DTMF Signal Controlled House Monitoring System (HMS)
Contents
1. MIC Sound Signal Sound monitor 1 t MIC gt Line Status Vv Heating gt Control A DTMF be LINE KO al Decoder Digital signal _ PIC Controller Alarm r PIC Sound Signal e Control v l q _ Auto Temperatur answer Answer signal emp eran A p monitor circuit Security Watch dog Fig 1 Structural functional scheme 3 2 Discussion of the Structural Functional Scheme The interaction between the user and device take place through the simple telephone line This medium is capable for the transmission of the all control signal and information When the user is calling up there is an AC voltage in the circuit of approximately 24V According to the line status connection PIC determines that there is a call and after some time hook up the line This is done through the auto riser circuit When the call is finished it puts down the line After the line is hooked up DTMF decoder sends digital 4 bit signal that corresponds to the certain bottom to the controller According this digital signal the controller performs some operations Some of these operations are followed by the PIC sound signals to line The controller can enable sound monitor connected to the microphone at the room Then the obtained sound signal is sent up to the line in the similar way as the PIC sound signal Also the PIC can some enable heating device and hold it enabled until the time when it will be o2. DTMF Input od DTMF Decoder Y1 3 59545MHz U2 Digital Output MT8870 Fig 4 DTMF decoder circuit It is a complete DTMF receiver with Low power consumption integrating both the bandsplit filter and digital decoder functions The bandsplit filter section separates the high and 2003 Vilnius DTMF signal controlled house monitoring system 13 low group tones It is followed by the digital counting section which verifies the frequency and duration of the received tones before passing the corresponding code to the output bus There is a minimum component count achieved by on chip provision of a differential input amplifier clock oscillator and latched three state bus interface OSC1 and OSC2 are corresponding clock input and output A 3 579545MHz crystal connected between pins OSC1 and OSC2 completes the internal oscillator circuit Connecting TOE pin Three State Data to high logic level it enables the outputs Q1 Q4 the pin is pulled up internally 01 04 when enabled by TOE provide the code corresponding to the last valid tone pair received StD pin presents logic high when a received tone pair has been registered and the output latch updated then it returns to low logic level The other information about DTMF decoder pins can be found at the Appendix D The steering circuit works in reverse to validate the interdigit pause between signals Thus as well as rejecting signal is too short to be considered valid the receiver will tolerat
3. File Edit View Help Dees loo Target Processor Ge 16F84 B Ral ode 2 A intbiink bas 2 potbas Includes DP ARR AAERRERREREEAERRERREERE AAAAEAAEAEEAERAREAEA A Defines By osc Name dtmfremote BAS J Constants Author arturas lukosius E Variables Notice Copyright c 2003 p All Rights Reserved x Date 25 04 03 S Version 1 0 i Notes DTMF controlled home monitoring system Yp m Ypk RRR EERRR KE EEEEEREEERRREEEERRR EERE EE EERIR EERIE EE EEIIR EE EERI Vy scale p out p des DEFINE OSC 4 oscillator 4MHz p vnt Alias and Modifiers 29 ringp variables BP mic B answer ringp var PortB 3 ring pin A aam mic var Porta 4 microphone E heat ansver var PortB 2 answer signal 2 temp alarm var Porti 3 alarm A secure heat var Porta 2 heating control temp var Porta 1 temperature sensor P snd secure var Porta 0 security check Ya snd var PortB 1 sound signal J Symbols var PortB t a PortB Labels p var Bit r ring var Byte index for gt main j var Byte index for loop m var Byte protection counter recognize k var Byte index for back scale var Byte scale for adjusting varying RC constants loop out var Byte output variable for temperature value gt heate des var Byte temperature every 100C gt temperature vnt var Byte temp every lol gt security gt res _ NJE 2 lt 2 ready Bini Co1 Erenn PSS SO Sh E RYS E Tota
4. information and security system This concept allows manipulating the house parameters heating system temperature and humidity monitoring common system access to Internet cable TV and radio information access between all the devices that can perform of course such an operation etc Of course this system allows different monitoring devices to be connected The user can hear what is going on in the house or found out the exact position of the noise source in the system Temperature monitoring can be also used for security improving We could speak about analogical systems but only in action simplicity The concept of Smart House is very expensive Sometimes the costs of installation of such a system is more than the total cost of the house used for it Touch screen LCD displays are often used inside the house for system interaction with user In such a case very complex soft for manipulating all the parameters of the house must be used thus resulting in increasing price The simpler version can be done if neglecting the usage comfortability we use simple PC to control the devices around us In this case some problems can occur because of the need to adopt the freeware soft to particular systems or to buy it separately In this case comfortability is decreased 2003 Vilnius DTMF signal controlled house monitoring system T Talking in general about the possibility of distant house control and monitoring we can consider 3 possibilities control
