude will be incorrect and should only be regarded as an approx imation of the true situation e As the readout cursor is dragged higher in frequency it jumps from bin to bin reading out the centre frequency of each bin A given frequency component may not be centred in its bin so the frequency readout 6The FFT routine requires that the number of points be a power of 2 18 will be only approximate For example in figure 10 the square wave frequency generated by a Syscomp WGM 101 waveform generator is at a frequency 1kHz to within a fraction of a Hz The 9th harmonic is at 9kHz The spectrum display readout puts the 9th harmonic at 9 0234 Hz which is approximately correct 8 2 Frequency Scale Bin Spacing It is sometimes useful to be able to determine the resolution of the frequency axis Each frequency bin has a width Af 1 T Hz where T is the length of the data record in seconds If there are N points in the data record then N 2 points are displayed as positive frequency The other N 2 points are redundant Example Determine the frequency resolution bin spacing for the case of the display of figure
46. e analog control signal In this exercise students design the PWM filter and then measure the ripple using the CircuitGear oscilloscope They can also operate the PWM signal at various frequencies to illustrate the effect of frequency on ripple 3 Features and Specifications Oscilloscope Channels Sampling Frequencies Vertical Resolution Vertical Bandwidth Vertical Input Range Vertical Gain Settings Vertical Coupling Vertical Offset Vertical Scale Horizontal Time Settings Timebase Mode Horizontal Time Settings Strip Chart Mode Horizontal Scale Input Impedance Triggering Trigger View Trigger Controls External Trigger Out External Trigger In Memory Depth Software Waveform Generator Frequency Range The features and performance specifications are as follows 2 independent channels sampled simultaneously 2 MSamples second maximum 12 bits per channel 1 4096 200 kHz 250mV to 25V full scale 9 settings 10mV div to 5V div in 1 2 5 sequence AC or DC coupling Full screen 20V max 10 major divisions 17 settings in 1 2 5 sequence 100mSec div to 500nSec div 7 settings in 1 2 5 sequence 200 mSec div to 20 seconds Div 10 major divisions 1M Ohm parallel 27pF Digital comparison with input signal Pre and Post trigger simultaneously viewable Source A B Manual level and slope select Rear panel source channel A logic level Rear panel logic level signal 1K Samples each channel Cursor Readouts Spectrum
47. e the screen image of the oscilloscope the generator or the digital IO section to a screen image Usually one is interested in capturing the oscilloscope showing the waveforms This type of screen capture is useful because it also captures the control settings which is important for complete documentation 12 The various computer operating systems use different methods to capture to capture a window or full screen Windows XP To capture the entire desktop multiple windows press the Print Screen keyboard key To capture a single window such as the oscilloscope position the mouse cursor somewhere inside that win dow and press the Alt and Print Screen keys simultaneously Both these actions copy the screen image to a cut copy paste buffer To view the screenshot and save it to a file open Programs gt Accessories gt Paint Inside paint choose the menu item Edit gt Paste and the image will appear in the Paint workspace Now you can save it to the directory of your choice in the file format of your choice using the File gt Save As menu item The precise instructions for other Windows operating systems are similar to XP Mac Sue Chastain describes several methods of screen capture on the Mac http graphicssoft about com od screencapturemac ht macscreenshot htm Here s her method of capturing a specific window such as the oscilloscope window To capture a specific application window press Command Shift 4 the
48. ed USB port 3 Start TeraTerm The New Connection window appears TCP IP is selected by default Change the selection to Serial 4 On that same window select Port In this case it shows COM3 and COM5 USB Serial Port For example if we know the CGM 101 is connected to COMS select COMS Click on OK Window closes 5 Select the menuitem Setup gt Serial Port The port has been selected no need to change that Set the Baud Rate to 230400 Set Data Bits to 8 Set Stop Bits to 1 Set Parity to None Set Flow Control to Hardware Click on OK Window closes 6 Select the menu item Setup gt Terminal Change the New line Receive to CR LF Change the New line Transmit to CR LF Click on OK Window closes 7 In the main terminal window type the letter i followed by the Return key You should see a message something like Syscomp Advanced Waveform Generator V1 0 1 0 If so you are now connected and can issue commands to the generator Notice that all commands are terminated by the Return key 14 3 Linux For manual operation under the Linux operating system you will need to communicate with the hardware us ing a terminal emulator program There are two terminal emulators in common use under Linux seyon and minicom These may not be installed as part of your linux distribution To check whether the program is installed use the which command phiscock panther gt which seyon usr X11R6 bin seyon Seyon mus
49. ed ea Re ee aS hea eRe 9 3 VINA Theory 35 465 a Yee nde ee ee A Wee a le eae aed a at Rear Panel Connector 10 1 Rear Panel Connector Mating Plug 2 2 o e 0 000 000 00000 Safe Measurement Technique 11 1 Floating Power Supply dros ii ee Ae A RE a a ES 11 2 Grounded Power Supply 0 00 ee ee 11 3 Battery and AC Adaptor Power Supplies ee ee 11 4 Russian Roulette and AC Line Voltage o e o 1S Remoying the Ground ar ces dy oe as pt e e A ee OPS Sy 11 6 Observation of AC Line Voltages s sy 22200 Fe eee SER EW A eee eee EES Adjustments 12 1 Input Compensation Capacitors s s ss ss ras ssar ee aa ta s e T a Instrument Commands 13 1 Using the Debug Console c i425 2 58 5 reido e685 aa e A a eee ES 13 2 CircuitGear Mini ASCII Command S tt 000 000 0000 Manual Operation t41 Windows ie seca 6 483845 AA AAA RA Ke 14 2 TeraTerm An Alternative to Hyperterminal e e MS LIMON ae aa E A e A AAA A at Modifying and Running the Source Code 15 1 Preparation for Modifying the Software o o e 15 2 Modifying the Software 2 lt lt 2 e ss Installation Overview 16 1 Windows 24 p28 hac ee ada a a Re ESS Ee 16 2 LINUX oe ais ote lee aa A we aes Ew a eR OR ee Rk wl Bea A 16 3 Macintosh sose eios 4 on bap bea bee eas A GS ae Pe ea ee ee Ge A 164 First Time Operation g seiis a 8S OSes ESS dd BS oe Installation Details 17
50. ed file Execute that file by double clicking on it The CGM 101 icon appears on the desktop Open it Open setup htm ZA nD wm Click on Click here for the DMG installer 8 Open CircuitGear dmg 9 A screen appears on the desktop showing the Applications folder and the Syscomp CircuitGear unit Drag and drop the Syscomp image onto the Applications folder A progress bar appears and completes Shttp www tcl tk software tcltk platforms html 41 10 11 12 13 Go to the Applications folder Finder gt Macintosh HD gt Applications Find the entry for the Syscomp CircuitGear Double click on it The CGM 101 GUI should appear It will probably show Not Connected in red A dialog box will pop up saying Examine hardware settings Click on Yes Examine the hardware settings Select the entry that says cu usbserial xxxx where xxxx is some serial number The gui indicator should turn green and show Connected If the GUI does not connect exit from the gui Unplug the CGM hardware and plug it in again Restart the GUI and this time the hardware should connect properly The program should indicate Connected some activity should be visible on the scope trace the red LED on the scope hardware should flash The unit is operational 17 2 3 Installing Driver In order to connect the USB Serial driver must be installed on the Mac On some machines this is in place without further intervention However i
51. erface appear 15 2 Modifying the Software The host software for the scope and other Syscomp instruments in this series is released in plain text format under the GPL Gnu Public Lincense Consequently it is legal to modify the program in whatever way you may find useful We also encourage you to share your work with others The program itself is in text form The code does not need to be compliled or linked it is executed directly from the text form by the wish interpreter Although the scope program is fairly complicated it is possible to create a powerful Tcl Tk program with a sophisticated user interface with only a few lines of Tcl Tk code To set up for development ensure that the wish interpreter is installed on your computer Under Linux it is probably already there Under Windows you need to download and install a file from the ActiveState website 37 http www activestate com Products languages plex tn 1 Download the appropriate exe file for your operating system Run the program to install Tcl Tk Make a copy of the original code of course and put it in a safe place Then using a text editor read and modify the existing code When you want to test the code run the wish interpreter Execute the source command with the name of your file and the program will execute Repeat this cycle until you have the desired result We d like to hear about your work Check out our web page for the latest contact information 16
52. es http www syscompdesign com Latest information on Syscomp instruments and supporting software Many useful application notes and project descriptions http www tcl tk Home of the Tcl Developer Xchange Pointers to information and software downloads http www activestate com ActiveState is a commercial firm that sells various programming tools provides a home for the Tcl Tk language Free versions of Tcl Tk are available for download from their site 19 3 Paper Scripting Higher Level Programming for the 21st Century John K Ousterhout IEEE Computer magazine March 1998 Currently at http home pacbell net ouster scripting html Also at http www tcl tk doc scripting htm The definitive paper on Tcl Tk and scripting languages in general Ousterhoot shows a Table of Applications which have been coded in Tcl Tk and in the C language and the relative effort and time required for each imple mentation 19 4 Textbooks Practical Programming in Tel and Tk 4th Edition Brent B Welch amp Ken Jones with Jeffery Hobbs Prentice Hall PTR 2003 The definitive reference for Tcl and Tk Includes CDROM with Tcl and examples Tcl and the Tk Toolkit John K Ousterhout Addison Wesley 1994 Now somewhat dated but a still useful introduction to Tcl Tk by the inventor of the language Graphical Applications with Tcl amp Tk 2nd Edition Eric Foster Johnson M amp T Books 1997 Very accessible introductory textbook
