LIST P=16F914, R=DEC INCLUDE "p16F914.inc" __CONFIG _DEBUG_OFF & _FCMEN_OFF & _IESO_OFF & _BOD_OFF & _CPD_OFF & _CP_OFF & _MCLRE_ON & _PWRTE_ON & _WDT_OFF & _INTOSCIO #define thrs 0x12 ; initial clock time setup #define tmin 0x00 #define updateH 0x22 ; clock time of time sync #define updateM 0x01 #define maxAttempts 3 ; log of # of consequtive sync attempts #define RXout PORTB,5 ; setup RX control pins #define RXhold PORTC,1 #define RXpower PORTD,1 #define tZone -6 ; setup for CST time zone #define zeroL 2 ; zero durtion threshold for PIC @ 32 KHz #define zeroH 4 #define oneL 7 ; one duration threshold #define oneH 9 #define synL 2 ; sync pulse duration threshold #define synH 14 CBLOCK 0x20 ; data segment in BANK_0 w_save, stat_save ; saving regs while in interrupt hrs:2, min, days:2, year:2 ; storage for RX time temp ; temp variable ENDC CBLOCK 0x70 ; data segment in the shared area minutes, hours24, hours12, sec15 ; time keeping variables start, length ; storage for RX pulse start & width pulse ; storage for received pulse value pulseNo, wwvbByte ; pulse number and byte received state ; receiver FSM state synCnt ; counter for # of sync attempts ENDC ORG 0 goto main ORG 4 ; ISR bcf RXhold ; put RX on hold movwf w_save ; save Wreg swapf STATUS, w ; save stat reg without movwf stat_save ; changing flags btfss INTCON, RBIF ; PORTB interrupt? goto TMR1_int ; NO - check for timer interrupt btfsc RXout ; end of RX pulse? goto pulseEnd ; YES - process end of pulse pulseStart movf TMR1H, w ; get pulse start timestamp movwf start goto TMR1_int ; check for timer interrupt pulseEnd movf start, w subwf TMR1H, w ; compute pulse duration btfss STATUS, C ; is it < 0 ? addlw 0xEF ; YES - correct it movwf length call processPulse TMR1_int btfss PIR1, TMR1IF ; TMR1 interrupt? goto ISR_end ; NO - exit bcf PIR1, TMR1IF ; clear TMR1 interrupt flag movlw 0x10 ; setup next TMR1 int in 15 seconds movwf TMR1H incf sec15, f btfss sec15, 2 ; has 1 minute passed? goto ISR_end ; NO - exit incf synCnt, f ; update sync counter clrf sec15 movlw 7 ; increment minutes addwf minutes, w ; with BCD correction btfss STATUS, DC addlw -6 movwf minutes sublw 0x60 btfsc STATUS, Z ; minutes = 60? clrf minutes ; YES - clear minutes call displayMinutes movf minutes, w btfss STATUS, Z ; is hours update needed? goto ISR_end ; NO - proceed movlw 7 ; YES - increment hours addwf hours24, w ; with BCD correction btfss STATUS, DC addlw -6 movwf hours24 movf hours24, w sublw 0x24 ; hours = 24? btfsc STATUS, Z clrf hours24 ; YES - clear hours call displayHours ISR_end btfss INTCON, RBIF ; was it PORTB interrupt? goto $+3 ; NO - exit bsf RXhold ; YES - re-enable RX AGC bcf INTCON, RBIF ; and clear interrupt flag swapf stat_save, w ; get original flags in STATUS movwf STATUS swapf w_save, f ; restore Wreg swapf w_save, w retfie encode7seg ; pabcdefg andlw 0x0F addwf PCL, f retlw b'01111110' ; code for 0 retlw b'00110000' ; code for 1 retlw b'01101101' ; code for 2 retlw b'01111001' ; code for 3 retlw b'00110011' ; code for 4 retlw b'01011011' ; code for 5 retlw b'01011111' ; code for 6 retlw b'01110000' ; code for 7 retlw b'01111111' ; code for 8 retlw b'01111011' ; code for 9 retlw b'01110111' ; code for A retlw b'00011111' ; code for B retlw b'01001110' ; code for C retlw b'00111101' ; code for d retlw b'01000111' ; code for F main clrf PORTA clrf PORTB clrf PORTC clrf PORTD clrf ADCON0 ; ADC off bsf STATUS, RP0 ; change to BANK 1 movlw 7 movwf CMCON0 ^ 0x80 ; comparators off clrf ANSEL ^ 0x80 ; all inputs digital movlw b'00000001' movwf OSCCON ^ 0x80 ; internal oscillator @31KHz clrf TRISA ^ 0x80 ; STEP 1: set I/O ports clrf TRISB ^ 0x80 clrf TRISC ^ 0x80 clrf TRISD ^ 0x80 bsf PIE1 ^ 0x80, TMR1IE ; enable TMR1 interrupt bsf IOCB ^ 0x80, IOCB5 ; enable interrupt on change on PORTB:5 bcf STATUS, RP0 bsf STATUS, RP1 ; switch to BANK 2 bsf LCDCON ^ 0x100, VLCDEN ; STEP 2: enable LCD bias voltage pins bcf LCDCON ^ 0x100, CS1 ; STEP 3: select clock source (TMR1/32) bsf LCDCON ^ 0x100, CS0 bcf LCDCON ^ 0x100, LMUX1 ; STEP 4: select multiplex mode (static) bcf LCDCON ^ 0x100, LMUX0 bcf LCDPS ^ 0x100, WFT ; STEP 5: select waveform type (A) bcf LCDPS ^ 0x100, BIASMD ; STEP 6: select Bias mode (static) bcf LCDPS ^ 0x100, LP3 ; STEP 7: select refresh rate (64Hz) bcf LCDPS ^ 0x100, LP2 ; 1:3 bsf LCDPS ^ 0x100, LP1 bsf LCDPS ^ 0x100, LP0 movlw 0xFF ; step 8: enable LCD segment lines movwf LCDSE0 ^ 0x100 movwf LCDSE1 ^ 0x100 bcf LCDSE1 ^ 0x100, SE15 ; disable SEG15 movwf LCDSE2 ^ 0x100 clrf LCDDATA0 ^ 0x100 ; step 9: clear segment data registers clrf LCDDATA1 ^ 0x100 clrf LCDDATA2 ^ 0x100 bsf LCDCON ^ 0x100, LCDEN ; step 10: turn on the LCD driver module bcf LCDCON ^ 0x100, SLPEN ; enable LCD in sleep mode bcf STATUS, RP1 ; back to BANK 0 clrf sec15 ; setup initial time movlw tmin movwf minutes movlw thrs movwf hours24 call displayMinutes call displayHours clrf TMR1L ; setup TMR1 overflow in 15 seconds movlw 0x10 movwf TMR1H movlw b'00111111' ; 1:8 prescaler. LP oscillator movwf T1CON ; start timer bcf PIR1, TMR1IF ; clear interrupt flag bsf INTCON, PEIE ; enable periferal interrupt bsf INTCON, GIE ; enable interrupts call syncTime loop sleep nop movf hours24, w ; time for sync? sublw updateH ; sync is performed as soon as the clock time btfss STATUS, Z ; is updateH:updateM:45 goto loop ; thus giving 15 seconds for receiver to warm up movf minutes, w sublw updateM btfss STATUS, Z goto loop movf sec15, w sublw 3 btfss STATUS, Z goto loop call syncTime ; YES - do time synchronization goto loop ;////////////////// Time setting procedures syncTime bsf STATUS, RP0 ; switch to BANK_1 bsf RXout ; enable input at this pin bcf STATUS, RP0 ; back to BANK_0 bsf RXpower ; turn on receiver bsf RXhold ; turn on AGC btfss RXout ; wait for the pulse absence goto $-1 clrf state ; start in state 0 clrf synCnt ; clear the attempts counter bcf INTCON, RBIF ; clear interrupt flag bsf INTCON, RBIE ; enable PORTB onchange interrupt st_loop sleep ; wait for reaching state 3 nop ; or sync failure movf state, w andlw 3 sublw 3 btfsc STATUS, Z goto $+3 btfss synCnt, maxAttempts goto st_loop bcf INTCON, RBIE ; disable PORTB onchange interrupt bcf RXhold ; turn off AGC bcf RXpower ; turn off receiver bcf RXout ; preset 0 at this pin bcf INTCON, RBIF ; clear interrupt flag bsf STATUS, RP0 ; switch to BANK_1 bcf RXout ; configure this pin for output bcf STATUS, RP0 ; back to BANK_0 btfsc synCnt, maxAttempts ; was sync syccessful? return ; NO - keep old time movf min, w ; YES - use received time to set clock andlw 0x7F movwf minutes movf hrs, w movwf hours24 movlw 3 ; force the minute update movwf sec15 clrf TMR1L bsf PIR1, TMR1IF ; set TMR1 interrupt flag movf minutes, w btfss STATUS, Z call displayHours return processPulse movf state, w andlw 3 sublw 3 btfsc STATUS, Z return ; stay in state 3 once it is reached movlw 4 movwf pulse ; initialize pulse value movlw zeroL ; check for received 0 subwf length, w btfss STATUS, C goto srt ; too short pulse - ignore it movlw zeroH+1 ; check for received 0 subwf length, w btfss STATUS, C goto r0 ; accept pulse as 0 movlw oneL ; check for received 1 subwf length, w btfss STATUS, C goto srt ; too short for 1 - ignore movlw oneH+1 ; check for received 1 subwf length, w btfss STATUS, C goto r1 ; accept pulse as 1 movlw synL ; check for received sync subwf length, w btfss STATUS, C goto