5. HMS through Internet mobile phone system is connected to mobile phone or simple telephone line In the last 2 cases we can use DTMF signal to manipulate the system parameters Each way has its advantages and disadvantages Advantages of the Internet connection case is reliability speed of operation almost no limitations in functionality of the system the limit is set up by the programmer only GUI allows for user to work in the comfortable OS etc This method is widely spreading even there are some specific disadvantages The main of them is comparably high cost Internet requires from system to be more complex use some standard hardware and software elements Also old or out of need PC can be used for this purpose But summing up system with some kind of PC legal operation system and Internet on line will results in quite high cost Also the user must ensure the access to Internet at the time he wants to check the system comparably high power consumption can be critical for some specific application where we need to ensure the proper system working even when power is off for some period and big dimension Also we can state that the reliability of the PC in such a system can be a critical factor hard disk working time limit There are systems that use connection of the mobile phone to inform the consumer about the motion vibration etc inside the room Because of very small dimensions these systems have very narrow specification can wor
6. bit 1 Resume Return to main program Enable T return from microphone monitoring to base menu Disable loopl m nm 1 after 1 min device hung up Pause 300 serout secure 4 m 13 10 If m 200 Then Low mic Low answer r hung up Goto ring EndIf If a 16 3 Then pressed PortB 00000011 Low mic 1 GFP mie Else GoTo loop1 repeat until EnDiF GoTO res T heat control We can press 3 to turn on or off heatc If heat 1 Then IE heat 18 on Etu urn 1C off heat 0 sound snd 0 15 107 35 GoTo back Else If heat 0 Then af heat is off tturn dt on heat 1 Sound snd 0 15 120 35 GoTo back return EndIf EndIf t temperature measurement Disable temperature scale 255 Pot temp scale out assign temperature variable value Pause 500 out out 2 65 normalized temperature 5 370C 2003 Vilnius DTMF signal controlled house monitoring system 29 des out 10 number of 100C vnt out des 10 number of 10C For j 1 To des Sound snd 107 30 0 15 beep for every 100C Next j For k 1 To vnt Sound snd 120 15 0 15 beep for every 10C Next k Serout secure 4 out 13 10 GoTo back T security checking security If secure 1 Then check if the secyrity system responsed For i 1 To 10 to alarm mode Pause 500 Sound snd 120 10 0 1 alarm alert Next i Else Pause 500 Sound snd 120 10 normal sound System i
7. capacitor C1 is required to stabilize the 78LO5 output current filter low distortions C5 4N35 5 5V Lnst DTMF Input gt HEADER 2 Electret microphone Fig 6 Auto riser and sound to line connection scheme The rectifier was placed in the circuit to rectify the voltage taken from the line The values of the resistors were taken to satisfy the condition of safe mode operation of the diodes The resistors R14 and R16 that are connected to the bases of the appropriate transistors Q2 and Q3 limit the current form the pins Mic and AnS of the PIC controller The transistor Q2 is working as the switch where the high output of AnS opens it that decreases the resistance between the line and ground to the value slightly bigger than R12 It results in the line to be raised up 2003 Vilnius DTMF signal controlled house monitoring system 15 Connection of the microphone is quiet simple and standard where through polarized capacitor is connected to transistor that amplifies the audio output to the line together with the signals caused by PIC controller In our case the microphone is powered form a SV power supply source through a resistor of 1 2kQ We have chosen the electret microphone because of its high durability low cost and low power consumption For all transistors in the given circuit we have used KT940A because of availability and high value of power that can be dissipated on it up to 1 2W The detailed characteristics o