53. f the tcl program can be used As well the KDE and Gnome graphical user interfaces be used to set up an icon on the desktop Then clicking on that icon will start the program 10K indly supplied to us by John Foster 51 18 3 6 Ubuntu Linux Install This sectiondescribes how to install the DSO 101 oscilloscope software on a Ubuntu Linux system This proce dure was tested on an Edubuntu system Hardy Heron April 2008 Similar instructions apply to installation of the WGM 101 Waveform Generator CGM 101 CircuitGear and CGM 101 CircuitGear Mini with the corre sponding file names These instructions assume some familiarity with Linux Specifically you must know how to use an editor to modify files You should know how permissions work and how to use the chmod command to change them You should have some familiarity with the directory structure and the location of your home directory vs system directories such as etc and dev You must know how the 1s command works Download and Unpack the Software a eelab File Browser File Edit View Gn Hookmarks Help e 0 ur a Back Up Reload Horre Computer Search lt peter eelab a Places v x O peter Lj Desctop DSOICIVISIO WEMIO Iv p lin zip file System Floppy Krive a Network Servers Tras Documents TE Music Pictures videos Figure 24 Checking that the File has Downloaded The software is available for download from the Syscomp website www
54. f you followed the previous steps and the hardware still will not connect you may have to download and install the driver 1 Point your browser at this website http www ftdichip com Drivers VCP htm This is the website for the FTDI Virtual Com Port VCP driver that is needed Find and click on the driver that corresponds to your operating system Mac OSX and processor type x86 or x64 At the time of writing the same driver 2 2 17 applies to both types of processors Click on that driver number A window will open allowing you to download the driver You should now have a DMG version of the driver on your desktop Double click on that file to run it This will install the driver When that completes restart the Syscomp GUI software as you did before Go to the Applications folder Finder gt Macintosh HD gt Applications Find the entry for the Syscomp CircuitGear Double click on it The CGM 101 GUI should appear It will probably show Not Connected in red A dialog box will pop up saying Examine hardware settings Click on Yes Examine the hardware settings Select the entry that says cu usbserial xxxx where xxxx is some serial number The gui indicator should turn green and show Connected If the GUI does not connect exit from the GUI Unplug the CGM hardware and plug it in again Restart the GUI and this time the hardware should connect properly The program should indicate Conne
55. f your own choosing plug the oscilloscope into a computer USB port If you have more than one USB port you can chose any port 2 The green LED on the hardware unit should illuminate Under Windows the computer will make its USB boing noise 3 There should be a Syscomp icon on the desktop The exact name will vary but it should be something like Syscomp CircuitGear Start the oscilloscope program by double clicking on this icon 4 Ascreen Unable to Connect to Device Examine Connection Settings appears Click on Yes 5 The Port Settings control panel appears Click on Autodetect 6 The program scans through the available COM ports through 99 38 10 If it finds an available port a notification screen will pop up saying something like C6EM 101 found on COM6 If it does not find an available COM port try clicking on Autodetect again If this also fails you ll need to set the COM port manually section below Assuming that the system finds an available COM port click on OK A Port Settings Listing window shows a list of the unavailable COM ports and the one that was found Click on Back The Port Settings control panel shows which port has been selected Click on Save and Exit This causes a small text file scopeport cfg to be written to the directory where the scope program was launched This file contains the connection port number At this point the Connected indicator at the top of the GUI sc
56. h is extremely complicated We refer to this as a USB serial interface The USB serial has major advantages over the traditional serial port First the data transfer rate is much faster especially using the USB2 0 standard Furthermore power is transmitted from the host to the hardware over the USB cable so that an AC adaptor is not needed Third the USB system handles enumeration automati cally so that multiple devices are accessed correctly without manual configuration 43 e Under Windows the FTDI USB serial drivers are automatically loaded by the Install program so the user should not normally be required to intervene Thereafter the operating system always associates that hardware with that serial port even if it is plugged into a different USB port Under Linux the FTDI driver is included in the Linux kernel since 2 4 so it does not need to be installed under Linux The assignment of the USB Serial port depends on the order of connection of devices If you are just using one USB Serial device then the same port will be assigned each time If you are using multiple USB Serial devices which in general will work correctly then you will need to plug in each device one at a time and run dmesg to determine the port assignment In Linux the default permission of the dev tt yUSBx ports is set for root access only so the permissions must be changed as described under 18 3 The x in dev ttyUSBx represents a number for a ttyUSB
57. he output drive current should be limited to a few milliamperes of current 7 4 External Trigger When the Trigger Mode control on the GUI is set to External a positive going transition on this pin rear panel pin causes the scope to trigger To test external trigger 1 Set the trigger mode to auto 16 2 Connect the output of the generator to channel A of the scope and adjust the generator amplitude so the scope shows a sine wave 3 On the rear panel use a jumper cable to connect the Ext Trig pin to the Digital output 0 pin 4 Under Trigger Mode select External 5 From the GUI use the mouse to click on Digital Output 0 6 On the OV to 5V transition on digital output 0 the scope should briefly display triggered and a new sample of the waveform should display On the 5V to OV transition triggering will not occur Edge polarity is not selectable on external triggering the trigger edge is always positive going The trigger input is protected against overvoltages but we do not recommend relying on that We recommend keeping the trigger signal between 0 and 5volts 8 Spectrum Analyser A complex waveform may be treated as being composed of a number of sinusoid waveforms These sinusoids are of various phases frequencies and amplitudes The description of the magnitude phase and frequency of these various waves is known as the spectrum of the signal by analogy with the spectrum of light Spectrum Analysis
58. he probe near the handle Adjust this screw for best square wave response 28 13 Instrument Commands These commands are low level instructions to the scope hardware The commands and where relevant messages back from the hardware are ASCII strings so that they can be generated easily by software or a human operator There are two situations where the interface commands may be useful e The scope hardware may be operated directly from a terminal emulator program such as Hyperterminal under Windows Minicom or Seyon under Linux e Knowing the commands allows one to create a scope control program with different functionality For example a program could be created to read the oscilloscope and plot the results on a strip chart type of display Should undertake such a project the Tcl source code for the Oscilloscope GUI which is included in the install files will be a useful source of ideas in controlling the scope There is no requirement that the controlling program be written in the Tcl language Any program that can issue ASCII strings to a serial port will be capable of controlling the scople hardware eg Mat lab Visual Basic 13 1 Using the Debug Console When you send a command to the scope it does not echo any confirmation back to the host terminal This is because you are doing with the terminal exactly what is done with a control program and responses from the scope would slow down the overall operation of the system Each
59. in the trough of the slider to make small adjustments to the amplitude 6 6 Waveform Offset The CGM 101 includes a waveform offset capability of 2 5 volts Combinations of amplitude and offset that exceed 2 5 volts will cause the waveform to clip For example it is possible to create an unclipped waveform of 1 volt with 1 5 volts of offset but not 2 volts of offset Adjust the waveform offset by dragging the offset slider You can also left click in the trough of the slider to make small adjustments to the offset 6 7 Waveform Selection There are four built in waveforms sine square triangle and sawtooth Select the desired waveform by left clicking on the corresponding waveform selection button Selection of a waveform causes that waveform data to be downloaded from the host PC into the CircuitGear hardware Each waveform data file consists of 256 data points Each data point has a value between 0 and 255 The files for Sine Square Triangle and Sawtooth are supplied with the GUI software in the Source subdirectory with names such as sine dat and so forth You can also load a custom waveform Selecting the Load Custom waveform pops up a file selection box so you can select any waveform See section 6 8 below on creating a custom waveform Figure 3 on page 8 shows the oscilloscope trace of a custom waveform produced by the generator There is a 1 to 2 second download delay after selecting a waveform before the generator begins
