jadoon muhammad 04083679 - Introduction
Contents
1. 3 way by 24pins The exact connections to this interface may be seen in the schematics at the end of this document 10 Chapter 1 3 UART The Universal Asynchronous Receiver Transmitter UART controller is the key component of the serial communications subsystem of a computer The UART takes bytes of data and transmits the individual bits in a sequential fashion At the destination a second UART re assembles the bits into complete bytes Asynchronous transmission allows data to be transmitted without the sender having to send a clock signal to the receiver Instead the sender nd receiver must agree on timing parameters in advance and special bits are added to e ch word which are used to synchronize the sending and receiving units When a word is given to the UART for asynchronous transmissions a bit called the Start Bit is added to the beginning of each word that 15 to be transmitted The Start Bit is used to alert the receiver that a word of data is about to be sent and to force the clock in the receiver into synchronization with the clock in the transmitter After the Start Bit the individual bits of the word of data are sent with the Least Significant Bit LSB being sent first Each bit in the transmission is transmitted for exactly the same amount of time as all of the other bits and the receiver looks at the wire at approximately halfway through the period assigned to each bit to d termine if the bit is a 1 or a 02. The sender does not know when the receiver has looked at the value of the bit The sender only knows when the clock says to begin transmitting the next bit of the word When the entire data word has been sent the transmitter may add a so called Parity Bit which may be used by the receiver to perform simple error checking However this feature is not used in this example Then at least one Stop Bit is sent by the transmitter If the Stop Bit does not appear when it is supposed to the UART considers the entire word to be garbled and will report a Framing Error to the host processor when the data word is read Regardless of whether the data was received correctly or not the UART automatically discards the Start and Stop bits If another word is ready for transmission the Start Bit for the new word can be sent as soon as the Stop Bit for the previous word has been sent Because asynchronous data is self synchronizing if there is no data to transmit the transmission line can be idle 3 1 UART communication on the serial port of the ADMC401 Because the serial ports of the ADMC DSP controller are inherently synchronized by a clock signal SCLK the UART interface has to be emulated by software This is 11 achieved as follows Given the baud rate of the desired UART communic tion the serial clock is run at three times this value That entails that for each bit transmitted from the host the ADMC will read three ideally identical bi
3. TransmitBufferNotEmpty is cleared to indicate that the next transmission may be started The routine UARTO Write is the globally accessible entry point which initiates the transmission of the data contained in th low byte of ax0 3 3 5 The receiver routine Read The transmitter routine makes use of three of the status flags in order to ensure the correct sequence of the operations The flag UARTO_ReceiveBufferFull indicates that a complete 30 bit word has been received and is ready to being processed when it is set It is initially polled until a word is received i e the buffer is full At this point the data byte is extracted from the 30 bit word and stored into ax0 The status is reset to indicate that the routine is ready for a new operation Unlike the transmitter the receiving routine has no control over the start ofthe data transfer When a word is received the SPORT generates an interrupt Depending on the status of the flags namely UARTO FirstW ordReceived and UARTO Second WordReceived the service routine undertakes different actions When UARTO FirstWordReceived is cleared indicating that none of the two words has been received yet the word is stored in RX0A SPORTO is set up in the receiving mode for the second half and the status is updated If the flag UARTO SecondW ordReceived is cleared the word goes to the second half RXOB SPORTO is set up in the receiving mode for the next first half and the status 15 upd
4. 2400 115200 baud sec The configuration values of SPORTO are then derived from these constants The header file gives external access to the UART routines It is mostly self explaining The UART routines and header files aren th attached document where the project related software are attached Here only short descriptions of how to implement routines is written the supporting software are in the last section of the report 3 4 3 The initialization of SPORT0 UARTO Init The clock speed of the SPORT is calculated from the configuration parameters You will note that there is a variable called UAR TO Status which represents UART status at every time This is achieved through six flag bits in the variable They are defined after declaration section The actual assembly code may be analyzed The UARTO Init subroutine initializes the SPORTO registers with the appropriate constants Then the status flags are all reset indicating that thete are no pending transmissions and no data has been received At last the routine enables the serial port after clearing any pending and not desired interrupt A call to this routine is necessary for every application before making use of the UART interface 3 4 4 The transmitter routine UARTO Write The transmitter routine makes use of three of the status flags in order to ensure the correct sequence of the operations The flag UARTO TransmitBufferNotEmpty indicates that a previous transm
5. PWM routine swaps the set of registers and may be nested with the serial interrupts with no additional code 18 Chapter 4 UNIVERSAL SERIAL BUS USB 1 An external peripheral interface standard for communication between a computer and external peripherals over a cable using bi serial transmission 2 Universal Serial Bus a plug and play interfac between a computer and add on devices such as keyboards phones and PDAs With USB a new device can be added to a computer without having to add an adapter card or even having to turn the computer off USB supports a data speed of 12 megabits per second and is now being incorporated i in some cell phones which is useful for synchronizing information with a computer or downloading ringtones 4 1 USB 245M 19 4 2 Description The DLP 245M USB provides an easy and cost effective method of transferring data to from a peripheral and host at up to 8 million bits per second Its simple FIFO like design makes it easy to interface to any microcontroller or microprocessor via I O ports To send data from the peripheral to the host computer simply write the byte wide data into the module when is low If the 384 byte transmit buffer fills up or is busy storing the previously written byte the device takes high in order to stop further data from being written until some of the FIFO data has been transferred over USB to the host When the host sends data to the