8. house monitoring system based on PIC Microcontroller The device is connected to phone line and is controlled by DTMF signal emitted by DTMF encoder in stationary or mobile phones In presence of incoming call the device pick up the phone and answer the call connecting to the line User can press buttons and control the system remotely Function of keys should be known initially read manual in appendix B The functions are e speakerphone monitoring you can listen the sound in remote premise e room temperature monitor sound indication e output for heating switch we can turn on off the external heating e input for security check if it was alarmed the input must be high e alarm controller we can activate alarm system manually e automatic pick up raises after 4 seconds or could be changed 2003 Vilnius DTMF signal controlled house monitoring system 5 e automatic hung up if no buttons are pressed more than 1 minute it protects from accidental disconnection from the system for example out of radio coverage in mobile networks e monitoring indication is followed by sound signals read manual 2 2 Short Telephone Line Analysis Plain old telephone systems POTS telephone line consists of one wire pair which carries full duplex audio and the operating current for the telephone The telephone connected to line is powered from current limited 48V power source so phones on hook should measure around 48 volts DC P
9. phone line sockets available in every flat or house e Compatible with all phone line networks Telephone standards world is fragmented Typically each country has its own standards because of both the historical roots of the phone service and the desire to protect the local phone market from outside competition Basically the telephone systems work in the same way in different countries but there are some differences which can mean that devices designed for one country do not meet the regulations of other country and work poorly or not at all The differences in local technical standards range from minor to severe and affect many of the signaling conditions on local loops Surprisingly a telephone is one of the simplest devices we have in our house It is so simple because the telephone connection to our house has not changed in nearly a century Even 2003 Vilnius DTME signal controlled house monitoring system 4 in the case have an antigue phone from the 1920s you could connect it to the wall jack in your house and it would work fine The system is based on Microchip PIC Microcontroller PIC16F84 It employs the Flash memory which can be programmed up to 1000 times We use the PICBasic compiler Also we could write program using assembly language PASM but it could be used mainly for optimization of source program 2 Task Analysis 2 1 The purpose of the circuit Purpose of our course project is to develop DTMF signal controlled
10. turned off by the user The device can turn on alarm system In both cases external alarm and heating devices must be constructed according the function scheme of the PIC The simple temperature monitor system is connected to PIC Using different sound signal PIC can sound the user about the temperature Also there is a security watchdog that must inform situation with security system was it activated during the time user is away or not All the information about the peripheral devices is transformed to the form of the sound signals and then directed to the user 2003 Vilnius DTMF signal controlled house monitoring system 11 After the receiving signal to turn off PIC controller disables auto riser circuit Talking in general the amount of the output devices that can be controlled is limited by the number of available pins and memory that contains the operational program We can take more advanced controller for increased complexity system 4 Electrical Scheme 4 1 Electrical Scheme Analysis First we will consider the connection of the PIC controller to another elements of the circuit JP3 Digital Input Fig 2 PIC controller circuit There are 13 I O pins with individual direction control The program sets up the status of the pin Four pins from RB4 to RB7 are set to be digital input from the DTMF decoder Four of PORTB s pins RB7 RB4 have an interrupt on change feature Only pins configured as inputs 2003 Vilnius DTM
11. 4MHz T variables ringp var PortB 3 ring pin mic var PortA 4 microphone answer var PortB 2 answer signal alarm var PortA 3 alarm heat var PortA 2 heating control temp var PortA 1 temperature sensor secure var PortA 0 security check snd var PortB 1 r sound signal a var PortB a Ports p var Bit p L var Byte index for j var Byte index for m var Byte protection counter k var Byte index fote scale var Byte scale for adjusting varying RC constants out var Byte output variable for temperature value des var Byte temperatur very 100C vnt var Byte temp every 10C TrisB 11111001 set pin I O of PortB PortB 0 set value 0 to PortB TrisA 00000011 set pin I O of PortA PortA 0 set value 0 to PortB ring check t ring m 0 If ringp 1 Then check if ring appears Pause 4000 delay to answer for 5s High answer answer signal is on Pause 1000 Sound snd 122 6 0 3 123 6 0 3 124 6 0 3 125 6 0 3 126 6 0 3 125 6 0 3 _ 124 6 0 3 123 6 0 3 122 6 greeting sound train GoTo main execute recongnition Else GoTo ring repeat check till ring EndIf main program 2003 Vilnius DTMF signal controlled house monitoring system main On Interrupt GoTo recognize INTCON 90 loop idle Pause 300 accidental disconnections Serout secure 4 m 13 10 If m 200 Then option_reg 7 1 Low snd hung up Low answer Pause 5000 Goto ring EndIf GoTo loop recog