60. ine carry load current in the system normally the ground wire does not carry any current Because the neutral is carrying current and because the neutral wire has resistance at any given point in the system there likely will be a small voltage difference between the neutral and ground wires If the ground wire of the oscilloscope is inadvertently connected to the hot wire of the AC line an extremely large short circuit current will flow through the ground connection Eventually a circuit breaker will open a fuse will blow or the short circuit current will destroy a conductor However until that occurs the short circuit current can be in the order of hundreds of amperes This current will destroy the oscilloscope and computer and the resultant flaming debris may cause injury to nearby living organisms including humans It may also start a fire Furthermore connecting the ground lead of the oscilloscope to the AC neutral line causes another problem 1t effectively connects the neutral and ground AC lines at that point Now the neutral current has another path and some of it will flow through the oscilloscope and computer ground leads If this current is sufficient it may damage the oscilloscope and computer Notice that this same situation can occur with equipment that is not transformer isolated from the AC line For example some electronic equipment has a direct connection to the AC line so that the chassis is connected directly to the neut
61. ire The oscilloscope has two connections the input terminal and ground terminal On the front panel BNC connector the inner contact is the input the outer ring is ground The ground connector finds its way to the AC ground line via the third prong on its line cord As shown in figure 14 either lead on the oscilloscope can be safely connected to the positive or negative ter minal of the power supply With proper care to avoid short circuits of the power supply this is a safe measurement situation 11 2 Grounded Power Supply Now consider that the negative terminal of the power supply is connected to its Ground terminal as shown in figure 15 If the ground terminal of the oscilloscope is connected to the ground terminal of the power supply then the circuit is in no danger and will work properly However if the ground terminal of the oscilloscope is inadver tently connected to the positive terminal of the power supply then the power supply will be connected to a short circuit The power supply short circuit will drive current around the ground connections of the power supply and oscilloscope Since lab power supplies are usually current limited to less than an ampere of current the equipment will likely survive However the circuit will not function properly because the power supply is in a short circuited condition To avoid this situation do not connect the positive or negative terminal of the lab power supply to the ground terminal Lea
62. is a sensitive method of comparing the amplitude of two waveforms which need not be sine waves Any waveshape should function in this measurement General Purpose Plotting The XY Mode display may be used for a variety of applications where a plot of some kind is required f Syscomp USB Digital Storage Oscilloscope DSO 101 p E 101 xj File View Tools Hardware Help Syscomp Digital Storage Oscilloscope Vertical Controls Trigger Controls Chan el A a i HE 1 200mV Trigger Mode _ fim en ee Trigger Slope Plus a a ql Manual Trigger Cha el B Trigger Level 0155V a ai Timebase Controls lo amp eb q ss 4 ees 1 r py a i SS 2ms A L yg e 2 Show Measurements Figure 7 Diode Voltage Current Characteristic Figure 7 shows an example The CGR 101 has been configured to plot the voltage current curve of a silicon diode Notice that the diode threshold is around 0 6 volts The vertical scale is voltage measured across a current sensing resistance equivalent to 10mA per division 5 7 Screen Capture It is extremely useful to be able to capture oscilloscope screen shots One or more screen shots may be used to document a particular measurement situation as a record of the measurement or to capture the result for a larger document Because the instrument screens of the CGR Mini are separate windows it is possible to captur
63. is and channel B as the Y axis Select View gt XY Mode to enable the XY display The CGR 101 can simultaneously display both the XY display and the conventional voltage time waveforms which is useful in teaching situations and for debugging purposes If you wish to hide the conventional waveforms and just show the XY display disable the individual channels using the Enable Disable button 11 Lissajous Figures When the two signals are sine waves of the same frequency with a phase shift between them the display is as shown in figure 6 This type of looping display is known as a lissajous figure If the two frequencies different but integer multiples of each other then the lissajous figure will have multiple nodes In the early days of oscilloscopes lissajous figures were used in this manner for frequency measurement The vertical amplifiers of the day could not work at high frequencies so the signals were applied directly to the deflection plates of the cathode ray tube The lissajous figure gave an indication of frequency ratio and relative phase To form a complete lissajous loop the timebase setting must be such that both waveforms show at least one complete cycle Magnitude Measurement If the two signals are exactly in phase the XY plot is a straight line If the two signals are of exactly the same magnitude the angle of the straight line is 45 If the magnitudes are different then the line is at some other angle This
64. ity Center View your current security status and access important settings sound Effect Manager AC97 Audio Control Panel 9 sounds and Audio Devices Change the sound scheme for your computer or configure the settings For a Figure 20 Control Panel Programs obtaining a screen like figure 21 45 E Ei Change or Remove Programs ly Add New Programs Add Remove Windows Components Set Program nd Defaults F Add or Remove Programs Currently installed programs 7 Show updates Sort by Name y 8 AFPL Ghostscript 8 51 5 AFPL Ghostscript Fonts 4 Arcade 3 0 9 blaxxun Contact l burst v3 1 0 19 pao 3 5 Es eMusic 50 Free MP3 offer 48 FTDI USB Serial Converter Drivers B GSview 4 7 Bl Intel R Graphics Media Accelerator Driver for Mobile F iTunes amp J2SE Runtime Environment 5 0 Update 1 amp 125E Runtime Environment 5 0 Update 5 E Launch Manager Y1 0 8 5 Be Macromedia Shockwave Player he Microstar Laboratories Filter Generation re Size 24 14MB Size 5 47MB Size 2 19MB 1 31MB 5 48MB 0 03MB 0 19MB Size Size 33 48MB Size 143 00MB Size 144 00MB Size 1 70MB Figure 21 Add or Remove Programs Figure 21 lists the FTDI drivers so they are installed Similarily the Tcl Tk program for the unit should be shown on the same list under Sy s comp 18 2 3 Obtaining Details of the USB Serial Port 1 On the Add or Remove Programs list of figure 21 find the e
65. ke some time to complete lt Back Nets f Installing Syscomp USB Device Driver Installer Congratulations You are finished installing drivers for your Syscomp device The drivers were successfully installed on this computer You can now connect your device to this computer If your device came with instructions please read them first Driver Name Status Y FTDI CDM Driver Packa Ready to use Y FTDI CDM Driver Packa Ready to use g Welcome to Driver Install h Installing Drivers tup Syscomp CircultGear lol Completing the Syscomp CircuitGear Setup Wizard Setup has finished instaling Syscomp CrcuitGear on your computer The application may be launched by selecting the installed icons Click Finish to exit Setup j Completing the Install Figure 18 Windows Installation Screens 40 i Finished Drivers 17 2 Macintosh Install This section describes how to install Syscomp instruments on a MacBook running OSX These instructions de scribe a one button procedure for software version 1 13 and following You may also wish to check section 18 4 on page 56 which describes setup for a Mac equipped multiple station lab 17 2 1 Checking the Host Machine The Syscomp software is interpreted by the Tcl Tk language interpreter so it is essential that the machine is capable of running Tcl Tk The ActiveState website originators of Tcl Tk i
66. le gt Properties ZA A WN Operate the Connect Using menu to select the COM port that you found previously 8 Select Configure which pops up a Port Settings window Most of the port settings can be left at their default values but the baud rate Bits per Second must be changed to the correct value At this time the correct value is 230400 The correct port settings are Bits per Second 230400 Baud Data bits 8 Parity None Stop Bit 1 Flow Control Hardware RTS CTS Handshaking If you have a version of the scope Tcl program that works correctly with the scope hardware you can verify the baud rate Load that code into a text editor and look for the baud setting Search for a variable baud or a procedure openSerialPort Hit OK and back out to the hyperterminal screen 9 Issue some command from the list in section 13 Type it in followed by the Enter key A good choice is i which should result in a message from the scope indicating its version number 35 14 2 TeraTerm An Alternative to Hyperterminal The Hyperterminal terminal emulator is not available with the Win 7 operating system TeraTerm is an open source alternative and it s somewhat less confusing to use than Hyperterminal To use TeraTerm 1 Download and install the TeraTerm software from Sourceforge http en sourceforge jp projects ttssh2 releases This should create a TeraTerm icon on your desktop 2 Plug in the CGM 101 hardware to an unus
67. le click on the Snow Leopard package Follow the instructions Get the scope hardware and plug into an open USB slot Click on the dock icon SYSCOMP Select OPEN from the popup When the Unable to Connect Examine Settings popup appears select YES When the PORT SETTINGS popup appears select the button dev cu usbserial Click on SAVE AND EXIT If everything was done correctly a CONNECTED rectangle will change from red to green at the top of the open window the CircuitGear GUI If not repeat step 4 again Now we need to set the permissions on the USB port so that all users can access the port To do this start the TERMINAL program In the terminal window type chmod 777 Applications Syscomp CircuitGear V1 15 app Contents MacOS port cfg and hit return Signout as administrator Sign in as a student Put the app in the dock and boot and make sure it works when the hardware is plugged in Acknowledgements Special thanks to John Foster Dorothy Rawek Miles Pierce and Seneca Cunningham John developed the Wave maker program for creating arbitrary waveforms and acted as a beta tester Dorothy provided her MacBook for this investigation Miles acted as a beta tester for the Linux install process and supplied important feedback Seneca showed me how to create a shell script using AppleScript 56 19 Sources of Information 19 1 News Groups comp lang tcl Internet News Group 19 2 Websit