6. by setting the RFSR bit SPORTO will from now on only acquire data if a new frame sync signal is applied However the current word the 2nd halve is still read When this word is completely transferred a second interrupt is generated and the service routine resets the RFSR bit to the initial condition The UART specification requires the DRO line to b held high SPORTO will only recognise a new frame sync signal when is goes low again which is when the start bit of the next data 15 sent 16 eM 902 Acqs A 86 6345 42 445 Ch3 5 00V 5 00 Y 13 47 32 Typical timing diagram during receive operation Top serial clock SCLKO MID data receive DRO BOTTOM execution of the interrupt service routine UARTO_RX_Isr 3 6 Reliability of the communication Since the process of receiving is due to the nature of the SPORTs trying to synchronize an inherently asynchronous signal to the internal serial clock certain misinterpretations cannot be avoided with these simple three times over sampling routines The falling edge of the start bit may fall anywhere within one cycle of the serial clock The receiver then stores 30 bits onthe falling edges of the serial clock However if the falling edge of the start bit coincides with the falling edge of the clock that bit may be erroneously read in and the whole word is anticipated by one bit This may lead to incorrect interpretation Tests have shown that this occur
7. devices could be found i 0 Each device name will represent one USB I O device that is plugged into your computer If you know that you will only support one USB I O device on your system at one time you can reduce the enumeration code by dropping the for loop and 27 only going through the code once The device name s that are returned from the above code have port number prefixed to the original GUID The port number is related to order of the plug and play devices on your machine and can not be predetermined The device name should look like the following 00000000000000 1 2 b5 157d69 75f8 1 1d3 8ce0 002078 15e61 1 This is the complete device name one will use in order to commuricate with the USB I O device 4 8 Device Communications 4 8 1 Open Device To begin communicating with the USB I O device you must first acquire a handle to it To do this just pass the device name to the CreateFile function This is done in the same manner as opening or creating a file If successful this function will return a handle to the device If the device is not plugged in un powered or opened by another program this function will fail HANDLE hUsbDevice gt CreateFile devicename GENERIC READ GENERIC WRITE 0 NULL OPEN EXISTING 0 NULL 4 8 2 Device Close When your application has finished using the device the device should be closed To do this call CloseHandle with the device handle If you do not close the dev
8. external voltage reference from the REEI91 device to the VREF pin of the ADMC401 The signal is also buffered in one operational amplifier of U9 and used to level shift the applied analog signals on the IF2 connector as well as being connected to the ASHAN and BSHAN inputs to the sample and hold amplifiers In order to operate with the internally derived voltage reference of the ADMCAOI the JP1 jumper must be tied in position 3 so that the SENSE pin is connected to REFCOM 2GND Additionally the jumper JP7 must be left open The ADMC401 provides a 2V reference at the VREF pin that is buffered and applied to the ASHAN and BSHAN inputs The buffered VREF signal is also used in the level shifting circuitry The 1 1 jumper has third setting that permits the SENSE input to be tied to the VREF input This setting is not permitted In summary the appropriate settings for the jumpers JP1 and JP7 for internal and external voltage reference operation are INTERNAL Reference 1 1 in position 3 JP7 open EXTERNAL Reference JP1 in position 1 JP7 closed In addition the reference voltage level is buffered opamp U11A Additionally the voltage reference at the VREF pin of the ADMCAOI is fed to the analog interface connector pin 15 IF2A underneath the processor board where it be 0566 by external circuitry However it is recommended that this signal be buffered prior to use by any other circuitry 2 2 6 External Memory Interfac
9. have the CODE the next step is to make the command packet This is a simply structure of which you just set the fields for a particular command The fields in the command packet are described in the USB IO Data Sheet Simply fill the structure and send it to the USB device with the DevicelOControl function For read commands the DevicelOControl function returns data in the RxPacket The length of the sent packet can range from 8 to 16 bytes The received packet is always 8 bytes long The length data member of the send packet is the length of the data extension The data extension is only required by certain commands If the data extension member is not being used set the data extension length to zero The packet command structure consists of the following elements Command Packet Structure define in C typedef struct _ioPacket unsigned char Recipient unsigned char DeviceModel unsigned char MajorCmd unsigned char MinorCmd unsigned char DataLSB unsigned char DataMSB unsigned short Length length of data extension unsigned char DataExtension 8 VENDORPACKET PVENDORPACKET Command Packet Structure define in VB Public Type PacketStructure Recipient As Byte DeviceModel As Byte MajorCmd As Byte MinorCmd As Byte DataLSB As Byte DataMSB As Byte 29 Length As Int length of data extension DataEntension 8 As Byte End Type C Example This C code example sends the packet and receives the data in t
10. the FIFO s 385 byte transmit buffer is full or busy storing the last byte written Do not attempt to write data to the transmit buffer when TXE is high 15 WR In When taken from a high to a low state WR reads the 8 data lines and writes the byte into the FIFO s transmit buffer Data written to the transmit buffer is sent to the host PC within the TX buffer timeout value default 16mS and placed in the RS 232 buffer opened by the application program Note The FT245BM allows the TX buffer timeout value to be reprogrammed to a value between 1 and 255mS depending on the applicaton requirement also the SND pin can be used to send any remaining data in the TX buffer regardless of the timeout value 16 RD In When pulled low RD takes the 8 data lines from a high impedance state to the current byte in the FIFO s receive buffer Taking RD high returns the data pins to a high impedance state and prepares the next byte if available in the FIFO to be read 17 D7 Bi directional Data Bus Bit 7 18 D6 Bi directional Data Bus Bit 6 19 D5 I O Bi directional Data Bus Bit 5 20 D4 I O Bi directional Data Bus Bit 4 21 D3 I O Bi directional Data Bus Bit 4 4 USB I O Programming 4 4 1 Introduction This document describes how to communicate to the USB I O device 4 4 2 Requirements USB IO Device I O USB Driver USB ready computer running Win98 ME or 2K Microsoft Visual C version 4 0 or better or equivalent
