* DCF-77 SINGLE NIXIE CLOCK * Bruno Gavand * January, 2006 * www.micro-examples.com * * This code is given 'as this', without any garantee * Use it at your own risks ! * * PIC16F84A * 16 Mhz crystal, HS clock * * PORTA.0, in : DCF pulse input * PORTA.1, out : LED pulse repeater * PORTA.2, out : LED pulse synch * PORTA.3, in : SWITCH, pull-down * * PORTB.0->3, out : BCD to 74141 decoder * PORTB.4->5, undef : not connected * PORTB.6, in : voltage control * PORTB.7, out : 40 Khz pulse for nixie high voltage power supply * */ /* * constant definitions */ #define BLANK 0x0f // BCD code for nixie blanking #define MAXCOUNT 15625 // number of tmr0 overflows in 1 second #define ADJUST 0 // number of extra cycles in one second /* * following values are reduced * to give some flexibility to DCF-77 pulse reception */ #define timer_d_min 28000 // number of tmr0 overflows in 2 seconds #define timer_h_0 1400 // number of tmr0 overflows in 0.1 second #define timer_h_1 2800 // number of tmr0 overflows in 0.2 second /* * macro definitions */ #define putNibble(b) PORTB = b // write a BCD value for 74141 /* * RAM variables */ unsigned int tmrh ; // count of tmr0 overflows since pulse is high unsigned int tmrd ; // count of tmr0 overflows since pulse is down unsigned char bitnum ; // number of last valid bit received char last_bit ; // value of last valid bit received unsigned char parity ; // count of positive bits unsigned char full ; // set to 1 when sequence is complete unsigned char locked ; // set to 1 when clock has been adjusted unsigned char mode ; // 0:positive logic receiver, 1:negative logic receiver, 2:no receiver unsigned char mn ; // minutes in sequence progress unsigned char hh ; // hours in sequence progress unsigned int scaler ; // count of tmr0 overflows for RTC unsigned char ohh, omn, oss ; // RTC clock : hours, minutes, seconds unsigned char dhh, dmn, dss ; // display : hours, minutes, seconds unsigned char pwm ; // PWM output enable flag unsigned char vmax, vcurr ; // max and current value for selector unsigned char curr ; // selector choice /* * wait n times 25 ms */ void delay_25ms(unsigned char n) { while(n) { Delay_ms(25) ; n-- ; } } /* * display a value from 00 to 99 on nixie, tenths first and then units */ void mkDigit(unsigned char d) { putNibble(BLANK) ; delay_25ms(10) ; putNibble(d / 10) ; delay_25ms(16) ; putNibble(BLANK) ; delay_25ms(2) ; putNibble(d % 10) ; delay_25ms(12) ; } /* * select a digit from 0 to vmax * make the digit vcurr flash to show the current selected value * curr contains the digit displayed when the key is pressed */ void selectDigit(void) { unsigned char i, j, k ; pwm = 1 ; // turn nixie on i = 0 ; for(;;) { for(j = 0 ; j <= vmax ; j++) { for(k = 0 ; k < 10 ; k++) { putNibble(j) ; delay_25ms(1) ; putNibble(vcurr == j ? BLANK : j) ; delay_25ms(1) ; if(PORTA.F3) { putNibble(BLANK) ; delay_25ms(8) ; putNibble(j) ; pwm = 0 ; curr = j ; return ; } } } if(vcurr < 10) { i++ ; if(i == 3) { pwm = 0 ; curr = vcurr ; return ; } } } } /* * interrupt routine called 2500000/256 times by seconds */ void interrupt(void) { if(INTCON.T0IF) { PORTB.F7 = !PORTB.F7 & !PORTB.F6 & pwm ; // PORTB.F7 = !PORTB.F7 ; if(PORTA.F0 ^ mode) { tmrh++ ; if(tmrd > timer_d_min) { bitnum = 0 ; if(full) { ohh = hh ; omn = mn ; oss = 3 ; scaler = 0 ; locked = 1 ; } mn = hh = 0 ; parity = 0 ; full = 0 ; PORTA.F2 = 1 ; } tmrd = 0 ; } else { tmrd++ ; if(tmrh > 0) { if(tmrh > timer_h_1) { last_bit = 1 ; switch(bitnum) { case 21: mn++ ; break ; case 22: mn += 2 ; break ; case 23: mn += 4 ; break ; case 24: mn += 8 ; break ; case 25: mn += 10 ; break ; case 26: mn += 20 ; break ; case 27: mn += 40 ; break ; case 29: hh++ ; break ; case 30: hh += 2 ; break ; case 31: hh += 4 ; break ; case 32: hh += 8 ; break ; case 33: hh += 10 ; break ; case 34: hh += 20 ; break ; } if((bitnum != 28) && (bitnum != 35) && (bitnum != 58)) { parity++ ; } bitnum++ ; } else if(tmrh > timer_h_0) { if(bitnum == 20) { last_bit = -1 ; bitnum = 0 ; PORTA.F2 = 0 ; } else { last_bit = 0 ; bitnum++ ; } } else { last_bit = -1 ; bitnum = 0 ; PORTA.F2 = 0 ; } if(bitnum == 21) { parity = 0 ; } if((bitnum == 29) || (bitnum == 36) || (bitnum == 59)) { if((parity & 1) != last_bit) { bitnum = 0 ; PORTA.F2 = 0 ; } parity = 0 ; } if(bitnum == 59) { full++ ; } } tmrh = 0 ; } scaler++ ; if(scaler > MAXCOUNT) { // TMR0 += ADJUST ; scaler = 0 ; oss++ ; if(oss == 60) { oss = 0 ; omn++ ; if(omn == 60) { omn = 0 ; ohh++ ; if(ohh == 24) { ohh = 0 ; } } } } PORTA.F1 = PORTA.F0 ^ mode ; INTCON.T0IF = 0 ; } } /* * program entry point */ main() { TRISA = 0b00001001 ; // see header TRISB = 0b01000000 ; // see header INTCON = 0b10100000 ; // T0IF and GIE enabled OPTION_REG = 0b11011000 ; // no prescaler locked = 0 ; vcurr = EEPROM_Read(0) ; // get last mode /* * select mode from 0 to 2 * mode 0 : positive DFC pulse * mode 1 : negative DCF pulse * mode 3 : no DCF, manual adjustment */ vmax = 2 ; selectDigit() ; mode = curr ; // new mode /* * if mode 2 (no DCF), proceed to hour and minute settings */ vcurr = 10 ; if(mode == 2) { /* * tenth of hours */ vmax = 2 ; selectDigit() ; ohh = curr * 10 ; /* * units of hours */ vmax = 9 ; selectDigit() ; ohh += curr ; /* * tenth of minutes */ vmax = 5 ; selectDigit() ; omn = curr * 10 ; /* * units of minutes */ vmax = 9 ; selectDigit() ; omn += curr ; /* * seconds must be 3 in advance, due to display system */ oss = 3 ; /* * clock is adjusted, lock it */ locked = 1 ; } EEPROM_Write(0, mode) ; // store selected mode /* * main loop */ for(;;) { /* * if not locked, no display to prevent * radio emission from high voltage supply * that could perturb DCF receiver */ if(locked > 0) { if(PORTA.F3) { /* * enter edit sleep mode */ for(dhh = 0 ; dhh < 24 ; dhh++) { pwm = 1 ; // turn nixie on mkDigit(dhh) ; // display hours vcurr = EEPROM_Read(0x10 + dhh) ; // get current sleep mode for hour vmax = 1 ; // range from 0 to 1 selectDigit() ; // select new value EEPROM_Write(0x10 + dhh, curr) ; // store choice in EEPROM } } else { /* * otherwise, start display cycle */ PORTB = BLANK ; pwm = 1 ; // turn nixie on delay_25ms(1) ; /* * time values have to be stored in other variables * in order to prevent changes during display */ dss = oss ; dmn = omn ; dhh = ohh ; mkDigit(dhh) ; mkDigit(dmn) ; mkDigit(dss) ; pwm = 0 ; // make nixie extinguish if(EEPROM_Read(0x10 + dhh)) { /* * display time, just make a short pause */ delay_25ms(60) ; } else { /* * sleep time */ if(mode == 2) { /* * long pause when no dcf receiver */ delay_25ms(255) ; } else { /* * dcf receiver is there, * unlock to allow new sync * meanwhile there will be no PWM activity */ locked = 0 ; } } } } } }