68. lude Mode Auto Normal Single shot Manual Source A or B and Slope Positive or Negative The time at which the trigger occurs is continuously adjustable by adjustment of an on screen cursor so that the operator can display the signal before and or after the trigger event The oscilloscope timebase frequency is derived from a crystal oscillator so it can be expected to be precise and stable The displayed amplitude is determined by 1 resistors and analog digital conversion The vertical preamplifier is gain switched to optimize the signal noise ratio and will accept x10 and x100 scope probes 1 2 Waveform Generator The waveform generator is a direct digital synthesis DDS based device with frequency range between 0 1Hz and 200kHz with a frequency resolution of 0 1Hz The frequency can be adjusted without range switching over that entire range or some part of that range The usual sine square triangle and sawtooth waveforms are supplied with the instrument The generator can also load and produce an arbitrary waveform A GUI based program WaveMaker is available for the construction of arbitrary waveforms 1 3 Digital Input Output The digital I O section includes an 8 bit output port and 8 bit input port Outputs are controlled by 8 GUI buttons Inputs are displayed on 8 GUI indicators In addition there is a pulse generator output which is continuously variable over the frequency 1 Hz to 125kHz with continously adjustable duty cycl
69. methods e Adjust the oscilloscope timebase control to show many cycles of the waveform Then switch to the Spec trum display This will result in a wide range of frequencies on the x axis e The Effective Sampling Rate is shown in a readout at the bottom right corner of the spectrum display This is important the sampling rate must be at least twice the frequencies being analysed to avoid aliasing Put another way there must not be frequency components above the Nyquist rate which is half the sampling rate In the example shown in figure 10 the sample rate is 20kHz The frequency components range from 1kHz to 9kHz below the Nyquist rate of 10kHz gt 5 Harmonics of the square wave extend to much higher frequencies but we assume their amplitude is small enough to be ignored 17 Li A Frequency Spectrum Analysis ah 0 T Vertical Scale E Linear Set Max Szale Ingaribonir 00 TFT Source 2 100 E Sha we A C chanet 1 800 gt 1 500 FET Window fe Reon 200 Hang E sl E pany c 900 oe C Trangalar C 600 Sampling Rabo 195ksfc C 300 Number of Samoles tuuu 3 0 diz Figure 10 Square Wave Spectrum e A sweeping type analog spectrum analyser moves a bandpass filter across a range of frequencies to de termine the spectrum A digital spectrum analyser such as this one divides up the frequency range into a number of bins and then measures the energy in those bins The main oscilloscope display of th
70. n This is useful when setting up a screen display for capture in a document ile View Tools Hardware Help Eal rOscilloscope Channel B A p Trigger He Start C C Documents and Settin B2 Digital 1 0 F Waveform Generator E gt Oscilloscope 52 Console YY trigger cursors JPG Paint el lt sagem Figure 3 Enlarged Screen e Resizing Drag the bottom right corner of the oscilloscope display area to change the size of the display This is particularly useful for teaching and lab demonstrations where the CGM 101 display is projected on an overhead screen as shown in figure 3 5 4 Oscilloscope Mode Triggering In order to present a stable waveform display each display update must start at the same point on a waveform The trigger functions determine how that trigger point on the waveform is selected The trigger controls must meet certain requirements in order to generate trigger signals for waveform capture If these controls are not set properly it is possible that the scope will not capture waveforms and the display will appear to be frozen Alternatively the display may appear to jump between captures without a stable waveform display e Trigger Level The trigger level is marked by a horizontal green cursor with a T symbol at the leftmost edge of the screen figure 4 on page 10 The trigger level may be dragged vertically to set the amplitude on a waveform
71. n press the Spacebar The cursor will change to a camera and you can move it around the screen As you move the cursor over an application window the window will be highlighted The entire window does not need to be visible for you to capture it When you have the cursor over a window you want to capture just click the mouse button and the screen shot will be saved as a PNG file on your desktop The file is saved as PDF in Mac OS 10 3 and earlier Linux Under linux screen capture is handled by the window manager Under Suse Linux Similar to Windows pressing the keyboard Printscreen key captures the entire desktop Alt Printscreen captures the window where the mouse currently resides A popup dialog box prompts you for the file name and location to save the image The image is saved in png format Use the convert command to change it to some other format eg convert foo png foo Jpg As one would expect from Linux there are many other ways to capture a screenshot Google will help you find them 5 8 Aliasing The oscilloscope is a sampled data system It works by taking a series of samples of the input waveform and displaying them However when the signal contains high frequency components compared to the sampling rate the display may be incorrect In theory at least two samples per cycle of the highest frequency present in the waveform are required to reconstruct the waveform correctly Some sampled data systems have a constant
72. ndicate that Tcl Tk should run correctly on platforms with Mac OS X 10 2 There is no mention of requirement for Intel or Power PC processors The first step is to determine that the computer is capable of running this software To do that 1 Click on the Apple icon in the top left corner of the screen 2 Select About this Mac For example on the local Mac machine the Mac information is e Mac OSX 10 5 6 e 2 4GHz Intel Core 2 Duo e 2GB 667MHz RAM The key items are that the operating system is OSX and it s version is later than 10 2 So the software should run on this machine 17 2 2 Installing Software As of August 2012 Apple has added a Gat eKeeper function to OSX Mountain Lion and subsequent operating systems Gatekeeper prevents installing the Syscomp software and generates a Defective Software mes sage You ll need to disable Gatekeeper while doing the download and install A Google search for OSX disable gatekeeper will show the necessary instructions Gatekeeper should be re enabled once the installation is completed and it is verified that the software is operational 1 Start the Mac 2 Plug in the Syscomp CGM 101 hardware The green LED on the hardware should illuminate 3 Point your browser at the Syscomp web site www syscompdesign com 4 Navigate to the Downloads section of the website Download the software for a Windows operating system installation When the software download completes find the download
73. ng Device Port Permissions Change to the dev directory phiscock linux gt cd dev Check the permissions on the tt yUSB ports phiscock linux dev gt ls 1 ttyUSBx crw rw 1 root uucp 188 0 2005 11 07 18 25 ttyUSBO crw rw 1 root uucp 188 1 2004 10 02 01 38 ttyUSB1 lt others deleted gt In this case the owner root has read write access The group that root belongs to uucp also has read write access Others that s you have no access at all To open up the port to user access enter root mode using the su command phiscock linux dev gt su The system asks for the root password Enter it Now you can change the permissions mode for the ports In this case we ll use the chmod command to add read and write permission for others For example the first command below says change the mode of device ttyUSBO to add read permission for others The second command does the same for write permission linux dev chmod o r ttyUSBO linux dev chmod o w ttyUSBO Check the permissions again 49 ls 1 ttyUSBx Crw rw rw CcCrw rw rw That s it 1 root uucp 188 1 root uucp 188 0 2005 11 07 18 25 ttyUSBO 1 2004 10 02 01 38 ttyUSB1 You should now be able to access those ports from user mode Exit from root to user mode Incidentally you may be able to change the permissions by logging in as root and then using the features of the KDE or Gnome desktop to change the permissions 18 3 2
74. ng the Source Code 15 1 Preparation for Modifying the Software The software for the Syscomp instruments is written in the Tcl Tk language The source code is interpreted which means that there is a Tcl language interpreter program present that executes the Tcl source code Consequently you can modify the operation of the program by modifying the source code which we provide We provide as the install an executable which is machine specific ie there are Windows Linux and Mac ver sions which contains the Tcl interpreter and libraries necessary to run the source code The easiest development process is to use that executable to run the source code If you want to change the operation of the code then make a safety copy of the relevant Tcl source code file and edit the source code Tcl file with any text editor You can also run the source code without that executable by executing the command wish main tcl or it s equivalent on your machine in the source code directory If that causes errors the first thing to do is to download the latest version of Tcl from the Activestate website http www activestate com Then try again If there are further error messages concerning the BWidget or Img package you ll need to download those as well using these commands teacup install with recommends BWidget teacup install with recommends Img At that point it should be possible to run wish main tcl and make the graphical user int