12. DTMF signal controlled house monitoring system 3 DTME Signal Controlled House Monitoring System HMS 1 Introduction Nowadays many people are looking for the methods to improve life conditions comfort and at the same time the simplicity of handling with domestic electric appliances Fewer skills are required bigger popularity and fewer problems even for not prepared user We can use PC for many purposes Among them there is a need to mention connection to Internet network using telephone line cable TV ADSL or radio modem make LANs WANs and different PC based monitoring and security systems But what is the proper decision for the system of domestic level The solution is to employ low complexity and low cost systems which is capable to perform certain functions designed and programmed under the requirements of the user This simple security system satisfies the main market conditions to be attractive for consumers The main advantages are mobility small size low power consumption low cost possibility to adopt system to new requirements by changing the main program Ability to connect the device to personal computer for data storage could be also available The device includes the standard and widely spread electrical elements thus implementing massive production Options that will attract people and companies to choose telephone line communication o Low price of installation and service e Simplicity of usage e Comfortability
13. F signal controlled house monitoring system 12 can cause this interrupt to occur i e any RB7 RB4 pin configured as an output is excluded from the interrupt on change comparison For a change on the I O pin to be recognized the pulse width must be at least Tcy 4 fosc wide In our case DTMF decoder sets up a constant digital output until the new signal appears The clock input from OSC1 is internally divided by four to generate four non overlapping quadrature clocks In general the PICI6F8X can be operated in four different oscillator modes We use XT mode Crystal Resonator In this mode a crystal or ceramic resonator is connected to the OSC1 CLKIN and OSC2 CLKOUT pins to establish the oscillation c10 c21 PIC16FXX Fig 3 General form of connection of oscillator Recommended capacitor selection for the oscillator is 15 33pF for both C1 and C2 in the case of frequency 4MHz Higher capacitance increases the stability of oscillator but also increases the start up time Rs may be required at our mode to avoid overdriving crystals with low drive level specification but in our case we can use the oscillator without it Pins RB1 RB2 and RB3 are used as outputs for PIC sound signals answering function and as input for line status determination They are internal software programmable weak pull up IVO pins MCLR is master clear reset input programming voltage input This pin is an active low reset to the device Ci 0 1uF
14. Temperature oC Fig 8 Graphical representation of temperature dependent variable OUT Considering the security check and alarm we can see that because of the diode and resistance to be connected in series we have that voltage drop on the LED is approximately V 0 7V then the resultant voltage on the resistance is as V E V 5 0 7 4 3 V Finally the current flowing can be found approximately be 9 Him Then the R 390 power dissipated on resistors can be found as P 1 R 390 0 011 0 047 W on each resistor Because of the same current flowing in diodes and resistors we can measure also the power dissipated at the diodes as P UI 0 7 0 011 7 7x10 W Applying to the datasheets of the diodes we see that the flowing current is almost twice less than maximum allowed thus we can omit this calculations in the future because of the similar resistances in series in all the other places and amplitude of the acting voltage not bigger 5V Considering DTMF we see that the maximum allowed DC power supply voltage is up to 7V thus our value of SV satisfies the requirements The range on any pin is in the range from 0 3 to 5 3V calculating as of supply voltage with variation of 0 3V in upper directions and ground to lower one This value we will assume to be the highest possible when considering maximum power dissipation min V V 0 3 V max V V 0 3 V The maximum allowed current at any pin could be up to 10mA except
15. are caused not by the certain device but by the principle of 2003 Vilnius DTMF signal controlled house monitoring system 8 operation based on sound where the information representation isn t as obvious as in the GUI systems In the following chapters we will try to analyze the principles of operation of such a device the algorithm of working and some internal calculation 2 4 Schematic Production In the process of schematic production we have tried to use as more similar elements as possible As the source of the control the PIC16F84 was used It allows rewriting the internal program thus experiments can be performed without any damage For this purpose there is 1Kb of Flash memory for program code In the case of massive production after the development of such a system there can be used PIC microcontrollers with not rewritable memory PIC16CR8X having the same structure The microcontrollers produced by Microchip are comparably old thus their functional abilities were tested by the time There is a huge amount of software for programmers available that result in simplicity of programming Additionally to the device the programmer was created For the decoding of the DTMF signals external hardware DTMF decoder was used Of course there was a possibility to make DTMF decoder by program inside the PIC but then the functionality would be less because of small program memory For the detailed information about the parameters and cha