srt ; too short for sync - ignore movlw synH+1 ; check for received sync subwf length, w btfss STATUS, C goto rS ; accept pulse as sync srt decf pulse, f ; out of range duration: pulse=0 r0 decf pulse, f ; received 0: pulse=1 r1 decf pulse, f ; received 1: pulse=2 rS decf pulse, f ; sync signal: pulse=3 btfss STATUS, Z ; validate pulse duration goto accept clrf state ; illegal duration - return to state 0 return accept movf state, w ; at this point the pulse duration is legal andlw 0x03 addwf PCL, f ; get to one of the FSM states goto sync1 goto sync2 goto getByte sync1 ; state 0: waiting for the first sync pulse movlw 3 subwf pulse, w ; Z=0: sync btfsc STATUS, Z ; was it sync pulse ? incf state, f ; YES - enter state 1 return ; otherwise keep waiting for sync sync2 ; state 1: waiting for the second sync pulse clrf state movlw 3 subwf pulse, w ; Z=0: sync btfss STATUS, Z ; was it sync pulse ? return ; NO - keep waiting incf state, f ; YES - enter state 2 incf state, f movlw 9 ; prepare to receive 9 pulses movwf pulseNo return getByte ; state 2: receiving a bit call getBit ; analyse the received bit and shift it into addlw 0 ; the wwvb byte if accepted btfss STATUS, Z ; is byte complete ? return ; NO - wait for another bit movf state, w ; save the received byte wwvbByte andlw 0xF0 ; in one of time holding variables depending movwf temp ; on the byte number in temp swapf temp, f ; the byte numbers start with 1 movf wwvbByte, w decf temp, f btfsc STATUS, Z movwf min ; load minutes decf temp, f btfsc STATUS, Z movwf hrs ; load hours decf temp, f btfsc STATUS, Z movwf days+1 ; load day # (first byte) decf temp, f btfsc STATUS, Z movwf days ; load day # (second byte) decf temp, f btfsc STATUS, Z movwf year+1 ; load year (first byte) decf temp, f btfss STATUS, Z return movwf year ; load year (second byte) + leap info incf state, f ; the 59th sync bit is received ; and we enter state 3 correctHours movlw 0x3F andwf hrs, f movlw tZone ; correct hours wrt time zone btfsc year, 0 ; summer time correction addlw 1 addwf hrs, f movlw 36 btfss STATUS, C addwf hrs, f movlw -6 btfss STATUS, DC addwf hrs, f return getBit decf pulseNo, f ; update # of pulses to receive movlw 5 subwf pulseNo, w ; bit #5 is meaningless btfsc STATUS, Z retlw 1 ; ignore it movlw 3 ; if sync is received we either complete subwf pulse, w ; the byte or return back to state 0 btfss STATUS, Z goto addBit ; the received bit is not sync - process it movf state, w ; the received bit is sync - check for clrf state ; byte completion; in this case pulseNo=0 incf state, f movf pulseNo, f btfss STATUS, Z ; pulseNo = 0? retlw 1 ; NO - error; return to state 1 addlw 16 ; YES - update the byte number movwf state movlw 10 movwf pulseNo ; reset # of pulses to receive retlw 0 ; signal processing request to the caller addBit movlw 2 ; now we know that either 1 or 0 is received subwf pulse, w ; C = pulse rlf wwvbByte, f ; shift in the received bit retlw 1 ;///////////////// Time keeping procedures displayMinutes bsf STATUS, RP1 ; switch to BANK 2 movf minutes, w call encode7seg movwf LCDDATA0 ^ 0x100 swapf minutes, w call encode7seg movwf LCDDATA1 ^ 0x100 movlw 0x12 ; display AM/PM subwf hours24, w btfsc STATUS, C bsf LCDDATA0 ^ 0x100, 7 bcf STATUS, RP1 ; back to BANK 0 return displayHours bsf STATUS, RP1 ; switch to BANK 2 movf hours24, w sublw 0x12 btfss STATUS, C addlw 0x12 sublw 0x12 movwf hours12 ; hours12 = time in AM/PM andlw 0x0E ; BCD correction sublw 0x0D movf hours12, w btfss STATUS, C addlw -6 ; WREG = corrected time call encode7seg movwf LCDDATA2 ^ 0x100 btfsc hours12, 4 bsf LCDDATA2 ^ 0x100, 7 ; display tens of hours bcf STATUS, RP1 ; back to BANK 0 return END