75. ngle shot Reset Figure 4 Trigger Cursors trigger hysterysis level TH and a lower trigger hysterysis level TL All three trigger cursors can be dragged vertically TH must always be above the trigger level cursor and TL must be below the trigger level cursor A positive going trigger signal must cross through both the upper trigger hysterysis level and then through the lower trigger hysterysis level Normally there is no need to adjust the hysterysis band and you can leave it at its default settings However for a noisy signal it may help to increase the hysterysis band 5 5 Measurements Screen The Measurements Screen shows cursor and automatic measurements of the most common features of a wave form amplitude and time As shown in figure 5 the Measurements Screen is in a separate window This window defaults to being displayed that is it is displayed when the program is first started The Measurements Screen may be hidden by clicking on the X in the upper right corner of the measurements window It may be displayed by clicking on the menu item View gt Auto Measurements The Measurements Screen shows the Auto Measurements in which the software automatically measures waveform parameters The Frequency and Period readouts are based on the zero crossings of the waveform Consequently the waveform must be periodic and the main display must show at least one complete cycle of the waveform for the frequency and period values to be me
76. ntry System Double click on it to obtain the System Properties screen of figure 22 System Properties xj System Restore Automatic Updates Remote General Computer Name Hardware Advanced Device Manager X properties of any The Device Manager lists all the hardware devices installed on your computer Use the Device Manager ta change the Drivers Driver Signing lets you make sure that installed drivers are compatible with Windows Windows Update lets you set up how Windows connects to Windows Update for drivers Driver Signing Windows Update ar Hardware Profiles Hardware profiles provide a way for you to set up and store Hardware Profiles different hardware OK Cancel Apply Figure 22 System Properties 46 2 Double click on the Hardware tab to obtain the Device Manager screen of figure 23 g Device Manager File Action view Help e gt 0 78 2 38 PUMA Batteries 19 Computer Disk drives a Display adapters 2 DVD CD ROM drives Human Interface Devices 2 IDE ATA ATAPI controllers ga Keyboards Mice and other pointing devices Modems ta Monitors Network adapters 88 Broadcom 802 119 Network Adapter i 88 Realtek RTL8139 810x Family Fast Ethernet NIC E A PCMCIA adapters T a Generic CardBus Controller BES f Intel PCIC compatible PCMCIA controller El Ports COM amp LPT USE Serial Port COM4 ER Process
77. ors 8 Sound video and aame controllers zi Figure 23 System Properties Hardware Device Manager 3 Ensure that the hardware unit DSO 101 oscilloscope WGM 101 waveform generator CGM 101 Circuit Gear CGM 101 etc is plugged into a USB port In the System Properties Hardware panel of figure 23 there should be an entry Ports COM amp LPT Double click on that and it should open to an entry like USB Serial Port COM4 This specifies the COM port that should be selected in the Tcl Tk program in order to communicate with the USB hardware unit 18 2 4 Windows 7 Notes The hardware and software will work correctly under 32 bit and 64 bit versions of Windows 7 operating systems However we have found that certain other serial usb devices can interfere with the operation These hints may help 1 Open Device Manager and maximize the entry Ports COM and LPT Disable the devices that are shown there We know that some Bluetooth devices and a certain Intel program ending appropriately in the phrase SOL can be problems To disable a device right click on the entry in Ports COM and LPT and navigate to the point where you find a disable button 2 Plug in the Syscomp hardware and verify that it appears as an entry under Ports COM and LPT 3 Start the GUI program by double clicking the Syscomp CGM 101 icon on the desktop 4 Ifthe program announces that it cannot connect use the port selection dialog to auto
78. oscope In the DC position the signal is coupled directly into the oscilloscope preamplifier so that all components of the signal are displayed In the AC coupling position the signal is passed through a capacitor so that the DC component of the signal is removed This is particularly useful when you are trying to observe a small AC signal sitting on a larger DC component If the input is DC coupled Increasing the vertical sensitivity increases size of the AC component but also sends the AC component off the screen When AC coupling is selected the AC component can be magnified and viewed without shifting Warning Our recommended maximum input voltage on the AC coupling setting is 40 volts DC Exceeding this may cause damage to the electronic switch that selects between AC and DC coupling You cannot use the AC setting to block DC voltages larger than this value For example in audio tube amplifiers DC voltages of 350 volts or higher are not uncommon If you need AC coupling where the DC component of the signal is larger than 40 volts you should put the coupling in the DC position and connect an external capacitor of the appropriate voltage rating in series with the input The AC coupling position rolls off frequency response below a cutoff frequency which is given by 1 QRC The resistance is IMQ The internal capacitor is 100nF giving a low frequency cutoff of 1 5Hz fe Hide This selection allows one to hide a trace that is
79. ou should see something like this as the last entry in the dmesg printout 48 usb 4 2 new full speed USB device using address 4 usb 4 2 Product USB lt gt Serial Cable usb 4 2 Manufacturer FTDI usb 4 2 SerialNumber 00000001 ftdi_sio 4 2 1 0 FTDI FT245BM Compatible converter detected usb 4 2 FTDI FT245BM Compatible converter now attached to ttyUSBO Unplug the USB cable and run dmesg again and see something like this usb 4 2 USB disconnect address 4 FTDI FT245BM Compatible ttyUSBO FTDI FT245BM Compatible converter now disconnected from ttyUSBO ftdi_sio 4 2 1 0 device disconnected Evidently the USB device is being assigned to device tt yUSBO This shows that the USB device is being recognized by the operating system and assigned to a usb serial port 4 Set the permissions for the USB Serial port The default situation is that root is the owner of the USB serial port tt yUSBO and operation is restricted to root For an ordinary user to access the port the permissions must be changed First we will show how to do this manually in section 18 3 1 However Linux is usually set up so that the permissions revert back to root mode every time the USB is plugged and unplugged and every time the system is rebooted Therefore we need to modify the system so that this is done automatically ie so that the port permissions are set to user mode by default This is shown in section 18 3 2 below 18 3 1 Manually Changi
80. ows USB Serial Port COM3 We decide to move this to COMO Double click on the entry USB Serial Port COM3 This opens a new dialogue box USB Serial Port COM3 Properties Select Port Settings and click on Advanced This opens a new dialog box Advanced Settings for COM3 In the upper left corner there is a scrollbox COM Port Number Use the up down arrows to scroll through the possible COM port assign ments For the new COM port assignment it s best to choose a COM port number 4 or larger Lower numbers may conflict with a USB keyboard or mouse Suppose we decide to move to COMS The scrollbox says COM5 in use Select 1t anyway Click OK Ifa warning pops up that the COM port is in use and asks if you want to continue it s safe to click on Yes Back out through the menues until you have closed the Device Manager panel Re open it and examine the Ports COM amp LPT This time it should read COM5 44 10 Back out to a clean desktop and restart the instrument program This time 1t should connect properly 11 If you are connecting multiple instruments you may need to do this for each instrument However having once done the assignment for a given instrument the operating system associates that instrument with the chosen COM port and connection should be automatic 18 2 2 Checking the Installed Files This section details how to determine that the files are installed correctly This information i
81. producing the waveform During that time other waveform selection buttons are locked out to prevent button mashing Having loaded a custom waveform you can save it to the CGM 101 hardware memory by clicking on the Save Custom button Thereafter clicking on Stored Custom will select that waveform Using Stored Custom avoids having to use the file selector widget to select a custom waveform so it s a shortcut to select a commonly used custom waveform 6 8 Waveform Format Waveform data files are stored in the same directory with the source code On a Windows machine the path to this directory would be something like C Program Files Syscomp CGM101 1 19 Source By convention waveform files end in a dat suffix for example sawtooth dat Other suffixes are also permitted These are plain vanilla text files so they can be loaded into a text editor such as Notepad Each file consists of 256 entries X values Each of these 256 entries is the value of the waveform at that point Y value ranging from 0 most positive to 255 most negative Each entry value is terminated by a carriage return line feed pair A waveform data file can be constructed manually using a programming language eg Visual Basic or from a spreadsheet eg Open Office calc The GUI based program Wavemaker can be used to draw a waveform and convert that drawing into a suitable data filet Wavemaker also has the capability of converting a waveform diagram into a cu
82. puts Y Y Y Y is an integer The digital input sampling period is YYYY x 32usec Example d 5 sets the sampling interval to 160 usec Example d 100 sets the sampling interval to 3200 usec The device will read the digital inputs each sampling period and return them to the host Warning fast sampling periods will swamp the host Set the period to O to disable automatic sampling 33 Waveform Generator WFXXX ZZZ WWW Set Frequency Set the DDS integer to XXXYYYZZZ Each count is 0 2119Hz Notice On the waveform commands there is no space between the com mand string and the numerical argument The parameters XXX Y YY and ZZZ are integer 8 bit numbers i e 0 255 representing the three bytes of the phase value WWW has a weight of 1 ZZZ has a weight of 256 XXX has a weight of 4096 The phase value is calculated as follows Phase value Output Frequency Hz 0 211 Hz where 0 211 is the resolution of the waveform generator Example for a 1kHz output Phase value 1000Hz 0 2119 4719 Setting number 0 x 4096 18 x 256 111 x 1 The command would be WFO 8 111 Note the spaces Set Amplitude Set the waveform amplitude to Y YY Y 4095 x 100 Set Offset Adjust the generator signal DC offset YYYY is an integer between 0 and 4095 The offset integer YYYY is calculated as follows YYYY 4095 ae Vof fset 18 the output offset in volts Description Set Waveform Select the output waveform X is an ascii