11. there limitations like when you transfer data via parallel port although its fast as compared to data transfer via serial port But you require Many lines like to transfer 8 bits you need 8 lines and thisis applicable only at room level practically for longer distances its not possible similarly in serial communication it goes bit by bit So then came tlie USB it has got highest data transfer rate upto 8 million bits second It appears as virtual comm Port to the system when it is connected Data is transferred like in parallel port but only with one cable The communication through USB is great development in the industry Chapter 2 D S P Module The architecture of a data acquisition system utilizing the processing capability of a DSP chip has existed for many years The ability to do this in a local loop in real time is available today with chips such as the Texas Instruments 1 floating point TMS320C6713 The advantages of such an approach for real time processing are many But also of great interest is the ability for users to stream fast data rates to a host in an economical way The new standard of USB2 2 0 allows high speed data transfer between such a DSP peripheral or standalone and a host PC If such a DSP based data acquisition system could use the highest accuracy data acquisition capability available today and still transfer data at rates up to 480 Mbps it would truly be a breakthrough Current relative accuracy limits for
12. 32 bit compiler for x86 based system or Visual basic Knowledge of C or Visual basic 4 4 3 Overview To communicate with USB IO Driver one must first enumerate thedevice The enumeration of the device returns a device device name is used to open the interface using CreateFile Once you have the handle from CreateFile you can use DeviceIOControl to communicate to the USB IO Device and CloseHandle to close it The hardest part is getting the device name the rest is simply To send commands to the USB IO device simply build a command packet and submit it using the DeviceIOControl functions 4 5 Device Enumeration In order to communicate to the USB device one must first find its device name The device name consists of a number representing a physical port plus the GUID global unique identifier for the device The current USB port and the GUID are combined to form the device name The device iname can change each time you plug in an additional device or plug the device into a different USB port or hub on your computer The typical complete device name looks like 00000000000000 1 2 b5157d69 75f8 1 1d3 8ce0 002078 15e61 1 In Windows XP a typical device name look like WAUS B Vid_OFC5 amp Pidy 1222 00000000 1 b5 157d69 75f8 11d3 8ce0 00207815e61 1 4 6 Device Name Registry Method There are two ways to get the device name The easiest method is to read the device name from the registry When a USB I O de
13. A General Purpose Interval Timer with Prescaler Refer to the ADMC401 datasheet fora full description of all features of the ADMCAOI The ADMC401 PROCESSOR BOARD is intended as a compact highly integrated evaluation and software development platform for the ADMC401 controller The processor board permits access through a UART connection to the Motion Control Debugger software that operat s under Windows 95 or Windows NT The Motion Control Debugger is used to download executable code examine the contents of registers program memory and data memory run executable modules set breakpoints and enable single step operation The processor board is designed for compact size so that all relevant input and output signals are brought to three connector headers underneath the board The processor board contains the following features and components The ADMC401 Single Chip DSP Based Controller External RAM that can be used to expand both the program and data memory xternally A socket for a byte wide EPROM that can be used to boot load internal and or external program and or data memory A 12 96 MHz crystal and associated capacitors to provide the CLKIN frequency A jumper to enable use of the internal power on reset system of the ADMC401 or an external reset provided by a push button switch socket for a serial memory device ROM or E2PROM that may be used for serial boot loading on power up for stand alone operation An isol
14. FO READ CYCLE T6 gt RXF gt RD Active Pulse Width RD to RD Pre Charge Time RXF inactive after RD cycle 21 4 2 2 DLP USB TIMMING DIAGRAM FIFO WRITE mat TXE WR T10 D 7 0 Valid data Descipion min Mex Unt T7 WR Active Pulse Width Data Setup Time before WR inactive Data Hold Time from WR inactive WR Inactive to TXE T12 TXE inactive after RD cycle 80 Ns fe Te m m LN 22 4 3 USB Pin configuration Description BOARD ID Out Identifies the board as either a DLP USB245M or DLP USB232M High for DLP USB232M and low for DLP USB245M 2 Ground 3 RESET In Can be used by an external device to reset the FT245BM If not required this pin must be tied to VCC 4 RESETO Out Output of the internal Reset Generator Stays high impedance for 2ms after VCC gt 3 5v and the internal clock starts up then clamps it s output to the 3 3v output of the internal regulator Taking RESET low will also force RSTOUT to go high impedance RSTOUT is NOT affected by a USB Bus Reset 5 Ground 6 3V30UT Out Output from the integrated L D O regulator It s primary purpose is to provide the internal 3 3v supply to the USB transceiver cell and the RSTOUT pin A small amount of current lt 5mA can be drawn from this pin to power external 3 3v logic
15. P core s internal clock to stabilize The RESET signal is also fed to the UART interface as described previously to permit the Motion Control Debugger to detect a system reset 2 2 3 Serial ROM Interface For normal program development it is envisaged that the Motion Control Debugger would be used to download executable code to the ADMC401 PROCESSOR BOARD However as program development stabilizes it may be required to operate the processor board in a stand alone mode in the target application For this reason the processor board contains an 8 pin DIP socket U7 for installation of a serial memory device that can be used to boot load the program and data memory RAM of the ADMCAOI Either a one time programmable serial ROM device such as the XC1765D Xilinx or electrically erasable devices such as the ATI7C65 E2PROM from Atmel or the 37LV65 from Microchip are recommended These d vices provide sufficient capacity to boot load the entire internal program and data memory space of the ADMC401 If larger areas of memory must be boot loaded compatible higher capacity serial memory devices must be chosen i e XC17128D AT17C128 37LV128 or higher In all cases the application executable file can be converted to a form suitable for the serial memory devices using the MAKEPROM utility that is installed as part of the Motion Control Debugger For both memory devices a three wire connection to SPORTI of the ADMC401 is used 2 2 4 Analog Int