16. e signal interruptions dropout too short to be considered a valid pause The functional decode table can be found below The table represents the information about the status of the pins corresponding to certain input signal of the decoder We have single end configuration thus the op amp is connected for unity gain and V biasing an input at Vp All information about the principles of operation of the DTMF decoder can be found at Appendix D o N p m Y O ae S ae SE n ojojojlojojoj ojlN z i E aa 1 2 H 3 H 4 H H H H H H H H H H H H H H H o ojoj N ajla e mel o c pea od o A Me mA e cd JE E Ce ee ee 9 9 9 o ojl N oOj o ma oy mf Oy am Oy oj Oy oj mK N s E S Sk 38 E AE undetected the output code a Will remain thassamer as the Table 2 Functional Decode Table previous detected code L logic low H logic high Z high impedance X don t care OO DO gt ojojoj gt en SS OS OS OSS S SS 1S DC I OS Tse a Ss GE eae U 2003 Vilnius DTMF signal controlled house monitoring system 14 Below the simplest circuit of the programmer will be considered 1N4148 Fig 5 PIC Programmer circuit CONNECTOR DB9 This circuit was used to program the PIC 16F84 controller The resistances are placed for current limitation The
17. f the amplifiers and LED can be found additionally at Appendix E The transistor O1 is acting as amplifier sending the sound to the line If not making too high requirements to the sound quality it is enough to inform the user about the situation The phototransistors optocoupler is used to separate the line status input of the controller from DC voltage in the line For this purpose the capacitor is present in series with diode circuit of the optocoupler In this case only AC voltage appears that is a signal of ringing up The diode opens the transistor and there is a high voltage level at the line status input causing the controller to turn on auto rise circuit The resistor in series and diode must guarantee the proper operation of the circuit S1 s 1 3 P o o a JE x Sk Ri JP1 U1 2k 5V 78L05 adh 100nF 4 9 and DC Supply RO it VDI 330uF TH TRANSFORMER W n u LED Y O io TN gt gt Sa Fig 7 The circuit of the power supply The circuit of the power supply is quite simple Standard 78L05 positive voltage regulator for SV output voltage is placed The capacitors are used in order to decrease the possible voltage oscillations 2003 Vilnius DTMF signal controlled house monitoring system 16 HEADER 2 Electret microphone MICROPHONE b Fig 8 LED indicators a external connecto
18. gorithms Crosstalk from other conversations is another form of noise To ring the telephone the telephone company momentarily applies a 90 V RMS 20 Hz AC signal to the line Even with a thousand ohms of line resistance this is still a bit of a shock The ring signal is much the same worldwide It is around 90V at a frequency between 16 2 3 Hz and 50Hz 20 25 Hz quite common But its timings are wildly different as are the return tones it generates 2003 Vilnius DTMF signal controlled house monitoring system 6 While digital telephone lines are quickly coming to the telecom field it seems that analogue telephone lines are still here to stay for a long time Strangely enough fax machines and modems will keep analog lines available even in buildings with ISDN and digital PBXs To ensure the proper functioning of the device we can set certain limits in operating regimes of the device This is caused by the obvious simplicity of the circuit There are no elements ensuring constant output or operation principles in the wide range of line parameters In the case the circuit is not working properly we must check rather it satisfies the following requirements Stand by Talk Ring Table 1 Requirements for telephone line 2 3 Analogical Circuits Worldwide The popularity of Smart House concept is rapidly increasing in the most developed countries In general this system includes domestic electric appliances networking and united
19. k only with certain mobile phone because are adopted to certain version of software use mobile phone number Because of very small dimensions they are quite expensive that exceeds their functional value Among the advantages we could mention their mobility and low power consumption Usually they can use the battery of the mobile phone as the source of the energy for a certain time but for a longer period constant power supply must be found There is almost no possibility to improve their characteristics or functionality At last there is a need to mention the telephone line based system It is a cheap single task system that performs the operations you need Internet free control and small power requirements comparing with complex one based on PC There is also a possibility to reprogram the system in the certain range changing the periods of task performing enabling or disabling some initially programmed functions setting up the password etc The main disadvantage is a subscriber number possible phone line distortions and limits of available functions in general this disadvantages can be of mobile phone based systems also no graphical and sometimes vocal implementation it requires form the user to have some initial knowledge about control System protection from unauthorized access is a common problem for the both cases Some of the problems can be solved using more advanced microcontroller for the device but in general the disadvantages