83. r Mini VX X The message string terminates with lt cr gt lt 1f gt Oscilloscope Start capture Arms the scope for a capture When the capture is complete the scope will return a data stream with the following format Dt AHALBHBLAH The D character signifies the start of the data stream The t byte is 0x01 if the scope was triggered and 0x00 if an auto trigger occurred AHAL are two bytes representing one 16 bit sample value from channel L are two bytes representing one 16 bit sample value from channel B The data stream is 1024 samples x 2 bytes sample times 2 channels 2 bytes long for a total of 4098 bytes The data bytes are binary coded Start sampling Instructs the scope to start strip chart sampling Request a strip chart sample Returns s if there is no sample ready Otherwise returns 5 bytes SAHALBHBL The S character signifies the start of the strip chart sample AHAL are two bytes representing one 16 bit sample value from channel L are two bytes representing one 16 bit sample value from channel 30 Command Stop sampling Instructs the scope to stop strip chart sampling Command o A B nnnn Channel Offset Changes the DC offset for a scope input channel A or Bis the channel to adjust nnnn is an integer representing the offset from 0 to 4095 The offset integer is calculated as follows Vo se Noffses 2047 pu Where Vo fser is the offset voltage in volts Step is the A D converter
84. ral line of the AC system To safely observe the signals in this device with an oscilloscope the equipment must be isolated from the AC line by a transformer The transformer must function as an isolation transformer the secondary winding must not have an electrical connection to either of the primary leads and the transformer must consist of a separate primary and secondary winding An autotransformer common trade name Variac is an adjustable transformer that is often used for adjusting line voltage An auto transformer does not have an independent secondary winding and cannot be used to isolate electronic equipment from the AC line 11 5 Removing the Ground The potential for a short circuit is reduced if the ground connection is removed from the computer However this is extremely dangerous because metallic connections on the computer such as the shell around a connector are connected to the ground line A connection to the AC line puts those metallic points at line potential presenting a serious shock hazard to the user and possible short circuit if attached equipment is grounded The AC ground connection the third prong on a plug is there specifically to prevent the chassis of the equipment from assuming a potential that is above ground and therefore dangerous to a human operator Re moving that ground connection removes any grounding protection This is a serious violation of health and safety regulations Similarily a battery po
85. rate of the filter 13 6 Waveform Generator The waveform generator controls are shown in figure 8 The Amplitude control is calibrated from 0 to 100 6 1 Setting Frequency The frequency control adjusts frequency between the limits shown in the two buttons at the top and bottom of the frequency slider In the default these limits are 0 2Hz to 200kHz The frequency resolution is 0 1Hz The ac curacy is based on a crystal clock A readout shows the current frequency to a resolution and accuracy of 0 1Hz You can set the frequency by moving left mouse but ton down and drag the slider Alternatively left click on the frequency display and enter a frequency value in the pop up dialog You can also click in the trough of the frequency slider to increment or decrement the current setting 6 2 Setting Sweep Limits To change one of these slider limits left click on it An entry widget appears prompting for a new maximum or minimum frequency Enter a new value and left click on OK or hit lt carriage return gt The new value appears above or below the frequency slider For example if you are sweeping an audio device you can set the maximum and minimum frequencies to 20 000 and 20Hz Then the full scale movement of the slider applies to that range As another example if you are investigating the fre quency response of a 3kHz narrow band active filter you fe Syscomp CircultGear Mint Wareform Generator al Sl xi W
86. reen show show a green colour The unit is operational From now on whenever you double click the program icon the program should start and automatically con nect 17 Installation Details In this section we provide more detail of the installation procedure 17 1 Windows Installation The installation procedure unpacks and installs the Syscomp Graphical User Interface GUI program that inter acts with the hardware It also install two Future Technology Devices International FTDI virtual COM port VCP drivers necessary to communicate with the hardware Screen shots of the install procedure are in figure 18 on page 40 1 Ze Do Un HE W 12 13 Point your browser at the Syscomp web site www syscompdesign com Navigate to the Downloads section of the website Download the software for a Windows operating system installation When the software download completes find the downloaded file Execute that file by double clicking on it After a brief pause the screen of figure 18 a appears Click Next The screen of figure 18 b appears Click Next The Select Start Menu Folder of figure 18 c appears Click Next The Select Additional Tasks screen of figure 18 d appears We recommend enabling Create a Desktop Icon Click on Create a Desktop Icon until a check mark appears next to it Click Next The Ready to Install screen of figure 18 e appears If you are satisfied with the install directories
87. rence of a trigger signal the oscilloscope hardware captures samples into a buffer and then ships them to the host computer for display The complete capture display sequence happens as in a conventional analog oscilloscope several times per second The Main Time Base MTB can be varied between 100mSec division 500 nSec division and 100mSec division in the traditional oscilloscope 1 2 5 sequence 5 3 Oscilloscope Mode Display Refer to figure 2 on page 6 e Vertical Position A waveform may be moved in vertical position At startup the A and B cursors which are the zero reference for the channel are placed at centre screen Using the mouse drag the letter A or B at the right edge of the display area up or down to change the vertical position of the corresponding waveform e Time Cursors It is possible to enable and disable various time and amplitude cursors Right click in the display area A menu appears Toggle Time Cursors Toggle Channel A or B Cursors Grid Left Click to enable and disable vertical cursor lines that mark the time between two locations on screen Left Click to enable and disable horizontal cursor lines that mark the amplitude between two locations on screen Left Click to select the appearance of the graticule grid in the display area enable and disable the display of the grid or change colours of the grid lines Notice that the cursor readout text can be dragged to different positions on the scree
88. s as follows Device dev ttyUSBO e Baud rate 230400 e Data bits 8 Stop bits 1 Parity none 55 5 6 e Handshake Hardware Software not selected Open for Reading writing Apply settings when opening e CR LF line end e Char delay 1 ms In the Input window enter an i character then press the lt enter gt key In the upper display window you should see a message back from the hardware such as Syscomp CircuitGear V1 4 Then CuteCom is connected to the hardware You can send various messages to the hardware and get responses back testing the commands that are documented elsewhere in this manual Acknowledgement Jan Portegijs told us about CuteCom and gave us the correct settings to connect 18 4 Macintosh Lab The following notes are an edited version of install procedure information kindly provided by Ted Johnson of Greenfield College This applies to using the software in a lab environment where everyone using the Mac must be able to start the Syscomp software 1 2 Login as an administrator Open Safari and go to web site www syscompdesign com Select Downloads Select Mac OS X and download When the download is complete drag the icon Syscomp CircuitGear V1 15 or whatever it s named into the Applications folder Open the applications folder check that it is there and drag an alias to the dock Open the folder Drivers Select Mac Select Intel Double click on FTDIUSBSerialDriver Doub
89. s included here for completeness but it should not be necessary to use it 1 Double click on My Computer to obtain a screen like figure 19 p My Computer File Edt View Favorites Tools Help Qe D Osea 0 roes y XK 1 Ee Name type Total size Free Space Comments Files Stored on This Computer GQ Shared Documents File Folder Peter Hiscocks s File Folder Hard Disk Drives SP ACER C Local Disk 26 6 GB 19 0 GB S ACERDATA D Local Disk 8 99 GB 8 99 GB Devices with Removable Storage 080050101 E CD Drive 14 0 MB O bytes Other Be control Panel System Folder Provides options for Figure 19 My Computer 2 Double click on Control Panel obtaining a screen like figure 20 amp Control Panel 3 Double click on Add or Remove Ele Edt wew Favorites Tools Help Ld Q O D Osea E roes i amp 9 Name comments a ACI Fiter Configures speaker configuration and other parameters of AC3 decoder fiter Accessibility Options Adjust your computer settings for vision hearing and mobility S Add Hardware Installs and troubleshoots hardware 13 Add or Remove Programs Install or remove programs and Windows components GQ Administrative Tools Configure administrative settings for your computer Kb Automatic Updates Set up Windows to automatically deliver important updates 2 Date and Time Set the date time and time zone for your computer Sh Display Ch