16. UNIVERSITY OF HERTFORDSIRE Faculty of Engineering amp Information Science BACHELOR OF ENGINEERING DEGREE WITH HONOURS IN ELECTRONICS amp ELECTRICAL ENGINEERING Project Report USB CONECTIVITY OF PC WITH DSP MODULE Muhammad Fahd Jadoon April 2005 Chapter 1 Introduction 1 1 Aim To develop a real time communication protocol that will enable to exchange data between and DSP module While the DSP module will performing its usual normal tasks functions It will not be interfered or disturbed during its tasks by the developed communication protocol that is transferring data from DSP module to PC 1 2 Objective 1 Visual Basic for programming on the receive and study the data from DSP module 2 DSP programming in Assembly Language i e for development of DSP drivers to communicate with the USB module 3 To study communication protocol principles for data exchange in real time 4 Development of interface between PC and DSP module 1 3 History Of Communication Communication is part of human life right from the start there have been different methods in the world But with the passage of time as the technology advanced the method of communication also changed But in 21 century with the advent of micro processor the whole scenario changed The data transfer became more more easy First it was transfer from serial parallel port or access through data bases but all these have
17. ated If none of th above conditions is true then the currently received word was received before Read has processed the previous words In that case the word is removed from the SPORTO receive register and is lost for any further operation The routine UARTO Read 15 the globally accessible entry point which waits for data to be received over SPORTO It then extracts the data byte and stores the in the low byte of ax0 15 The software section also contains the codes for generating the PWM The comments are given in the codes where they are required to explain the n cessary steps 3 5 Receiver configuration As mentioned the interface requires a different SPORT configuration for each halve of the received word The reason for this is explained by means of a measured timing diagram such as shown in Figure The represented relati n between serial clock and data receive line is only indicative since data is transmitted asynchronously from the host The receiver is initially set up with the RFSR receive frame sync required bit equal to zero This entails that the frame sync signal tied to data receive line is required only at the beginning of the data acquisition Therefore a continuous stream of data would be read in When the first halve is read SPORTO generates an interrupt the first glitch of the bottom track in the figure below and starts reading the next bits The interrupt routine now changes the configuration
18. ated UART interface to the Motion Control Debugger The signals are optically isolated from the remainder of the processor board The AD7306 is used to drive the appropriate signals on the 9 way UART connector An input power supply connector that accepts S V VDD 5V XAVDD GND The 5V is used to drive the digital circuits and the analog portion of the ADMC401 The 5V supplies are used for the analog interface circuits of the processor board An on board 5V to 5V dc dc converter that provides an isolated 5V supply for the UART interface circuit Analog interface circuits that correctly offset the analog input signals to the ADC inputs of the ADMC401 Eight independent analog interface circuits are included one for each ADC channel of the ADMCAOI An on board precision 2 048V voltage reference using the REF19T that can be used to provide the input reference for ADCs of the ADMCAOI The reference voltage is also brought to the connector underneath the board Jumpers that permit setting of the PWM polarity enabling or disabling of the PWMTRIP input and enabling or disabling the serial memory device in the socket Additional jumpers are included on the board to allow selection of either internal or external voltage reference for use with the ADC system of the ADMCAOI Three socket blocks underneath the processor board th t permit access to all of the input and output signals of interest The three sockets comprise two
19. data acquisition are 24 bit or 60 ppb This combined with data rates as high as 100 000 measurements per second would provide breakthrough performance A system architect could use such performance either in a local or on a stream basis via the USB 2 0 communications link This freedom of choice would solve many measurement challenges in industrial systems For example such an embedded system could perform signal processing and real time control independently of the host or under the control of the host processor Other key advantages of this type of system would be Plug amp play features of USB 2 0 provide a quick and easy way to have the data acquisition system up and running Galvanic isolation can be implemented to protect the host computer from ground loops and voltage transients a capability not often found on data acquisition products Galvanic isolation also h lps to adhere to the tough CE requirements of EN50082 1 1998 Programs can be downloaded via USB 2 0 to on board memory or flash The ideal operation of this real time data acquisition system would allow simultaneous operation in real tim of all measurement subsystems at high throughput rates and high accuracy The TMS320C6713 floating point DSP could read data from 24 bit sigma delta A Ds write data to 24 bit sigma delta D As do digital input output control operations or use on board 32 bit up down counter timers all simultaneously and in real
20. digital sockets 1 and IF3 and one analog socket IF2 2 2 FUNCTIONAL DESCRIPTION OF PROCESSOR BOARD This section is intended as a functional description only of the major elements of the board 2 2 1 UART Interface A UART interface to the Motion Control Debugger is provided on the ADMC401 PROCESSOR BOARD 9 way D type connector In order to separate the ADMC401 and any power conversion stage used in a complete motor drive system the interface is optically isolated from the remainder of the processor board The Motion Control Debugger communicates through serial port 1 SPORTI of the ADMC401 using the DRIB and DTI pins In addition the ADMC401 reset signal ICRESET is sent to the UART interface to ensure that a processor board reset is detected by the Motion Control Debugger The three signals DT1 and ICRESET are optically isolated using two HCPL0630 dual isolators U4 amp U5 The signals DTI and ICRESETare considered as outputs as these signals are sent from the processor board to the debugger These signals are applied to one opto isolator Conversely the signal DR 15 considered as an input as it is received by the processor board This signal is isolated using the second isolator U4 The secondary supply for the optical isolators 15 produced onthe processor board by the NMEO0505S power supply isolated 5V to 5V dc de converter The ADMC401 PROCESSOR BOARD also contains an AD7306 transce
