PIC Microcontroller Based Wireless Temperature and Heart Beat Read-Out

Transcription

1 PIC Microcontroller Based Wireless Temperature and Heart Beat Read-Out EM TESTED EM TESTED EM TESTED MUDIT AGARWAL Microcontroller Based Wireless Temperature And HeartBeat Read Out suitable for operation in a small office/home environment. This system is easy to operate, with Visual LCD. Many individuals and organizations may, for various reasons, wish to use electronic surveillance techniques at some time or another. The idea is to use off-the-shelf RF Tx/Rx modules. The weather keeps us continually occupied. Some people have even made it their profession. At home too, we like to measure all kinds of things related to our climate. That is why weather stations are available in all types and sizes. If we want to know the temperature inside and outside then purpose-built indoor/outdoor thermometers are available. In the past the outside sensor of these weather stations was connected with a wire, it is now fairly standard to use RF transmission for this data. This Wireless transmitters units usually make use of the 5-MHz band. These modules, once a rare commodity, are now widely and cheaply available. In this particular discussion, we shall be using ASK (Amplitude Shift Keying) based TX/RX pair operating at 5 MHz. The transmitter module accepts serial data at a maximum of 400bps. They are directly interfaced to a microcontroller. At the RX end, the receiver microcontroller receives the signal via the RF receiver module, decodes the serial data and reproduces the original data in the temperature and Heat Beat format. Temperature Sensors Temperature is one of the fundamental physical variables in most chemical and process control applications. Accurate and reliable measurement of the temperature is important in nearly all process control applications. Temperature sensors can be analog or digital. Some of the most commonly used analog temperature sensors are: thermocouples, resistance temperature detectors (RTDs) and thermistors. Digital sensors are in the form of integrated circuits. The choice of a sensor depends on the accuracy, the temperature range, speed of response, thermal coupling, the environment (chemical, electrical, or physical) and the cost. A popular voltage output analog integrated circuit temperature sensor is the LM5DZ, manufactured by National Semiconductor. This is a -pin analog output sensor which provides a linear output 0 voltage of 0 mv/ C. The temperature range is C to 00 C, with an accuracy of ±.5 C. Hear Beat Siganlling The Heart Beat signal is obtained by LED and LDR combination. Pulses form hands interrupts the Light reaching the LDR and this signal is read by microcontroller, Temperature Sensor Micocontroller & RF Receiver with LCD Micocontroller & RF Transmitter With LCD Heart Beat Assembly Fig.. Block Diagram of PIC Microcontroller Based WirelessTemperature and Heart Beat Read-Out

2 5V LED R LDR R C7 Ic Pr R4 A l o g i c a l z e r o i s represented by a pulse in the first half of the bit time. A logical one is represented by a pulse in the second half of the bit time En 6 D7 D6 D5 D4 D D D D V A.C X 5V R R/W RS 5 4 V Transformer D D C C C The RF signal is transmitted by transmitter in a digital format. This circuit uses manchester encoding to avoid a long trail of one or zero. The protocol is well defined for different device types ensuring compatibility with your whole entertainment system 5 bit address and 6 bit command length. Constant bit time of.778ms bits are of equal length of.778ms in this protocol, C5 Ic N4007 D D4 7 C6 5 LCD Ic VLC VCC VSS VC 6 Pr Ic 6 5 VA 5 V DC Fig.. Transmitter Circuit Diagram of PIC Microcontroller Based Wireless Temperature and Heart Beat Read-Out 4 R5 5V R9 P I C M i c r o - controller Microcontrollers contain all the components required for a processor system in one chip, a CPU, memory and I/O. A complete system can therefore be built using one MCU chip and a few I/O devices such as a keypad, display and other interfacing circuits. Most of the pins are for input and output, and arranged as 5 ports: PORTA(5 pins),port B(8 pins), PORTC(8 pins), PORTD(8 pins) and PORTE( pins), giving a total of I/O pins. These can all operate as simple digital I/O pins, but most have more than one function, a n d t h e m o d e o f operation of each is selected by initializing various control registers within the chip. Port B is used for downloading the program to the chip flash ROM and RB0 and RB4 RB7 can generate an interrupt. Port C gives access to timers, while Port D can be used as a slave port, with Port E providing the control pins for this function. Software RFTX 4 R6 list P=6F877A #include <P6F877A.INC> config _WDT_OFF & _XT_OSC & _CP_ON & _CPD_ON & _BODEN_OFF & _MCLRE_OFF & _PWRTE_ON

