Working with two sensors is similar to working with just one. One should alternate the code for the first and the second sensor. It is important to make sure that only one LED emits in a time. This is necessary to avoid the IR receiver modules to catch signals from a wrong LED. In this experiments we practically double the schematic for the previous experiment and the corresponding code: use 2 IR receiver moduls, 2 IR emitting LEDs, and 2 (visible) red light LEDs for indication (one of them is not shown on the schematic and must be attached via a 470 Ohm current-limiting resistor to the hanging pin RC3 of PIC).
| Schematic |
The code is as follows:
TITLE "ir2.asm" ; working with two IR sensors List P=PIC16F684, R=DEC INCLUDE "p16f684.inc" ; data segment CBLOCK 0x20 del ; variable used for delay pulse, pulses2Send, pulsesReceived ENDC ; code segment PAGE __CONFIG _FCMEN_OFF & _IESO_OFF & _BOD_OFF & _CPD_OFF & _CP_OFF & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTRC_OSC_NOCLKOUT org 0 ; start program at the beginning of mem bcf STATUS, RP0 ; activate BANK 0 clrf PORTC ; initialize PORT C movlw 0x07 movwf CMCON0 ; comparators OFF bsf STATUS, RP0 ; change to BANK 1 clrf ANSEL ^ 0x80 ; make all inputs digital movlw b'101101' movwf TRISA ^ 0x80 ; enable RA1 and RA4 for output bcf TRISC ^ 0x80, 2 ; enable RC2 for output bcf TRISC ^ 0x80, 3 ; enable RC3 for output bcf STATUS, RP0 ; back to BANK 0 clrf pulse ; start with IR pulse value 0 loop movlw 10 movwf del call delay ; 10 msec delay ; process pulses from the right sensor clrf pulsesReceived movlw 20 movwf pulses2Send send_pulses1 goto $+1 goto $+1 btfss PORTA, 0 ; is there IR reflected waveform? incf pulsesReceived, f movlw b'10' xorwf pulse, w ; compose a new pulse value movwf pulse movwf PORTA ; output the new pulse value decfsz pulses2Send, f goto send_pulses1 ; end of a 26 cycle (38KHz=26.3mksec) movlw 4 subwf pulsesReceived, w ; C=1 if more than 2 pulses received movf PORTC, w andlw b'11111011' btfsc STATUS, C iorlw b'100' ; turn on LED movwf PORTC ; process pulses from the left sensor clrf pulsesReceived movlw 20 movwf pulses2Send send_pulses2 goto $+1 goto $+1 btfss PORTA, 5 ; is there IR reflected waveform? incf pulsesReceived, f movlw b'10000' xorwf pulse, w ; compose a new pulse value movwf pulse movwf PORTA ; output the new pulse value decfsz pulses2Send, f goto send_pulses2 ; end of a 26 cycle (38KHz=26.3mksec) movlw 4 subwf pulsesReceived, w ; C=1 if more than 2 pulses received movf PORTC, w andlw b'11110111' btfsc STATUS, C iorlw b'1000' ; turn on LED movwf PORTC goto loop ; endless loop ; procedures delay ; a delay for del milliseconds movlw 200 sublw 1 ; this loop takes 5us*200 = 1ms sublw 0 ; for PIC16F684 @ 4 Mhz btfss STATUS, Z goto $-3 decfsz del, f goto delay return end |
Download ir2.asm
Last modified:Mon, Jan 23, 2023.