21. e Provision is made on the processor board to expand both the prograny and data memory externally to the ADMC401 There are three sockets U12 U13 and U14 on the processor board into which external RAM chips may be inserted The processor board is designed to operate with CY7C 199 memory devices from Cypress or AS7C256 memory devices from Alliance The external memory is capable of zero wait state operation The three external memory chips are each arranged as a 32K x 8 bit memory array When connected in this way the lower 16K is recognized as data memory and the upper 16K is recognized as program memory The selection is made by using the data memory select DMS strobe as the upper address line to the memory devices Of course not all of this space is available because areas of the external memory devices whose addresses are identical to the internal memory space of the ADMC401 are unused on the external memory chips The three memory devices U12 013 and 014 are used by external program memory where U12 provides low byte 00 07 U13 provides the middle byte D8 D15 and U14 provides the high byte D16 D23 of the external 24 bit program memory word For external data memory accesses only U13 and U14 are used since the 16 bit data memory word is read writt n on data lines D8 D23 These external RAM chips provide an additional 12K x 24 bits of external program memory RAM This program memory block is arranged as one contiguous add
22. e This string contains the device name of the last USB IO device loaded 3l Chapter 5 Results The results and the soft wares are attached there are two forms and three bas files These detect the device connected at the USB port of the hub load it drivers and then communicate with it in order to collect data The comments before the start of every statement explain the action of the step 32 6 Conclusion The design of Interface between PC and DSP module based on the Visual basic has been shown in this report There are different ways to design an interface including the other languages like in C Java Assembly Language The first and foremost thing in order to develop an interface 15 to get the knowledge of the hard ware involved DSP board that we have used belongs to ADMC 2100 family This Family has got high transfer rate as compared to other DSP modules It has got UART connected to it through nine pin D type connector and it is isolated from rest of the board The drivers of the DSP and UART are loaded and in return these run the DSP module and the UART that helps to transfer data via USB After the hardware is connected software is developed and implemented one by one First of all drivers for DSP and UART have been installed and then program developed in VB tool to communicate between PC and DSP module This program contains two Forms and three modules bas files In data collect form it get the name of
23. erface The ADMC401 PROCESSOR BOARD permits up to eight analog inputs to be fed from the User Interface Connector IF2A pins l to 8 to the eight ADC channels of the ADMC401 All eight analog inputs at th IF2A User Interface Connector may range from 2V to 42V A Gain Calibration input may also be fed from pin 9 of the IF2A connector to the Gain pin on the ADMCAOI There is a separate interface circuit for each of the eight ADC channels of the ADMCAOL included on the processor board These analog interface circuits convert the nominally 2 V signals at the IF2 interface connector to signals centered on the ADMCAOI reference voltage level either the internally derived 2 0V level the externally provided 2 048 level The analog interface circuits consisting of high performance perational amplifiers and precision resistor networks effectively offset the analog inputs by the reference voltage level Three AD8044 quad operational amplifiers are used U8 U9 amp U11 for the analog interface and are configured as summing unity gain stages U8 is used to interface the VINO VINI VIN2 and VIN3 analog inputs U9 is used to buffer the VINA VIN5 VIN6 and VIN7 inputs The G input is also level shifted and buffered in the same way using one operational amplifier of U11 This is applied to the GAIN compensation input pin of the ADMC401 Precision 10 kW resistor networks RN5 are used for input and feedback resistors to ensure accurate
24. gain matching of all channels In addition 270 pF feedback capacitors are used to provide simple low pass filtering with a 59kHz cut off frequency on all analog inputs The analog inputs are applied to the ADMC401 in a single ended fashion so that the inverting inputs to the sample and hold amplifiers of the ADMCA01 ASHAN and BSHAN are connected to a buffered version of the reference voltage A representation of the analog interface circuit for one of the ADC channels is shown in Figure 2 2 As can be seen in the schematics at the end of this document each analog input stage also contains a small RC filter at the operational amplifier output Figure 2 2 2 2 5 Reference Voltage Generation The ADMC401 PROCESSOR BOARD contains an external voltage reference the REF191 U10 that can be used to provide a precise 2 048V output The evaluation board can be configured to operate from either the internal ADMCAOI generated or the external voltage reference Two jumpers control the selection of either internal or external voltage reference Jumper JP1 can be used to tie the SENSE pin of the ADMCAOI to either the AVDD or GND levels Connecting SENSE to AVDD JP1 in position 1 selects external voltage reference operation In this mode th ADMCAOI accepts an input voltage reference at the VREF pin In order to connect the external voltage reference to the ADMCAOI on the evaluation board it is necessary to insert the JP7 jumper This connects the