20. l command E microsoft Visio gx RA Document Mis p NGAR REE Address http www bellsouth net Eo mO 6 21 2003 5 2 Program algorithm 2003 Vilnius DTMF signal controlled house monitoring system 2003 Vilnius 21 DTMF signal controlled house monitoring system START The ring is resent No p Pick up the phone AA Pause 1s y Greeting Sound Go to MAIN 2003 Vilnius Interrupt signal it checks after each command p m m 1 tM Pause 300ms Close PIC sound transistor y Hung up Go to RING Go to LOOP DTMF signal controlled house monitoring system Recognize e y Disable Interupts Turn on microphone m 0 Go to LOOP1 GO to TEMPERATURE Go To HEATC Go to SECURITY Turn on alarm signal Vv Pause 1s AA Leaving sound v train Sound train indication AA Pause 1 5s T U i Go to BACK See rier v g Hang up Go to BACK AA Pause 5s Go to RING 2003 Vilnius Enable Interupts Go to MAIN ore y m m 1 y Pause 300ms y Turn off microphone y Hung up Go To RES 23 Pressed Turn off microphone Go to LOOP1 DTMF signal controlled h
21. nition of DTMF number Disable recognize F 1 microphone monitoring T If a 16 8 Then High mic m 0 GoTo loopl appears below EndIf F 2 temperature monitor T If a 16 4 Then GoTo temperature EndIf T rong Reat control ih If a 16 12 Then GoTo heatc EndIf i 4 security check If a 16 2 Then Goto security EnDiF t PONS alarm Concerod If a 16 10 Then High alarm Pause 1000 Sound snd 120 50 Low alarm GoTO back EnDiF 2003 Vilnius 21 Define interrupt handler Enable INTE interrupt counts m until 200 if system is mainly to protect from turn Off pull up of partb low snd pin to avoid errors with hung up No interrupts past this point 1 pressed PortB 00001000 turn on mic reset m counter jump to subroutine loopli 2 pressed PortB 00000100 temperature monitor 3 pressed PortB 00001100 heat control 4 pressed PortB 00000010 security check 5 pressed PortB 00001010 send Is pulse to alarm circuit DTMF signal controlled house monitoring system 28 F NAN Sa hang up If a 16 13 Then pressed PortB 00001011 Sound snd 0 50 126 6 0 3 125 6 0 3 124 6 0 3 123 6 0 3 122 6 option_reg 7 1 Pause 1500 Low answer hung up Pause 5000 Goto ring go to wait for ring state Else GoTo back EnDiF back m 0 INTCON 1 0 Enable interupt register
22. o program Microchip Technology s powerful PICmicro microcontrollers MCUs The English like BASIC language is much easier to read and write than the quirky Microchip assembly language The PicBasic Pro Compiler is BASIC Stamp II like and has most of the libraries and functions of both the BASIC Stamp I and II Being a true compiler programs execute much faster and may be longer than their Stamp equivalents PBP is not quite as compatible with the BASIC Stamps as our original PicBasic Compiler is with the BS1 Decisions were made that we hope improve the language overall One of these was to add a real IF THEN ELSE ENDIF instead of the IF THEN GOTO of the Stamps These differences are spelled out later in this manual PBP defaults to create files that run on a PIC16F84 04 P clocked at 4MHz Only a minimum of other parts are necessary 2 22pf capacitors for the 4MHz crystal a 4 7K pull up resistor tied to the MCLR pin and a suitable 5 volt power supply Many PICmicro MCUs other than the 16F84 as well as oscillators of frequencies other than 4MHz may be used with the PicBasic Pro Compiler The PicBasic Pro Compiler produces code that may be programmed into a wide variety of PICmicro microcontrollers having from 8 to 84 pins and various on chip features including A D converters hardware timers and serial ports 2003 Vilnius DTMF signal controlled house monitoring system 20 The current version of the PicBasic Pro Compiler sup
23. ombination that can be uniquely recognized by the controller and will cause certain operation to be performed There is no specific requirements for the DTMF decoder because in the interested level they are general the same According the obtained digital signal controller set up some output to high or low level depending on program Of course there is always possibility to use simple logic for such a simple operation but the resulting problem will be obtained Even small amount of logic circuits with certain fixed operation will require several different logic circuits and more place on the board The resultant circuit becomes more complex and possibility of mistake in design and production also increasing Using circuits of the fixed logic we can t reprogram the device even in a small range For some cases it will decrease the reliability of the system and possibly increase the power consumption Heating control by the definition must remain on off even when the interaction between user and system is finished The output to alarm control is done with the assumption that external device will be capable to turn on off by the given pulse Also the construction of the external microphone can be improved in order to increase the sensitivity by adding high quality amplifier 2003 Vilnius DTMF signal controlled house monitoring system 10
