************************************************************************* 
 **** 
 **** Digital ignition for 2 stroke engines. SPORTDEVICES 4/3/2005 
 **** 
 **** NOTE: use compiler: PCW v2.619 
 **** 
 **** Digital parts: PIC16F84a, XTAL 4MHz 
 **** Complete schematic: www.sportdevices.com/ignition/ignition.htm 
 **** To ask any question: [email protected] 
 **** 
 **** 
 ************************************************************************** 
 
 #include <16F84a.H> 
 #fuses XT,NOWDT,PUT 
 #use fast_io(a) 
 #use delay(clock=4000000) 
 
 //setup values 
 #define prescaler 7 //2^7=128 
 #define delay_multiple 8 //8 us, min 3 us 
 #define low_rpm_pulse true //does it generate pulses at low rpm? 
 #define low_rpm_multiple 40 //us, to calculate degrees at low rpm (8 * 2.5 = 40) 
 #define scr_pulse 200 //scr spark time, microseconds 
 #define pulse_polarity 0 //0-activates low 
 #define min_rpm 200 //min rpm value, if lower the program starts again 
 #define min_period 31 
 ****** 
 #define max_period 60000000/(2^prescaler)/min_rpm 
 
 int const ignition0[64]= 
 {48,49,51,52,54,56,57,59,60,62,64,65,67,68,70,72,73,75,76,78,80,81,83,84, 
 86,88,89,91,92,94,96,97,99,100,102,104,105,142,145,147,149,151,153,155,157, 
 160,162,164,166,168,170,172,174,177,179,181,183,185,187,189,192,194,196,198}; 
 
 
 int const ignition1[64]= 
 {22,23,25,27,29,31,33,35,37,39,41,44,46,49,51,54,56,59,62,65,68,70,73,77,80,83,86,89, 
 93,96,100,103,106,108,110,112,115,117,119,122,124,127,129,131,134,136,139,141,144,146, 
 149,151,154,157,159,162,165,167,170,173,175,178,181,184};*/ 
 
 //Note: Delay values are calculated in multiples of 4 microseconds 
 //first value is for 15121 RPM (TMR0 count=31) and last value is for 4987 RPM (TMR0 count=94) 
 
 
 #define pickup PIN_B0 //pin 6 
 #define thyristor PIN_A2 //pin 1 
 #define LED PIN_A4 //pin 1 
 #define curve_sel PIN_B2 //pin 8 
 #define inhibit PIN_B1 //pin 8 
 
 #byte TMR0=0x01 
 #byte PORTA=0x05 
 #byte PORTB=0x06 
 #byte INTCON=0x0b 
 #byte OPTION_REG=0x81 
 
 int tmr0h,perl,perh; 
 int16 per; 
 
 #define copy16(a,b) #asm \ 
 movf a,w \ 
 movwf b \ 
 movf &a+1,w \ 
 movwf &b+1 \ 
 #endasm 
 
 #int_global 
 void int_tmr0() 
 { 
 tmr0h++; 
 bit_clear(INTCON,2); 
 } 
 
 #inline 
 void wait_pulse() 
 { 
 #if pulse_polarity==0 
 while (!input(pickup)); //wait line goes high 
 while (input(pickup)); //wait line goes low 
 #else 
 while (input(pickup)); //wait line goes low 
 while (!input(pickup)); //wait line goes high 
 #endif 
 
 perl=TMR0; perh=tmr0h; 
 TMR0=0; tmr0h=0; 
 } 
 
 #inline activate_SCR() 
 { 
 output_high(inhibit); //switch OFF DC/DC converter (if present) 
 
 output_high(LED); // led off 
 output_high(thyristor); 
 delay_us(scr_pulse); 
 output_low(thyristor); 
 
 delay_us(500); //this value is TBD (to be defined) 
 output_low(inhibit); //switch ON DC/DC converter (if present) 
 } 
 
 void main(){ 
 int retardo; 
 boolean first=true; 
 
 INTCON=0xa0; //T0IE=1 
 OPTION_REG=prescaler-1; //PULLUP on, 2^prescaler=128 
 set_tris_a(0x01); 
 set_tris_b(0x05); //pin b2 input (curve selector), PIN B0 input (pickup) 
 
 output_low(LED); 
 delay_ms(50); 
 output_high(LED); 
 delay_ms(100); 
 
 while (true) 
 { 
 
 //first pulse is not processed because the period can not be calculated until the second pulse 
 if(first) { wait_pulse(); first=false; } 
 
 wait_pulse(); 
 
 copy16(perl,per); 
 
 if ((per>=min_period)&&(per { 
 perl=perl-min_period; 
 #ifdef ignition1 
 if(input(curve_sel)) 
 retardo=ignition1[perl]; 
 else 
 #endif 
 retardo=ignition0[perl]; 
 
 retardo=retardo-8; //delay adjust (substract 8*4=32 us) 
 //do delay 
 #asm 
 bucle: #endasm 
 delay_cycles(delay_multiple-3); 
 #asm 
 decfsz &retardo,f 
 goto bucle 
 #endasm 
 
 activate_SCR(); 
 } 
 
 else 
 { 
 if (per>=max_period) first=true; //if rpm is too slow, engine is stoped 
 
 #if (low_rpm_pulse) 
 else 
 if (per>=min_period+sizeof(ignition0)) 
 { 
 //do delay 
 perl++; 
 perh++; 
 #asm 
 loop2: #endasm 
 delay_cycles(low_rpm_multiple-3); 
 #asm 
 decfsz perl,f 
 goto loop2 
 decfsz perh,f 
 goto loop2 
 #endasm 
 
 activate_SCR(); 
 } 
 #endif 
 } 
 
 } //while 
 } //main