90. s well sudo chmod 644 etc group lt your password here gt ls 1 etc group rw r r 1 root root 934 2008 05 22 10 17 etc group Special thanks to Gabriel Guillen who loaned me an edubuntu system for this exploration 18 3 7 64 Bit Linux One of the packages in the Syscomp distribution is the Img package The Img package is a Tcl Tk library that is required for the CGM 101 software Currently those libraries are for a 32 bit linux operating system We are in the process of modifying the distribution to accompodate 64 bit linux but in the meantime here is a workaround Delete the existing Img file The best way to do this is to rename it so that you can back out if this procedure fails Once you ve deleted it try running the software If your Tcl Tk distribution has the correct Img library it should run fine If not download and install the ActiveState Tcl Tk distribution for 64 bit linux 18 3 8 Running under 64 bit Sidux Debian based Linux The following notes were provided by Radio College of Canada student Gabriel I am currently running the software on a 64 bit Sidux Debian based linux and have noticed that the img library the so files in Imgl3Lin are 32 bit only This prevents the software from running on any 64bit linux systems This can easily be fixed by installing the img package in 64 bit the package name is libtk img and can be installed by running apt get install libtk img on any Debian based O
91. sampling rate For example audio is typically sampled at 44 1k samples per second In that situation usual practice is to incorporate a low pass filter such that frequencies above 22 kHz are prevented from entering the system Most if not all digital oscilloscopes do not incorporate an anti aliasing filter The sample rate of a digital scope varies over a wide range of frequencies and so the cutoff frequency of the anti aliasing filter would have to do so as well Combined with the bandwidth requirement that is a difficult technical challenge Instead the oscilloscope relies on the operator to recognize when aliasing is occurring and increase the sample rate until the effect disappears A useful strategy in measuring an unknown waveform is to approach it from a high sampling rate aka time base setting and reduce the setting until a readable display appears It is also required of the operator to know approximately the frequency of the waveform that is being observed That is often the case A useful rule of thumb is this the display must contain about 10 samples per cycle of the waveform to reconstruct it For this oscilloscope the maximum sampling rate is 2MSamples second so it can usefully observe frequencies up to about 200kHz The analog bandwidth has been designed to be 200kHz to meet this requirement 2In practice the lowpass cutoff frequency is set to somewhat less than half the sampling frequency to allow for the finite rolloff
92. spectrum analyser includes the rectangular window This window does not shape the time func tion all points on the time record are weighted equally The Hamming Hann and Triangular weighting functions are also available 8 5 Applications Spectrum analysis has a number of applications in electronics and mechanical engineering e A pure tone has no harmonics and will show up on a spectrum display as one single vertical line Distortion of a sine wave will create additional harmonics Consequently a measure of the magnitude of the harmonics is a measure of the magnitude of the harmonic distortion e In a distortion free linear system two separate input tones single frequencies will emerge as the same two tones at the output If the system is distorting non linear then the system will generate other tones at the sum and difference frequencies of the input signals A measure of these extra signals is a measure of the intermodulation distortion e The existence of certain frequencies in a signal may give some clues as to its source For example if a signal contains the power line frequency eg 60Hz in North America 50Hz for the UK then it is probably picking up interference from the AC power line e Power systems frequently manipulate waveforms by chopping them or combining them with other signals Spectrum analysis allows one to measure the harmonic content of a signal which may be specified as a requirement e The analysis of a me
93. start the computer You should now be able to access the USB port without having to change its permissions 18 3 4 Setting Default Port Permissions to User Mode Fedora Core 6 This note applies to Fedora Core 6 kernel 2 6 19 1 2911 fc6 Look in etc udev rules d 50 udev rules for the line KERNEL tty A Z NAME k GROUP uucp MODE 0660 Change the mode value to 0666 18 3 5 Running the Program 1 Change to the directory where the program resides The wish interpreter is required to run the tcl program It is normally included with a Linux distribution so it is probably present on your system You can find out by issuing the which command phiscock linux which wish usr bin wish If this doesn t turn it up use the find command starting at the root directory If it is on the system then add that location to your path phiscock linux find name wish lt much deleted gt usr bin wish 2 Start wish phiscock linux eelab demos gt wish 3 A new small window will appear This is the container for any program that wish executes The cursor remains where the wish command was run 4 Click in that window and run the command o source main tcl using the correct name for the oscilloscope program The oscilloscope GUI should now run correctly There are many other ways to start the program For example the command wish scope 101 tcl substitute the correct name o
94. stom waveform file The waveform could be obtained from a screenshot of an oscilloscope waveform the scan of some image or download from the web for example Wavemaker is available for download from the Syscomp web site Amplitude can be set by the CircuitGear generator hardware so it is best to scale the amplitude between 0 and 255 The CGM 101 includes offset hardware so waveform offset need not be included in the waveform description If the waveform can be described by an equation you can use a spreadsheet to generate the corresponding waveform values Save the column of waveform file values as a csv comma separated values file Then 3 Suffixi Suffixae 4Wavemaker is the work of John Foster 15 examine the file using a text editor such as Notepad to ensure that there are no extraneous characters and the file 1s formatted correctly Then on the graphical user interface for the CGM 101 load the file into the generator by selecting the Load Custom waveform 7 Digital Input Output Section ES Syscomp FirrnitGear Mini Digital Tin Digital KO igital Inputs ________________ Pulse Output Bis z aa uty Cycle sama A Frequency Figure 9 Digital Controls The CircuitGear digital controls are shown in figure 9 These input and output lines can be operated from the GUI controls in figure 9 or they may be controlled by software that communicates with the CircuitGear API applications program interface
95. t 2 2 2 ee ee 23 14 Bloatins Power Supply 3 6 64 4 4 eS oe has BS Mb e OE de ee Oe Sy 25 15 Floatine PowerSupply sic sess dae ee eee Ped bee ee eee SEE eee eee SE 26 16 AC Lin Voltase 2234 oes gad ss oa es dd bees A avd 26 17 Scope Input Compensation Network 0 0 0 0020 00 0 000000 000000 28 18 Windows Installation Screens gt o s ocs sos cees ransu ut s euo aa s dor 40 19 My Computer 04s gone o E A a a a is ORL ee a E a 45 20 Control Panel sgass cg 652 iadi a A 45 21 Add or Remove Proprams s es ss eas be ke Ar e a RS 46 22 System Properties see aoro a aaee d Pa es a A Soe a 46 23 System Properties Hardware Device Manager o a oaoa e e 47 24 Checking that the File has Downloaded aa a 52 25 Directory with Files 20 mice ce werdi eei mutit Emrine AA Heed bs 53 26 USDVIEW 34 ngea bE ee e A A A A a ee E 55 iii Caution Never connect this instrument to the AC line Doing so may result in personal injury and extreme damage to the op erator the instrument and to an attached computer See section 11 on page 24 fl ocone ce aeceana File view Tools Hardware Help Caonerted y Waveform Generator Waveform Generator i photodeti E photodet Triangle Manual Trigger r E Sweep Mode Trigger Mode Logarithmic Auto C Linear Single Shob Reset
96. t be properly configured to be used This is described in the document Seyon Quick Start Guide available for download here http www ee ryerson ca phiscock papers using seyon paf Information on using minicom may be found at the following location Using Minicom and Seyon Chapter 11 of Learning Debian GNU Linux Bill McCarty O Reilly Books 1999 http www oreilly com catalog debian chapter book ch11_07 html 1 Plug the scope hardware into a USB port on the computer 36 2 Run the command dmesg to identify the serial port that the is allocted to this USB device It may be a few seconds before the operating system finishes its allocation so run dmesg repeatedly until you see the serial port number which will be something like t tyUSB1 3 Start the terminal communications program Seyon or Minicom 4 Set the port settings to Bits per Second 230400 Data bits 8 Parity None Stop Bit 1 Flow Control Hardware If you have a version of the oscilloscope Tel program that works correctly with the scope hardware you can verify the baud rate Load that code into a text editor and look for the baud setting Search for a variable baud or a procedure openSerialPort 5 Issue some command from the list in section 13 Type it in followed by the Enter key A good choice is i which should result in a message from the oscilloscope indicating its version number Now you can type in other commands 15 Modifying and Runni
97. t cable Polarizing key Centre bump Strain Relief Active Tech price 1 0 38 Available from MODE Electronics http www mode elec com Distributed by Active Tech Electronics in Canada http www activel23 com Another suitable connector is this one 3M part D89120 0131HK Digikey part MKC20E ND 20 position 2 row 0 1 2 54mm contact spacing ates with 20 way 0 050 spacing flat cable Polarizing key Centre bump Contacts 10u gold plate Digikey price 0 69 Mating strain relief for this connector 3M part D3448 89120 Digikey part MESR20 ND Available from Digikey http www digikey com Any flat cable with 0 050 conductor spacing that will mate with IDC Insulation displacement connector should be suitable for use with these plugs For example 3M 3302 Series Digikey part MCM 20M 5 ND 5 foot length 10 colour repeat clear carrier Digikey price 7 50 The installation of an IDC connector onto flat cable is described here http hubbard engr scu edu embedded guide ribbon Socket Pin or Socket Socket Lead Another connection device that is very handy is the socket pin lead This consists of short length of wire with a socket at one end and a pin at the other The socket fits exactly onto one of the pins of the Mini rear panel connector The pin plugs nicely into a protoboard A similar lead has sockets at both ends of the wire one end can connect to a Mini rear panel connector pin an