24. ouse monitoring system TEMPERATURE AA Disable interupts AA SACLE 255 Measure time constant and assign variable OUT AA Pause 500ms AA OUT OUT 2 65 v DES OUT 10 v VNT OUT DES 10 y Sound to line y J J i 2003 Vilnius RES Pause 1s Go to MAIN AA Sound to line y K K i Go to BACK SECURITY l 10 v Pause 500ms v Alaert sound signal to line HEATC Sound beep to line Low Normal one beep to line BACK ae GO to BACK eae Sound beep to line High GO to BACK 24 DTMF signal controlled house monitoring system Appendix A PICBasic Program 2003 Vilnius 25 DTMF signal controlled house monitoring system 26 DKK KKKKKKKKKKEKKKKKKAKKKKKKKKKKKKKKKKKKKKEKKKEKKKAKKKKKKKKKKKKKKKKKKAE Name dtmfremote BAS Author arturas Jukosius rx Notice Copyright 2003 du All Rights Reserved m Date z 25 04 03 Version i 1 0 i Notes DTMF controlled home monitoring system Fe PAKA KA KA AA kk kr teke ker ke ke skr te ie ke eko ke ke te ie ee ke ke ke ke ker ke este eter kese ste ie ke ee A AA AA LAKA DEFINE OSC 4 oscillator
25. ports all the Microchip Technology PICmicro MCUs including the 12 bit core 14 bit core and both 16 bit core series the 17Cxxx and 18Cxxx devices as well as the Micromint PicStics Limited support has been added for PICmicro MCUs based on the original 12 bit core Support is limited as the 12 bit core PICmicro MCUs have a limited set of resources including a smaller stack and smaller code page size We can see that our program has a complex structure of various functions cycles condition relations delays etc It works without end that means that when we power on the microcontroller sets in the MAIN loop In online regime it counts the variable M until 200 unless the interrupt from DTMF decoder is sent this set M 0 At the moment when M 200 the device hung up and go to wait for ring state in RING program cycle The number pressed on remote phone is characterized by RECOGNIZE cycle The essence of working is reading 4 bit signal from DTMF decoder output when interrupt signal is activated PIC controller after current program jumps to RECOGNIZE cycle and performs recognition of 4 bit code relating with initial values If code if recognized program jumps to the certain cycle and performs it Later it goes to wait for interrupt state To protect occurrence of error due to accidental disconnections after device hung up automatically in one minute Ke MicroCode Studio PICBasic Pro intblink bas BAX
26. r circuit b The working principle of these circuits is quite simple The operation of the temperature monitor is based on the assumption that in the certain range resistance of the thermistor changes linearly allowing us to make calculations of the temperature The switch in the security check circuit plays the role of the separate distant security system to be activated or not In the case of the security system to be activated the switch is modeled as closed causing high input voltage at Sec pin Alarm pin directly turn off on alarm system connected to it The LEDs and appropriate resistances are placed only for making operation obvious and in general case can be omitted 4 2 Investigation of the Electrical Scheme The investigation of the circuit we will begin with analyzing the thermistor The following table and graphs represent experimentally obtained values of the discrete PIC determined values Table 2 Investigation of out variable dependence on temperature Temperature OUT variable levels 48 00 29 00 43 00 34 00 38 00 39 00 32 00 46 00 26 00 56 00 24 00 62 00 23 00 66 00 16 00 81 00 14 00 84 00 12 00 89 00 9 00 92 00 6 00 109 00 2003 Vilnius DTMF signal controlled house monitoring system 17 Investigation of thermistor 140 120 100 80 60 40 Integer values of microcontroller variab 20 0 10 20 30 40 50
27. racteristics features of the PIC and DTMF decoder look Appendix C and D Also the power source for 5V were done and inserted as the part of the system It was done internal because of the system to be more stable and reliable For all the other circuit parts the standard and quite cheap elements were used As the indication of the device functioning LED were used at several outputs as indicators In general here is no need of them for proper device operation but the purpose was to make the device more friendly and obvious functioning principles In order to increase the volume of memory some external chips with I2C interface can be used optionally for future circuits with larger amounts of sound The circuits for auto rising and sound to the telephone line are similar to those that are used in stationary telephones with ability to determine calling number For the particular explanation of the circuit elements and entire calculations look for the chapter 4 2003 Vilnius DTMF signal controlled house monitoring system 9 3 Structural Functional Scheme 3 1 Creation of the Structural Functional Scheme As the main controlling device we have chosen the PIC controller in general any other controller with similar functionality and memory volume can be used As the device that forms digital input DTMF decoder was chosen It has to form unique digital combination that will be accepted by the PIC controller For each DTMF signal there is a c