3 0V A.C. En 6 Transformer R/W RS 5 4 D7 D6 D5 D4 D D D D #DEFINE CHRC,0 #DEFINE CHRC, #DEFINE CHRA,0 #DEFINE TOG_BIT TOGGLE,0 #DEFINE CH_CMD0X0 #DEFINE CH_CMD0X0 #DEFINE CH_CMD0X0 CNTEQU0H CNTEQUH CNTEQUH CNT4EQUH TOGGLEEQU4H X 5V R D D N4007 C5 D Ic D4 C6 6X LCD C C C VLC VCC VSS VC Pr GOTO MAIN LOGIC0: MOVLW. MOVWFCNT LOG0_: BSFDATA BCFDATA GOTOLOG0_ CALLDELAY_OFF 5 V DC Fig.. Receiver Circuit Diagram of PIC Microcontroller Based Wireless Temperature and Heart Beat Read-Out Ic 4 RFRX VA 5V CMDEQU5H ORG000 BCFDATA BSFSTATUS,RP0 CALL0XFF MOVWFOSCCAL BCFSTATUS,RP0 BCFSTATUS,RP0 BCFINTCON,GIE BCFTOG_BIT MAIN:SLEEP BTFSSCH GOTODO_CH BTFSSCH GOTODO_CH BTFSSCH GOTODO_CH DO_CH: BTFSCCH M O V L W CH_CMD MOVWF CMD CALLSEND_RF BTFSSCH DO_CH: BTFSCCH M O V L W CH_CMD MOVWFCMD CALLSEND_RF BTFSSCH ; DO_CH: BTFSCCH M O V L W CH_CMD MOVWFCMD CALLSEND_RF BTFSSCH

4 LOGIC: CALLDELAY_OFF MOVLW. MOVWFCNT LOG_: BSFDATA GOTO$ BCFDATA DECFSZCNT,F GOTOLOG_ DELAY_OFF: MOVLW5 MOVWFCNTMOVLW.54MOVWFCNT4DECFSZC N T 4, F DECFSZCNT,F GOTO$-5 SEND_RF: CALLLOGIC CALLLOGIC BTFSSTOG_BIT GOTO$ CALLLOGIC GOTO$ CALLLOGIC CALLLOGIC0 CALLLOGIC CALLLOGIC RLFCMD,F RLFCMD,F MOVLW6 MOVWFCNT RLFCMD,F COMPONENT LIST (Transmitter) SEMICONDUCTOR DEVICE Ic 7805 Ic Lm5 Ic PIC6F877A Ic4 Lm58 D-D4 N4007 LED Red LED CAPACITORS C C,C,,C7 C5,C6 000 uf/5v 0.uf pf RESISTORS R,R 0K R.K R4 00K R5 47K R6 K Pr k Preset MISCELLANEOUS X 6X LCD VTtransformer LDR RF Transmitter 4MHZ Crystal Push To ON Switch SEMICONDUCTOR DEVICE Ic 7805 Ic PIC6F877A D-D4 N4007 CAPACITORS C C,C, C5,C6 RESISTORS R Pr COMPONENT LIST(Receiver) BTFSSSTATUS,C GOTO$ CALLLOGIC GOTO$ CALLLOGIC0 DECFSZCNT,F GOTO$-7 RETLW0; DEBOUNCE: MOVLW. MOVWF CNT DEL_: MOVLW.0 MOVWF CNT DEL_: CLRF CNT DEL_: DECFSZ CNT,F GOTO DEL_ DECFSZ CNT,F GOTO DEL_ end 000 uf/5v 0.uf pf 0K k Preset MISCELLANEOUS X 4MHZ Crystal Push To ON Switch 6X LCD VTtransformer RF Receiver Module Receiver Code list P=6F877A #include <P6F877A.INC> config _WDT_OFF & _XT_OSC & _CP_ON & _CPD_OFF & _BODEN_OFF & _MCLRE_OFF & _PWRTE_ON #DEFINE OUTRA, #DEFINE OUT_M0x0 #DEFINE TOG_BIT TOGGLE,0 #DEFINE ADDRS 0X0B #DEFINE CH_CMD0X0 #DEFINE CH_CMD0X0 #DEFINE CH_CMD0X0 #DEFINE CH4_CMD0X04 #DEFINE CH5_CMD0X05 #DEFINE CH6_CMD0X06 #DEFINE CH7_CMD0X07 #DEFINE CH8_CMD0X08 #DEFINE CH9_CMD0X09 #DEFINE CH0_CMD0X0A

