; PIC12C509 program to sense off/on state from a ; radio control receiver output. Outputs active ; if longer than 1.5mS; inactive if less. ; ; Inputs - R/C pulse input GP0 ;positive 1-2mS pulse every 25mS ; - Loss-of-signal control GP4 ;1 to turn on if signal lost ; - reset GP3 ;tie high ; Outputs - switch GP5 ;on when active ; - switch inverted GP1 ;off when active ; - flash GP2 ;1 second flashing when active LIST P=12C509 #include ; #include ;__CONFIG _CP_OFF & _WDT_OFF & _MCLRE_ON & _IntRC_OSC RADIX DEC GP0 equ 0 GP1 equ 1 GP2 equ 2 GP3 equ 3 GP4 equ 4 GP5 equ 5 DEBUG equ 0 ;1 to shorten delays; 0 otherwise AVERAGE_COUNT equ 20 ;number of 0.025mS passes to average FLASH_COUNT equ 40 ;flash threshold, number of 0.025mS pulses NO_SIGNAL_COUNT equ 66 ;number of 0.015mS delays in 1 second START_THRESHOLD equ AVERAGE_COUNT * 2 ;beginning count threshold OFF_THRESHOLD equ START_THRESHOLD - ( AVERAGE_COUNT / 2 ) ;below this, turn output off ON_THRESHOLD equ START_THRESHOLD + ( AVERAGE_COUNT / 2 ) ;above this, turn output on #if ( DEBUG == 1 ) DELAY15MS equ 255 ;short delay for debug DELAY500US equ 255 OK_COUNT equ 1 #else DELAY15MS equ 21 ;normal delays DELAY500US equ 248 OK_COUNT equ 133 #endif state_count equ 0x10 ;RAM pulse_count equ 0x12 flash_counter equ 0x13 ;number of 0.025 (nominal) pulses received so far flash_state equ 0x14 ;1 if flash output on, 0 if off no_signal_count equ 0x15 ORG 0x3ff movlw 0x40 ;RC calibration value ORG 0x400 dw _CP_OFF & _WDT_ON & _MCLRE_ON & _IntRC_OSC ;configuration fuses for PEP programmer ORG 0x0000 start: movwf OSCCAL ;load RC cal value movlw b'11011001' tris GPIO ;set GP1, GP2, GP5 for output, rest are inputs movlw 0x85 ;/64 clk prescaler, weak pullups, int clk option ;load option reg from W reg bcf GPIO,GP5 ;turn off switch bsf GPIO,GP1 ;turn on inverted switch call CLEAR_COUNTS clrf flash_counter ;BLINK FLASHER FOR TWO SECONDS TO SIGNAL THAT PROCESSOR IS OK movlw OK_COUNT ;do 30mS square wave for two seconds movwf pulse_count s1: bsf GPIO,GP2 ;turn on flasher output call DELAY_15MS ;delay bcf GPIO,GP2 ;turn off flasher output call DELAY_15MS ;delay another 0.5 second decfsz pulse_count goto s1 ;not done yet ;LOSS-OF-SIGNAL CONTROL - LOCKED HIGH FOR AT LEAST ONCE SECOND loop: movlw NO_SIGNAL_COUNT ;get count movwf no_signal_count ;save it l_1: movlw DELAY15MS ;15mS count movwf TMR0 ;set timer l_2: movf TMR0,W ;get count, set flags clrwdt ;keep watchdog alive btfss GPIO,GP0 ;jump if still high goto h_0 ;found low, jump to find rising edge btfss STATUS,Z ;skip if zero flag is set from timer goto l_2 ;timer not zero yet, loop decfsz no_signal_count ;decrement, skip out if zero goto l_1 ;do again goto lost ;signal lost ;LOSS-OF-SIGNAL CONTROL - LOCKED LOW FOR AT LEAST ONCE SECOND h_0: movlw NO_SIGNAL_COUNT ;get count movwf no_signal_count ;save it d_1: movlw DELAY15MS ;15mS count movwf TMR0 ;set timer d_2: movf TMR0,W ;get count, set flags clrwdt ;keep watchdog alive btfsc GPIO,GP0 ;jump if still low? goto d_3 ;found rising edge, jump (approx every 25mS) btfss STATUS,Z ;skip if zero flag is set from timer goto d_2 ;timer not zero yet, loop decfsz no_signal_count ;decrement, skip out if zero goto d_1 ;do again goto lost ;signal lost ;FOUND RISING EDGE OF PULSE d_3: call DELAY_500US ;wait 0.5mS btfss GPIO,GP0 ;is pulse still there? goto loop call DELAY_500US ;delay another 1.0mS call DELAY_500US ;CHECK AT 50% POINT IN PULSE TIME btfss GPIO,GP0 ;skip if pulse still there goto a0 ;pulse is gone incf state_count,F ;request turn on goto cont1 a0: decf state_count,F ;request turn off cont1: incf pulse_count,F ;increment the number of 0.025mS counts call DELAY_15MS incf flash_counter btfss GPIO,GP5 ;skip if output is on goto cont3 ;output is off movlw FLASH_COUNT ;output is on, get flash count subwf flash_counter,W ;check if above 40 counts yet btfss STATUS,C ;skip if enough passes to toggle flash state goto cont2 ;not enough passes movlw b'00000100' ;mask on GP2 xorwf GPIO,F ;toggle GP2 cont3: clrf flash_counter ;AVERAGING AND VALID THRESHOLDS cont2: movlw AVERAGE_COUNT ;check if enough pulses to average subwf pulse_count,W ;pulse_count minus average_count btfss STATUS,C ;jump if enough passes (no borrow) goto loop ;not enough passes yet movlw OFF_THRESHOLD ;check if state_count is below off threshold subwf state_count,W ;state_count minus off_threshold btfss STATUS,C ;jump if no borrow, maybe above on threshold ? goto toff ;below off threshold, turn output off movlw ON_THRESHOLD ;check if state_count is above on threshold subwf state_count,W ;state_count minus on_threshold btfss STATUS,C ;jump if no borrow, it's above on threshold goto loop ;not reached either off or on threshold yet, loop ;TURN ON OR OFF ton: bsf GPIO,GP5 ;turn on output switch bcf GPIO,GP1 ;turn off inverted switch call CLEAR_COUNTS goto loop toff: bcf GPIO,GP5 ;turn off output bsf GPIO,GP1 ;turn on inverted switch bcf GPIO,GP2 ;turn off flasher output call CLEAR_COUNTS goto loop lost: btfss GPIO,GP4 ;jump if want to turn on if signal lost goto toff goto ton ;=============================== DELAY_15MS: movlw DELAY15MS ;15mS count goto dhm_1 DELAY_500US: movlw DELAY500US ;500uS count dhm_1: movwf TMR0 ;set timer dhm_2: movf TMR0,W ;get count, set flags clrwdt ;keep watchdog alive btfss STATUS,Z ;skip if zero flag is set goto dhm_2 ;loop retlw 0 ;=============================== CLEAR_COUNTS: movlw START_THRESHOLD movwf state_count ;preset start threshold clrf pulse_count retlw 0 END