98. the amount by which a frequency is to in crease to create each new measurement frequency Or put another way it s the ratio between two adjacent measurement frequencies The frequency step multiplies by a factor rather than adding a constant factor because the frequency scale is logarithmic The network analyser frequency labels can be viewed in fixed point or scientific notation This is selectable under the View menu A fourth slider sets the signal amplitude e The Oscilloscope Display window shows the input and output waveforms which should be sine waves If the signals show clipping reduce the signal amplitude The Start button initiates a frequency sweep Sweeping is slow at low frequencies and speeds up as the frequency increases The display autoscales that is tries to select a scale that just fills the display e The amplitude dynamic range of the VNA is in excess of 50db The VNA automatically adjusts the input signal attenuators of the oscilloscope section to obtain the best possible signal noise ratio without clipping It also uses the full 10 bit range of the oscilloscope A D converters In the frequency response plot of figure 12 the amplitude and phase plots become erratic at high frequencies This occurs because the output signal from the low pass filter is extremely small in that region e The amplitude and phase information may be saved to a csv format data file which can be loaded into Matlab or a spreadsheet
99. tical Mouse Maximum Default Endpoint Size 8 Number of Configurations 1 Vendor ld 0403 Product ld 6001 Revision Number 4 00 Config Number 1 Number of Interfaces 1 Attributes 60 MaxPower Needed 400mA Interface Number 0 Name ftdi_sio Alternate Number 0 Class fi vend Sub Class 0 Protocol 0 Number of Endpoints 2 Endpoint Address 81 Direction in Attribute 2 Type Bulk Max Packet Size 64 Interval Oms Endpoint Address 02 Direction out About Refresh Configure Close Figure 26 Usbview 18 3 10 Terminal Connection under Linux It can be useful to connect to the hardware via a terminal emulator to check the operation of the hardware We used the program Cutecom under Ubuntu Linux It should be possible to install Cutecom under other versions of Linux To install Cutecom under Ubuntu Linux enter the following commands into a terminal window l sudo apt get update 2 sudo apt get install cutecom lrzsz This gets both the CuteCom and 1rzsz packages The latter is not necessary but allows the terminal to sup port zmodem xmodem ymodem file transfer See https help ubuntu com community Cutecom Now we are ready to test the hardware 1 Plug in the Syscomp hardware unit 2 In a terminal window run the dmesg command Look at the last few lines to confirm the connection port We ll assume ttyUSBO 3 Run cutecom 4 Set up the cutecom terminal emulator characteristic
100. tively large square components that rise above the other components on the board The current versions have orange casings On the current design they are designated C61 for Channel A and C81 for Channel B Locate the variable capacitor on the circuit that corresponds to the input channel with the signal With a tiny screwdriver adjust that variable capacitor until the square wave shows the fastest possible rise time without overshoot It is best to use a screwdriver with an insulated shaft because a non insulated screwdriver will connect human body capacitance into the circuit which affects its operation If the screwdriver is not insulated make an adjustment and then remove the screwdriver to see the effect Repeat the same procedure with the second oscilloscope channel Reassemble the unit back in its case If you are using a x10 oscilloscope probe the input capacitance of the scope channels will have changed slightly You will need to adjust a x10 probe for best square wave response If the probe is a x1 x10 switchable unit ensure that the probe is switched to the x10 position Attach it to one of the channels Connect the probe to a square wave source such as the CGM 101 generator output Find the compensation adjustment screw on the scope probe In the economy probes we sell the screw adjust is red and located in the base of the probe cable near the BNC connector In the professional probe we sell the screw adjust is yellow and located in t
101. tware there are no electro mechanical switches or adjustments This makes the hardware very reliable and supports development of custom control software in OEM applications The GUI software is written in the Tcl Tk language The software is open source and entirely in Tcl Tk The GUI software will operate under Linux Mac or Windows operating systems Tcl Tk is an open source interpreted language so reading and modifying the source code is straightforward The applications programming interface API is documented so the hardware can be accessed by other computer programs and languages The only requirement is that the language be able to communicate with a serial port IWaveMaker was developed entirely by John Foster 1 7 Software Updates and Help The CircuitGear manual in pdf format is available from the Help menu Clicking on that menu item automati cally invokes Acrobat Reader The software checks the Syscomp website and advises if there is a later version of the software You can do that manually by selecting Check for Update in the Help menu Alternatively you can configure the software to do that automatically every time it starts Select the Check for Updates on Startup menu iteme The Change Log record of changes with each version is available as a Help menu item 2 Applications In addition to the usual operation of oscilloscope and signal generator here are some possible applications of the CircuitGear unit Logic
102. ve the supply floating 25 Oscilloscope Power Line Ground Power Supply os o FE es Ya p Rea npor Black Ground B a AT e sy fi i u Ground I Green Ground Strap p Figure 15 Floating Power Supply 11 3 Battery and AC Adaptor Power Supplies If batteries are used to power the circuit under test the problematic situation of section 11 2 is not likely to occur because batteries do not normally have a ground connection to the AC line An AC Adaptor is essentially a small transformer coupled DC power supply These are usually supplied with a two prong line cord so there is no ground connection to the AC power line ground The supply is floating so the problem of section 11 2 cannot occur 11 4 Russian Roulette and AC Line Voltage Ground Neutral Hot MN J Oscilloscope and Computer l 4 Input 117VAC i Ground i i HH 1 i ES i To earth Figure 16 AC Line Voltage 7The disadvantages of batteries are a they run down and b they are not current limited A short circuited battery can do significant damage 26 The unsafe situation of an oscilloscope being used to measure AC line voltage is shown in figure 16 The AC line consists of three connections the hot line the neutral line and the ground wire For safety reasons the neutral and ground are connected together and to an earth ground at the system AC distribution panel The hot and neutral l
103. wered laptop computer when disconnected from its line operated charger is not con nected to the ground line of the AC power system so it is less likely to cause the kind of short circuit described in the previous section However it is extremely dangerous to rely on this The laptop may itself become live at the AC line potential which makes it hazardous to the operator and any attached equipment such as a line operated video monitor 11 6 Observation of AC Line Voltages If you must observe line voltage here are the rules e The oscilloscope must be able to cope with the peak value of the input AC voltage The Syscomp DS 101 is certified to reliably accept up to 50 volts on its input terminal A times ten oscilloscope probe increases this by a factor of ten It is absolutely essential to use a probe that can withstand this voltage and it essential to ensure that the probe cannot inadvertently be switched to a times one setting Notice that the peak value of a sinusoidal voltage is 1 41 times the RMS value So a 117VAC line voltage will peak at around 170 volts e There must be no direct connection to the AC line If the equipment is line operated then it must be powered by an isolation transformer see above 27 e It is possible to obtain electronic probes that provide an isolation barrier between the line circuit and the oscilloscope For example the measurement signal is transferred from the AC line side to the oscilloscope side b
104. y means of an optically coupled circuit There is no electrical connection between the oscilloscope and the AC line The signal is transferred over a beam of light This method removes all possibility of short circuiting the line voltage to ground See for example http www powertekuk com 12 Adjustments The oscilloscope has been adjusted before shipping so it should not need adjustment before use These instruc tions are provide for reference purposes 12 1 Input Compensation Capacitors The schematic of the input circuitry of the oscilloscope vertical preamplifier is shown in figure 17 2 5V Input Attenuator Figure 17 Scope Input Compensation Network The two channels are identical Stray capacitance at the output of the voltage divider has the potential for limiting the bandwidth To make the divider frequency independent the resistive divider R1 R2 is accompanied by a capacitive voltage divider VC1 C1 The capacitive divider must be adjusted to have the same division ratio as the resistors This is accomplished by adjusting VC1 To do so remove the circuit board from its plastic case Connect it to the computer via its USB cable and start the host software Apply a square wave input signal to one of the scope channels Adjust the magnitude of the square wave such that it makes a suitable display Adjust the oscilloscope timebase such that the leading edge of the square wave is visible The two variable capacitors are rela

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