25. he same packet that was sent to it On error it returns 1 int UsbCtrl PVENDORPACKET pPacket ULONG nBytes BOOLEAN Success Success DeviceloControl hUsb IOCTL USBIO WRITE PACKET pPacket 8 pPacket gt Length pPacket 8 amp nBytes NULL if Success Il nBytes sizeof VENDORPACKET if Verbose MessagePopup UsbCtrl Error DeviceloControl call failed retum 1 else return 0 VB Example This VB code example sends the packet and receives the data in the returned value of the function Sends the USB packet to the device Function SendPacket ByRef TxPacket As PacketStructure As PacketStructure Dim IpResult As Long Dim RxPacket As PacketStructure TxPacket Recipient 8 always 8 TxPacket DeviceModel 18 always 18 If 0 DeviceloControl hDevice CODE SEND PACKET TxPacket 8 TxPacket Length RxPacket 8 IpResult 0 Then MsgBox SendPacket DeviceloControl Failed Exit Function End If SendPacket gt RxPacket End Function 4 9 2 Registry Keys The following is a list of registry keys that the USB I O driver adds to the registry To access the registry run RegEdit exe from the command prompt The registry keys are located at 30 HKEY_LOCAL_MACHINE System CurrentControlSet Services US B Parameters USB I O Registry Keys DebugLevel Used for debugging should always be zero BootUpTest Used for testing should always be zero DeviceNam
26. ice you will not be able to access it again without re setting the device port CloseHandle hUsbDevice 4 9 Device Communications 4 9 1 Device I O Control The DevicelIOControl function provides the communication method between the users and the device This function accepts CODES and users buffers that are passed to the device driver and eventually the USB device success DeviceloControl hUsbDevice IOCTL USB SEND PACKET amp TxPacket 8 TxPacket gt Length amp RxPacket 8 amp nBytes NULL The CTL Codes are predefined codes that describe the action to take place There are many different codes but for our purposes we are only concerned with the send packet code Below is CODE generation shown in C define CTL_CODE DeviceType Function Method Access 28 DeviceType lt lt 16 Access lt lt 14 Function lt lt 2 Method define METHOD_BUFFERED 0 define FILE ANY ACCESS 0 define FILE DEVICE UNKNOWN 0x00000022 define FTDI USBIO IOCTL VENDOR 0x0800 Vendor defined define IOCTL USB WRITE PACKET CODE FILE DEVICE UNKNOWN FIDI USB IOCTL VENDOR 10 METHOD BUFFERED FILE ANY ACCESS The above code generates a CODE of 0x222028 You can just use this number instead for using the above code see below For VB code use amp H222028 define IOCTL USBIO SEND PACKET 0x222028 for C Const CTL CODE SEND PACKET amp H222028 for VB Once you
27. if required 7 Ground 8 SLEEP Out Goes Low after the device is configured via USB then high during USB suspend Can be used to control power to external logic using a P Channel Logic Level MOSFET switch 9 SND WUP In If the DLP USB245M is in USB suspend a positive edge on this pin WAKEUP initiates a remote wakeup sequence If the device is active not in suspend a positive edge on this pin SEND causes the data in the write buffer to be sent to the PC on the next USB Data In request regardless of how many bytes are in the buffer 10 VCC IO In 3 0 volt to 5 25 volt VCC to the UART interface pins 10 12 14 16 and 18 25 When interfacing with 3 3v external logic connect VCC IO to the 3 3v supply of the external logic otherwise connect to VCC to drive out at 5v CMOS level This pin must be connected to VCC from the target electronics or EXTVCC 11 EXTVCC In Use for applying main power 4 4 to 5 25 Volts to the module Connect to PORTVCC if module is to be powered by the USB port typical configuration 12 PORTVCC Out Power from USB port Connect to EXTVCC if module is to be powered by the USB port typical configuration 500mA maximum current available to USB adapter and target electronics if USB device is configured for high power 13 RXF Out When low at least 1 byte is present in the FIFO s 128 byte receive buffer and is ready to be read with RD RXF goes high when the receive buffer is empty 14 TXE When high
28. ission is still in progress when it is set It is initially polled until there are no pending transmissions i e the buffer is empty At this point the demanded 14 transmission may be initiated The above mentioned flag is set and two other bits namely UARTO FirstWordTransmitted and UARTO_SecondWordTransmittedyare cleared to indicate that none of the two words has been transmitted yet The data byte in ax0 is processed to generate the two 15 bit words to be sent The next action that is required is to send the first word and update the status flag UARTO FirstWordTransmitted by setting it which indicates that the first word has been transmitted For correct operation under all conditions these operations may not be interrupted by any other service routine This is ensured by the adopted sequence of disabling any interrupt performing the two actions and enabling int rrupts after that again The SPORT will generate an interrupt as soon as it is ready to transmit another word This will call the interrupt service routine UARTO TX Isr which provides for sending the 2nd word after checking the status Again updating the status and sending the word is not interruptible by means of the sequence described above This time the flag UARTO SecondWordTransmitted is set The SPORT will generate another interrupt when ready for the next transmission Now since the status indicates that both halves are sent no further transfer is required and the UAR TO
29. iver that converts the TTL signals to the appropriate 10 V levels suitable for the UART connection to A standard PC serial cable be used to connect from the 9 way female socket of the processor board to the appropriate COM port of the PC The baud rate and COM port to be used on the PC may be set from the ADMC401 Comm Config software that is part of the Motion Control Debugger A functional block diagram of the UART interface circuit is shown in Figure 2 1 The direction of the three signals is indicated in the figure Refer to fullschematics at the end of this document for the full circuit Recall that the secondary supply for the optical isolators and the AD7306 is derived on the processor board by the isolated dc dc converter the NME0505S U1 Figure 2 1 2 2 2 Power On Reset Circuit The ADMC401 contains an integrated power on reset POR circuit that provides an output reset signal from the ADMC401 on power up and if the power supply voltage falls below the threshold level The ADMC401 may be reset using the internal power on reset circuit by connecting pin to the RESET pin jumper in 1 2 position or alternatively from an external source using the RESET pin jumper JP3 in 2 3 position By pressing the 51 push button switch the voltage level at the RESET pin is brought below the threshold level Resistor R9 and capacitor C26 limit the rise of voltage at the RESET pin to allow the DS
