Phasenanschitt Grundlagen

unsigned char ucADCH;

unsigned char ucADCL;

unsigned char ucTempSensor = 0;

unsigned char ucTempSensorCopy = 0;

unsigned char ucTMR1Active = 0;

#include <interrupt.h>

void main() {

  OPTION_REG = 0b01001000;             //pull-up enabled, INTE rising, Prescaler WDT, 1:1

  WPUA = 0b00000000;                   //all pull-ups on PORTA disabled

  WPUB = 0b00000000;                   //all pull-ups on PORTB disabled

  ANSEL = 0b00000001;                  //analog Input on AN0

  ANSELH = 0b00000000;                 //no more Analog Inputs

  CM1CON0 = 0x00;                      //all comparators disabled

  CM2CON0 = 0x00;

  ADCON0 = 0b10000001;                 //result right justified, reference VDD, AN0, ADC  enabled

  ADCON1 = 0b01010000;                 //Fosc/2 250ns per TAD 0b00000000, Fosc/16 0b01010000 better, but 2us per TAD

  INTCON.PEIE = 1;

  INTCON.INTE = 1;

  INTCON.T0IE = 1;

  PIE1.ADIE = 1;

  TMR0 = 205;

  TRISA = 0b00000101;                  //RA0 and RA2 are inputs

  TRISB = 0x00;

  TRISC = 0x00;

  PORTA = 0b00000010;                  //RA1 set to high

  PORTB = 0x00;

  PORTC = 0x00;

  INTCON.GIE = 1;

  ADCON0.GO_DONE = 1;

  while(1)

  {

  }

}

void interrupt()

{

    if (INTCON.INTF)

     {

        INTCON.INTF = 0;

        OPTION_REG ^= 0x40;                             //toggle Interrupt on falling/rising edge of RA2/INT pin

        ucTMR1Active = 1;                               //actived ingition of the Triac

        ucTempSensorCopy = ucTempSensor;                //transfer 10-bit resolution of the ADC to 8-Bit

        INTCON.T0IF = 1;                                //set the interrupt of the timer0

     }

     if (INTCON.T0IF)

     {

        INTCON.T0IF = 0;

        if (ucTMR1Active && !(--ucTempSensorCopy))      //decrements the value of usTempSensorCopy

        {                                               //true if usTempSensorCopy=0 and ucTMR1Active=1

           PORTB.RB4 = 1;                               //Ignition triac

           ucTMR1Active = 0;                            //deactived ingition of the Triac

           ADCON0.GO_DONE = 1;                          //read analog

        }

        TMR0 = 205;

        PORTB.RB4 = 0;

     }

     if (PIR1.ADIF)

     {

         PIR1.ADIF = 0;

         ucADCL = ADRESL;

         ucADCH = ADRESH;

         ucTempSensor = ((ucADCH << 6) | (ucADCL >> 2));//divided 1024Bit/4

         if (!ucTempSensor)

            ucTempSensor = 1;                           //avoid decrement of 0

     }

}

Berechnungen:

Prozessortakt: 8MHz  Zyklustakt: 2MHz  Zykluszeit: 0,5µs

Frequenz: 50Hz  Länge einer Halbwelle: 10ms

I.Sprung in Interrupt-Routine: 9 Cycles  4,5µs

II.Sprung aus Interrupt-Routine: 8 Cycles  4µs

III.INTF: 11 Cycles  5,5µs

IV.T0IF(ucTMR1Actvie=0 ODER usTempSensorCopy>0): 10 Cycles  5µs

V.T0IF: 16 Cycles  8µs

256 mögliche Zündpunkte in einer Halbwelle:

256 * I + 256 * II + III + 255 *IV + V = 3,464ms

10ms – 3,464ms = 6,536ms

6,536ms/256 = 25,53µs

25,53µs/0,5µs = 51,06

256 – 51 = 205

TMR0 muss immer mit 221 beschrieben werden (kein Prescaler)