28. ractically the operating voltages of telephone systems can vary from 24V to 60V depending on the application although 48V nominal voltage is the most commonly used When telephone is put off hook the voltage between wires going to telephone drops down to the 3 to 9 volt range and typically a current of 20 60 mA will flow through the telephone The typical operating current range is 20 35 mA Any more than 55 or 60 mA and it might harm the phones So the telephone equipment itself does not need any high voltages to operate The remaining voltage drop from 48V to 3 9 volts occurs over the copper wire path and in the telephone central electronics This high voltage is needed in the beginning because the length of the telephone line can be many kilometers which means lots of wire resistance on the way to drop the voltage Typical telephone DC resistance around 180 ohms and AC impedance is typically somewhere around 600 ohms Typically the telephone central provide from 200 to 400 ohms of series resistance to protect from short circuits and decouple the audio signals The typical signal to noise ratio of a telephone line is approximately 45 dB or somewhat less Telephone line signal to noise ratio is not as easy to quantify because noise comes in many forms such as electrical interference from fluorescent fixtures or hiss from the many amplifier stages in the voice path Speech correlated noise can be introduced from non linear speech coding and compression al
29. s idle EndIf GoTo back i res m 0 Pause 1000 Resume return to main program Enable enable global interrupt Appendix B Device User Manual Appendix C PICI6F84A Data Sheets 2003 Vilnius DTMF signal controlled house monitoring system 30 Appendix D Integrated DTMF Decoder Appendix E LM78LXX Series 3 Terminal Positive Regulators Appendix E Discrete Elements Datasheets 2003 Vilnius
30. the supply one 2003 Vilnius DTME signal controlled house monitoring system 18 At the input of the DTMF decoder there is resistance of 100kQ Assuming that the maximum input voltage can be up 55V only DC component and 72V DC AC when ring It is obvious that for both cases the resistances of 100kQ and 390kQ together with very big input impedance approximately 1OMQ input resistance of the decoder allow us to reach the safe very small current value The maximum power dissipation of the package is 5 00mW Thus the power consumed by the circuit must be less than the maximum possible power dissipation The decoder consumes approximately 3 4mA DC supply current It results in the typical power consumption as P UI 3 4 x10 x5 15 20 mW with the given oscillator For all the pins used as outputs the high level is approximately 4 5V Very small currents at these pins ensures the total power consumption of the chip is almost equal to that calculated above We will try to investigate the basic steering circuit Before the registration of a decoded tone pair the receiver checks for a valid signal duration referred to as character recognition condition This check is performed by an external RC time constant driven by Est A logic high on ESt causes ve to rise as the Si capacitor discharges Provided signal condition is aran ROR l ee l MT8870D 1 maintained Est remains high for the validation period torp Vc reaches
31. the threshold Vys of the steering Fig Basic steering circuit logic to register the tone pair latching its corresponding 4 bit code into the output latch At his point the GT output is activated and drives ve to Vj GT continues to drive high as long as Est remains high Finally after a short delay to allow the output latch to settle the delayed steering output flag StD goes high signaling that a received tone pair has been registered The output voltage of LM78L05 is form 4 8V to 5 2V depending on the load There is an internal thermal overload protection and internal thermal regulation The output current can reach the maximum value of 140mA that is enough for our circuit Maximum PIC microcontroller power dissipation is approximately 800mW It is logic device based on logic level voltages All logic level currents are small hundreds of 2003 Vilnius DTMF signal controlled house monitoring system 19 microampere range All the parameters maximum and minimum conditions can be found in appendix C Transistors KT940A is most popular in phone line circuits because of their parameters suitable for such case They can be found in appendix E 5 Programming software and algorithm 5 1 Software The program was written with Microcode Studio using PicBasic Pro Compiler It is placed in appendix A The PicBasic Pro Compiler or PBP is our next generation programming language that makes it even quicker and easier for you t
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