;********************************************************************** ; * ; Filename: Decoder2.asm * ; Date: * ; File Version: * ; * ; Author: Ian Harding * ; Company: (c) Electric Images, 2009 * ; Permission is given for personal use only * ; * ;********************************************************************** ; * ; Files required: P12F629.INC * ; * ; * ; * ;********************************************************************** ; * ; Notes: * ; Uses internal oscilator - should be 4MHz * ; * ; GP0: Serialised data out (ICSPclk) * ; GP1: Confidence out to LED to gnd (ICSPdata) * ; GP2: IR Detector 1 in, hi on active * ; GP3: (MClr) * ; GP4: * ; GP5: * ; * ; start--v v--change * ; _ _ _ * ; |||||| | |-2-10 1 2 3 4| |-2-10 1 2 3 4| | ||||| * ; |||||| | | | | | | ||||| * ; ||||||___.___| |_____________| |_____________| |__._||||| * ; Car 4 - pulse is 48uS * ; * ; change--v * ; _____________ _____________ _._ * ; |||||| | -2-10 1 2 3|4| -2-10 1 2 3|4| | ||||| * ; |||||| | | | | | | ||||| * ; ||||||___.___| |_| |_| |__||||| * ; Car 4 - pulse is 48uS-53uS * ; * ; Clearly time between rising edges is the critical item * ; Maximum cycle time for 6 cars, est 430uS * ; Therefore use a T0 /4 prescaler, to give 12 units per pulse * ; * ;********************************************************************** radix dec ;------------------------------------------------------------------------------ ; PROCESSOR DECLARATION ;------------------------------------------------------------------------------ LIST P=12F629 ; list directive to define processor #INCLUDE ; processor specific variable definitions LIST st=off ; -------------------------------- POS equ C ; +ve STATUS after subtraction SIGN equ 7 ; True bit if negative value ;--------------------------------- ; ; Branch if equal to destination BEQ MACRO lDest btfsc STATUS, Z goto lDest ENDM ; ; Branch if not equal to destination BNE MACRO lDest btfss STATUS, Z goto lDest ENDM ;------------------------------------------------------------------------------ #define _BANK1 bsf STATUS, RP0 #define _BANK0 bcf STATUS, RP0 ;------------------------------------------------------------------------------ ; ; #define BITSIZE 11 ; number of TMR0 counts to a bitpulse #define GOODREADS (3 -1) ; number of good reads reqd before send ;------------------------------------------------------------------------------ ; ; CONFIGURATION WORD SETUP ; ; The 'CONFIG' directive is used to embed the configuration word within the ; .asm file. The labels following the directive are located in the respective ; .inc file. See the data sheet for additional information on configuration ; word settings. ; ;------------------------------------------------------------------------------ __CONFIG _CP_OFF & _CPD_OFF & _BODEN_OFF & _MCLRE_ON & _WDT_OFF & _PWRTE_ON & _INTRC_OSC_NOCLKOUT ;_XT_OSC ;=================================== ; IO Port defines ; OUTb equ 0 ; Serial out to other system (ICSPdata) LED1b equ 1 ; Set Hi to light (ICSPclk) IR1b equ 2 ; Input from IR1, lo on detect ; equ 3 ; unused (MCLR) ; equ 4 ; xtal ; equ 5 ; xtal #define LED1 GPIO, LED1b #define OUT GPIO, OUTb #define IR1 GPIO, IR1b ;------------------------------------------------------------------------------ ; VARIABLE DEFINITIONS ;------------------------------------------------------------------------------ _temp res 1 cartime res 1 carcount res 1 car res 1 carhold res 1 carsent res 1 count res 1 halfway res 1 ;------------------------------------------------------------------------------ ; EEPROM INITIALIZATION ; ; The 12F629 has 128 bytes of non-volatile EEPROM, starting at address 0x2100 ; ;------------------------------------------------------------------------------ ; ;DATAEE CODE 0x2100 ;------------------------------------------------------------------------------ ; OSCILLATOR CALIBRATION VALUE ;------------------------------------------------------------------------------ OSC CODE 0x03FF ; Internal RC calibration value is placed at location 0x3FF by Microchip as ; a RETLW K instruction, where the K is a literal value to be loaded into ; the OSCCAL register. ;------------------------------------------------------------------------------ ; RESET VECTOR ;------------------------------------------------------------------------------ RESET_VECTOR CODE 0x0000 ; processor reset vector goto START ; go to beginning of program ;------------------------------------------------------------------------------ ; INTERRUPT SERVICE ROUTINE ;------------------------------------------------------------------------------ INT_VECTOR CODE 0x0004 ; interrupt vector location ; movwf W_TEMP ; save off current W register contents ; movf STATUS,w ; move status register into W register ; movwf STATUS_TEMP ; save off contents of STATUS register ; isr code can go here or be located as a call subroutine elsewhere ; movf STATUS_TEMP,w ; retrieve copy of STATUS register ; movwf STATUS ; restore pre-isr STATUS register contents ; swapf W_TEMP,f ; swapf W_TEMP,w ; restore pre-isr W register contents retfie ; return from interrupt ;------------------------------------------------------------------------------ ; MAIN CODE STARTS ;------------------------------------------------------------------------------ MAIN_PROG CODE ; Jump table for the various bit pulse times for cars ; entry: timer value in W, ; return: car # in W CarCalc btfsc cartime, 7 retlw 0 movf cartime, W clrf PCLATH addwf PCL, f car_table local i = 0 local c = 1 while i < (c +3) *BITSIZE -1 dt 0 i += 1 endw while c <= 6 car_val#v(i) ; set the car values while i < (c +3) *BITSIZE +(BITSIZE /2) dt c i += 1 endw car_val#v(i) ; set intercar gap while i < (c +1 +3) *BITSIZE -1 dt 0 i += 1 endw c += 1 endw while i < 128 dt 0 i += 1 endw ;------------------------------------------------------------------------------ ; MAIN PROGRAM ;------------------------------------------------------------------------------ START _BANK0 clrf GPIO movlw 7 movwf CMCON ;------------------------------------------------------------------------------ ; OSCCAL RESTORE (not required if internal OSC is not used) ;------------------------------------------------------------------------------ errorlevel -302 ; no warnings about non-bank 0 registers call 0x3FF ; retrieve factory calibration value banksel OSCCAL movwf OSCCAL ; update register with factory cal value ;------------------------------------------------------------------------------ movlw (0 << NOT_GPPU) | (1 << INTEDG) | (0 << T0CS) | (1 << T0SE) | (0 << PSA) | 0x01 movwf OPTION_REG movlw (1 << IR1b) | (0 << OUTb) | (0 << LED1b) movwf TRISIO movwf WPU errorlevel +302 banksel INTCON clrf INTCON movlw (1 << OUTb) | (0 << LED1b) movwf GPIO ; set a 'space' state on output line, & LEDs off clrf car ;------------------------------------------------------------------------------ ; a long high implies that the car is going over the sensor, and its in darkness long_silence movlw GOODREADS movwf carcount clrf carsent clrf carhold bcf LED1 ; wait for start pulse on inport (rising edge) await_start clrf TMR0 awaiting_start btfsc TMR0, 7 goto long_silence btfss IR1 goto awaiting_start ; (while lo) btfss IR1 goto awaiting_start ; (while lo) clrf TMR0 btfss IR1 goto awaiting_start ; (while lo) ; start has occured, now await the changing edge - this defines the 'lane switch or not' await_change btfsc IR1 goto await_change btfsc IR1 goto await_change btfsc IR1 goto await_change ; edge has restored, now check the duration - this must be 9 or more (11 optimum) Timer cycles to be valid movf TMR0, W movwf halfway movlw BITSIZE -3 subwf halfway, W btfss STATUS, C goto await_start ; edge is too short, must be noise, try again await_next_start btfsc TMR0, 7 ; if timer over runs, then a long silence has occurred goto long_silence btfss IR1 goto await_next_start btfss IR1 goto await_next_start btfss IR1 goto await_next_start ; do calcs in here for car id movf TMR0, W movwf cartime clrf TMR0 movlw BITSIZE -3 addwf halfway, W subwf cartime, W btfss STATUS, C goto await_change ; edge is too short, try again call CarCalc btfsc STATUS, Z ; check for illegal value goto await_change car_send movwf car movf carhold, w ; see if we've already got it before BNE check_send car_save movf car, w ; first time or new decode, save for recheck movwf carhold movlw GOODREADS movwf carcount goto await_change check_send movf carhold, w xorwf car, w ; second or later time, compare both BNE car_save decfsz carcount, f ; decode must be the same for GOODREADS times goto await_change movf car, w ; see if we already sent this car id xorwf carsent, w BEQ await_change ;------------------------------------------------------------------------------ ; All match, send the car number out bsf LED1 movf car, w movwf carsent movlw 0x30 iorwf car, f movlw 12 movwf count bcf STATUS, C tx_loop btfsc STATUS, C goto $ +4 nop ; send a lo bcf OUT goto $ +3 bsf OUT ; send a hi goto $ +1 call bit_delay ; pause for the remainder of the bit time bsf STATUS, C ; set a stop bit, and rotate the value rrf car, f decfsz count, f ; finish when all 11 bits sent goto tx_loop ; await a suitable end point, then loop again await_end btfsc IR1 goto await_end btfsc IR1 goto await_end btfsc IR1 goto await_end goto await_start ;------------------------------------------------------------------------------ ; Delay of: 17.3 (57600bd); -15 cycles (for mainline code, inc call/return) ; for 4MHz crystal (1 MHz cycle) bit_delay goto $ +1 retlw 0 END ; 'end of program'