30. kResult szKey 0 0 szBuffer IBuffSize Query the value RegCloseKey phkResult Close the Key If IResult ERROR_SUCCESS Then GetReg Value szBuffer return key value End If Exit Function 4 7 Device Name Enumeration Method The second method to get the device name is two use Windows device manger To do this one calls a function in the setupapi dll Simply poll the device manger with the USB I O GUID for all the devices that match the GUID given The device manger will return the device names forall the devices currently available on your system This is the better way of getting the device name It allows the user to use multiple devices on the same computer The draw back is that it is little more complicated C Enumeration Example Below is a C example using this enumeration method Use the DEFINE GUID macro to build the GUID B5157D69 75F8 11d3 8CE0 00207815E611 DEFINE GUID USB 0xb5157d69 0x75f8 0x11d3 Ox8c OxeO 0x0 0x20 0x78 0x15 0xe6 Ox 11 This GUID is passed to SetupDiGetClassDevs which returns a handle to the device The enumeration functions are found in the setupapi library HDEVINFO hinfo SetupDiGetClassDevs amp USB 001 NULL NULL DIGCF PRESENT DIGCF_INTERFACEDEVICE 26 The first argument identifies the interface you re looking for The flag bitsin the last argument indicate that you are looking for the interfaces exported by the USB I O device Once you have a handle t
31. o the device information set you can perform an enumeration of all the devices that export the particular interface you re interestedin See Microsoft function documentation for more information on setupapi dll library functions Poll the device manager till there are no matching devices left int i Cstring Devices 10 an array of cstrings for DWORD 1 0 i 1 SP INTERFACE DEVICE DATA Interface Info Interface Info cbSize sizeof Interface Info Enumerate device if ISetupDiEnumlInterfaceDevice hInfo NULL LPGUID amp USB GUID i amp Interface Info SetupDiDestroy DevicelnfoList hInfo return i DWORD needed get the required lenght SetupDiGetInterfaceDeviceDetail hInfo amp Interface_Info NULL 0 amp needed NULL PSP_INTERFACE_DEVICE_DETAIL_DATA detail PSP INTERFACE DEVICE DETAIL DATA malloc needed if detail SetupDiDestroyDeviceInfoL ist hInfo return 1 fill the device details detail gt cbSize sizeof SP_INTERFACE_DEVICE_DETAIL_DATA if ISetupDiGetInterfaceDeviceDetail hInfo amp Interface Info detail needed NULL NULL free PVOID detail SetupDiDestroy DevicelnfoList hInfo return i char name MAX PATH strmcpy name detail gt DevicePath sizeof name free PVOID d tail Devices i keep a copy of each device name end of for loop After this code runs you end up with a list of device names or NULL if no
32. peripheral over USB the device will take RXF low to let the peripheral know that at least one byte of data 15 available The peripheral then reads the data until RXF goes high indicating no more data is available to read By using FTDI s virtual COM Port drivers the peripheral looks like a standard COM Port to the application software Commands to set the baud rate are ignored the device always transfers data at its fastest rate regardless of the application s baud rate setting USB devices transfer data in packets If data 15 be sent from the PC a packet is built up by the application program and is sent via the device driver to the USB scheduler This scheduler puts a request onto the list of tasks forthe USB host controller to perform This will typically take at least 1 millisecond to execute because it will not pick up the new request until the next USB Frame the frame period is 1 millisecond There is therefore a sizeable overhead depending on your required throughput associated with moving the data from the application to the USB device If data is sent byte at a time by an application this will severely limit the overall throughput of the system as a whole It must be stressed that in order to achieve maximum throughput application programs should send or receive data using buffers and not individual characters Microcontroller DLP USB245M USB B Connector 20 4 2 1 DLP USB 245 TIMING DIAGRAM FI
33. ress space starting at address 0x 1000 Program memory read or write accesses in the address range 0x1000 to Ox3FFF 1 this external memory The following signals are all brought directly from the ADMCAOI to the User Interface Connector IF1 for easy access and external expansion if required The address lines ADO to AD13 The data lines 00 to D23 The memory select lines BMS DMS PMS The read write strobe Hnes WR RD The bus request grant control lines BGH BG BR The powerdown pins PWDACK PWD The mode select pins MMAP BMODE The settings of these jumpers are described in Table 2 1 PI Permanently Disable PWM outputs Enabled PWMTRIPB state from Interface Connector Table 2 1 2 7 Interface Connectors In order to create as compact n evaluation and development board as possible all input and output signals are brought to three interface connectors underneath the processor board Two connectors IF land are dedicated to digital signals and the third IF2 is reserved for analog signals This three connector interface will be used in future processor boards for future motion control products from Analog Devices Therefore many of the pins on the connectors for the ADMC401 PROCESSOR BOARD are unconnected n c These pins are reserved for other functions in future products Interface connectors IF and IF3 are both 3 way by 30 pin connectors Connector IF2 is
34. s with a probability of approx 80ppm when data is continuously sent The probability decreases drastically if delays are inserted between the single bytes to be transmitted In order to avoid unacceptable behaviors it is recommended to echo the received data to the host which should check for eventual misinterpretation If a more robust transmission is required the three times sampling is not suited One may think of increasing the sampling factor to 5 or 6 This entails more complicate routines since more words have to be read and sent for each byte but on the other hand allow for 17 error detection and correction by testing more samples for each bit and implementing some kind of majority tests 3 7 Interrupt configuration and context swapping in ADSP 2100 As mentioned in preceding sections it has been decided to use the primary set of registers in the interrupt service routines and to manually save the context rather than swapping to the secondary set provides with the ADSP 21xx core The reason for it is that serial communication tasks are normally strongly linked to mainoop routines Since there is only one register that 15 required by the service routines the overhead created by the context saving instruction is not critical The advantage of this approach is that the option of nesting interrupts such as PWM service routines with the serial communication routine is left to the user of this interface As shownin the example the
35. the HOST CONTROLER ROOT and open a connection to it After that it get node information and save this information in our data table to discover the connected device to the ports of ROOT HUB Then the control is passed to display form once all the information has been collected and that DISPLAY FORM will show required information 33 Bibliography Related Documents and Web sites Universal Serial Bus Specification www usb org Microsoft Development Networwww msdn microsoft comm Delcom Engineering Web Site www delcom eng com Analog devices user manual IEE journals and tutorials 34