5 Transformer Pr R Ic R J J J J4 J5 LCD J6 J7J8 Ic J9 X R Ic4 J0 C5 C6 GND RFTX R4 R5 R6 LED D D D D4 C C IC C LDR C7 Pr Fig.4. Transmitter Componenet Layout of PIC Microcontroller Based Wireless Temperature and Heart Beat Read-Out. CNTEQU0H CNTEQUH CNTEQUH CNT4EQUH TEMPEQU4H TOGGLEEQU5H Fig.5. Transmitter PCB Layout of PIC Microcontroller Based Wireless Temperature and Heart Beat Read-Out.

6 D D4 C C IC Transformer C D D ADDREQU6H CMDEQU7H ORG000 BSFSTATUS,RP0 BSFSTATUS,RP0 RFRX C5 C6 X Ic Fig.6. Receiver Component Layout of PIC Microcontroller Based Wireless Temperature and Heart Beat Read-Out R J6 J7J8 LCD DO_CH4: MOVLW OUT4_M Fig.7. Receiver PCB Layout of PIC Microcontroller Based WirelessTemperature and Heart Beat Read-Out J J J4 J5 MOVLW0X0 M O V W F OPTION_REG MOVLWB' ' MOVWFTRISIO CLRFIOCB BCFSTATUS,RP0 BCFINTCON,GIE MAIN: CALLDELAY500 CALLGET_RF BTFSCSTATUS,C MOVFADDR,W XORLW ADDRS BTFSSSTATUS,Z MOVFCMD,W ANDLW0X0 ADDWF PCL,F GOTODO_CH DO_CH: Pr MOVLW OUT_M DO_CH: MOVLW OUT_M DO_CH: MOVLW OUT_M J DO_CH5: MOVLW OUT5_M DO_CH6: MOVLW OUT6_M DO_CH7: MOVLW OUT7_M DO_CH8: MOVLW OUT8_M DO_CH9: MOVLW OUT9_M DO_CH0: MOVLW OUT0_M CHANGE: GET_RF: GOTOGET_RFC L R F TMR0 BCFINTCON,T0IF BTFSCINTCON,T0IF GOTOERR

7 GOTO$- MOVFTMR0,WMOVLW 0xC8 MOVWF TEMP MOVLW 0XFF SUBWF TEMP,W BTFSCSTATUS,C GOTOERR MOVLW 0XC8 SUBWF TEMP,W BTFSSSTATUS,C GOTOERR CALLDELAY5 BCFTOGGLE,7 BSFTOGGLE,7; GOTO$4 GOTOREAD; READ: MOVLW5 MOVWFTEMP CLRFADDR READ: CALLDELAY5 BSFSTATUS,C RLFADDR,F; GOTO$4 GOTO$ DECFSZTEMP,F GOTOREAD MOVLW6 MOVWFTEMP CLRFCMD CMD: CALLDELAY5 BSFSTATUS,C RLFCMD,F; GOTO$4 GOTO$ DECFSZTEMP,F GOTOCMD CONSTRUCTION MOVLW0XF ANDWFCMD,F MOVLW0XF ANDWFADDR,F ERR:BSFSTATUS,C DEBOUNCE: MOVLW. MOVWFCNT DEL_: MOVLW.0 MOVWFCNT DEL_: CLRFCNT DEL_: DECFSZCNT,F GOTODEL_ DECFSZCNT,F GOTODEL_ DECFSZCNT,F GOTODEL_ RETLW0 DELAY5: MOVLW. MOVWFCNT REP_: MOVLW.5 MOVWFCNT REP_: MOVLW.8 MOVWFCNT REP_: DECFSZCNT,F GOTOREP_ DECFSZCNT,F GOTOREP_ DECFSZCNT,F GOTOREP_ GOTO$ GOTO$ GOTO$ GOTO$ DELAY500: MOVLW. MOVWFCNT MOVLW. MOVWFCNT MOVLW.50 MOVWFCNT DECFSZCNT,F DECFSZCNT,F GOTO$-5 DECFSZCNT,F GOTO$-9 RETLW0 END FINISHED