36. the header file uartO h which provides function like calls to the routines The routines require some configuration constants which are declared in a dedicated section of the main include file main h that comes with every application note In the following sections each routine is explained in detail with the relevant segments of code which is found in either uartO h or uart0 dsp For more information e g about register use see the comments in those files The following table 3 2 summarizes the set of macros defined in this library Initialisation UARTO Init Read Byte from Host UARTO Read register Write Byte to Host UARTO Write register or constant Table 3 2 13 There is an initialization routine UARTO Init that has to be invoked priorto using the interface After that data bytes may be sent or received from the host by calling the routines UARTO Write or UARTO Read respectively 3 4 2 The UART interface The library may be accessed by including the header file uartO h in the application code as was already explained in the previous section It expects some constants defined in main h These are two parameters that the user may want to modify namely namely the frequency of the crystal that is used on the board CLKIN defaults to the value on the evaluation board of the ADMC331 and the desires transfer speed The constant UARTO Baudrate defines the latter Common values for this parameter are 1200
37. time Scalability of these operations would also be possible by adding system boards with common clocks and triggers Data would be either sent to the host using USB 2 0 or shared between processes with on board 50MB per second LVDS ports An additional benefit of the USB 2 0 communication mechanism would be that power or system operation is available as part of the connector mechanism 2 1 DSP Board The ADMC401 PROCESSOR BOARD is a compact highly flexible evaluation and development board for the single chip DSP based high performance motor controller the ADMC401 The ADMC401 motor controller provides the following significant features 26 MIPS Fixed Point 16 bit DSP Core 2K X 24 Bit Internal Program Memory RAM 2K X 24 Bit Internal Program Memory ROM IK X 16 Bit Internal Data Memory RAM 14 Bit Address Bus and 24 Bit Data Bus for External Memory Expansion 8 Input 12 Bit Pipeline Flash Analog to Digital Converter inputs with lt 2ms total conversion time A Three Phase 16 bit Center Based PWM Generator An Incremental Encoder Interface Unit with Companion Encoder Event Timer 12 General Purpose I O Lines Configurable as Inputs Outputs Interrupt Sources or PWM Trip Sources An Internal Power On Reset System POR A Two Channel Event Timer Unit A Peripheral Interrupt Controller Two Synchronous Serial Ports Two Variable Frequency 8 Bit Auxiliary PWM Outputs A 16 Bit Watchdog Timer
38. ts The software then provides for extracting the middle of the three which is considered to be the correct value and to assemble the extracted bits into a byte of data Similarly for each bit that i to be sent to the host the ADMC is required to repeat its value for three SCLK cycles The protocol that is used in this example requires one start bit followed by eight data bits one byte and one stop bit No parity bit is used That means that for each data byte the serial port will send or receive 30 bits as depicted in Table 3 1 The routines described herein provide for converting a byte into this format and vice versa Data format Start Data Byte 8 bits Stop for SPORTO Byte represented by 24 bits Table 3 1 3 2 Serial port configuration Since each byte of data to be exchanged on the serial interface actually requires 30 bits to be transmitted or received it has to be split in the SPORT registers into two halves of 15 bits The word length SLEN is therefore set to 141 The data is right justified into bits 0 to 14 of the transmit and receive buffer registers The recommended configuration for the transmitter is alternate framing mode internally generated and active low frame sync signal The serial clock has of course 0 be generated internally too The receiver is set up differently for each half The first half is received in unframed mode alternate framing For the second word external frame sync is required acti
39. ve high 3 3 Hardware requirements The serial interface consists of the transmitter data line pin DTO of the ADMC331 and the receiver data line pin DRO on the ADMC33 1 In order to generate interrupts the receiving data line DRO must be tied also to the RFSO pin of the ADMC331 If shifting from the TTL level OV and 45V to UART levels 10V and 10V is required for instance when communicating with a PC some additional hardware is necessary The schematic shown in Figure 3 1 makes use of the AD7306 converter Also the DSP 5106 15 isolated from the other device by means of standard opto couplers such as the HCPL0630 Of course the AD7306 is only needed if RS232 voltage levels are required The isolation is also optional The routines presented here could be used to implement an SCI UART type interface between processors at TTL voltage levels In that case only pull up resistors on and DRO RSFO still has to be tied to DRO are required 12 HCPLD630 3 HCPLD630 VDD1 5V ISOLATED FROM VDD Figure 3 1 3 4 The UART Library Routines 3 4 1 Using the UART routines The UART routines are developed as an easy to use library which has to be linked to the user s application The library consists of two files The file uart0 dsp contains the assembly code for the required subroutines This package has to be compiled and can then be linked to an application The user simply has to include
40. vice is plugged in to your computer the OS detects it and loads the driver When this driver loads the device name is stored in the registry Then the user just reads the name out of the registry This method has one disadvantage It can t be used when more than one USB I O device is plugged in to your computer because only the last device name will be recorded in the registry To use the registry method simply open the registry key query the value and close the registry key The registry key name is Device Name and the path is HKEY LOCAL MACHINES ystemNCurrentControlSetNServicesV USB Parameters 25 You can uses regedit exe to find the entry It also a good place to copy the GUID from so you don t any mistakes VB Registry Example Here is an example in Visual Basic on how to read the device name from the registry DIM DeviceName as string DeviceName GetRegValue HKEY LOCAL MACHINE _ System CurrentControlSet Services US DeviceName GetReg Value Gets the Key value in the registry given a registry key Function GetRegValue hKey As Long IpszSubKey As String szKey As String As String Dim phkResult As Long IResult As Long Dim szBuffer As String IBuffSize As Long Create Buffer szBuffer Space 255 Allocate buffer space IBuffSize Len szBuffer Set the length RegOpenKeyEx hKey IpszSubKey 0 1 phkResult Open the Key get a handle to it IResult RegQuery ValueEx ph
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