TRIAC firing from PIC MCU

[leaveme]

Hi,

I'm experimenting a project using PIC to fire the TRIAC. But I do not really understand to setup the TIMER interrupt. I'm using CCS C.
Any help will be appreciated.

//Compiler: CCS C - v4.14

#include <16F886.h> 

#fuses HS 
#FUSES NOPUT //No Power Up Timer
#FUSES NOPROTECT //Code not protected from reading
#FUSES NOMCLR //Master Clear pin NOT enabled
#FUSES BROWNOUT //Reset when brownout detected

#use delay(clock=20M)


#define DIM_LEVEL 65535
int1 ZC=FALSE; 


#INT_EXT                         //External Interrupt 
void  EXT_isr(void) 
{ 
   output_low(PIN_C0);             //make sure gate is OFF

   set_timer0(DIM_LEVEL);          //preload_time into Timer0
   enable_interrupts(INT_TIMER0);  //start Timer0

   ZC = TRUE;

}

#int_TIMER0 
void  TIMER0_isr(void) 
{ 
     if (ZC)   //execute if zero crossing occures 
     { 
        set_timer0(0);        //stop Timer0
        output_high(PIN_C0);  //turn the gate ON
        delay_uS(100); 
        output_low(PIN_C0);  //turn the gate OFF
        clear_interrupt(INT_TIMER0);  //clear Timer0
        ZC = FALSE; 
     }
} 

void main( void ) { 

   //drive all pins low, except B0, set as input 
   output_b(0); 
   output_c(0); 
   output_float(PIN_B0); 

   setup_timer_0( T0_INTERNAL | T0_DIV_1 ); 

   //ext_int_edge(H_TO_L); //set the falling edge to trigger on the ZC signal
   ext_int_edge(L_TO_H);   //set the rising edge to trigger on the ZC signal 

   clear_interrupt(INT_EXT); 

   enable_interrupts(INT_EXT);
   enable_interrupts(GLOBAL);

  while (1);

}

 

[zia]

may u share detail of ur work so that we help according to that or r u feeling problem just in timer interrupt.

 

[leaveme]

may u share detail of ur work so that we help according to that or r u feeling problem just in timer interrupt.

I'm working with a dimmer project using PIC.

 

[zia]

ok then it can be done with out timer by using zero crossing detector and ccs own delay rutine

 

[leaveme]

Can I vary the delay by ADC then?

 

[jean12]

Can I vary the delay by ADC then?

Yes,you can vary the firing angle with the ADC,see for example here below the codes I found somewhere,me I added only the ADC use which is varied with a variable resistor on AN0, on AN1 I am reading the temperature;see the codes but I don't know how implementing the timer for that you also you can help me because the variation I am getting are insufficient for the good operation.


See the codes:

#include"16f877a.h"
#device adc=10
#fuses HS,NOWDT,NOLVP,NODEBUG,NOCPD
#use delay(clock=4M)
#int_ext

//--------------START of variable for Pulse delay definition---------------
int valuet;
unsigned long value1;
unsigned int value3,delaya;

//--------------Ends of variable for Pulse delay definition---------------

//--------------START OF variable for temperature reading---------------
byte const digit[]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90}; //Changed this as there was error in the previous one

char display[2];
int value;
unsigned long volt;
unsigned int value2;
//--------------END  OF variable for temperature reading---------------

void isrext()
{
output_c(0xff);
delay_ms(1000);
}

void main() 
{
set_tris_a(0xff);
set_tris_b(0x01);
set_tris_c(0x00);
set_tris_d(0x00);

setup_comparator(NC_NC_NC_NC);
setup_adc(ADC_CLOCK_INTERNAL);
setup_adc_ports(ALL_ANALOG);
setup_vref(False);

//int x=0;
enable_interrupts(int_ext);
enable_interrupts(global);
ext_int_edge(H_TO_L);

while(1)
{
//------------------Temperature reading and display
set_adc_channel(0);
delay_us(100);
      //value=read_adc(); //Not required
 read_adc(ADC_START_ONLY);
  delay_us(100);
      value=read_adc(ADC_READ_ONLY);

      //volt=(value*500)/1023; //I changed this part of the code
          volt=(value*500)/1023;
         value2=volt;
   delay_us(1);
      output_high(PIN_D1);
      display[0]=value2/10;      
      output_c(digit[display[0]]);
     output_low(PIN_D0);
      delay_ms(1);

      output_high(PIN_D0);
      display[1]=value2%10;      
      output_c(digit[display[1]]);
   output_low(PIN_D1);
      delay_ms(1);



set_adc_channel(1);
delay_us(20);
read_adc(adc_start_only);
delay_us(20);
valuet=read_adc(adc_read_only);
value1=(valuet*500)/1023;
value3=value1;
delaya=(value3*20)/10;
//delaya=(value3);

output_high(PIN_D3);
delay_ms(delaya);
output_low(PIN_D3);


}
}

Good Luck,you also you help me on the timer for having a variation of voltage at the complete period.

Thanks.

 

[embpic]

if u are working on dimmer u should go with PWM if u r controller support it. because most of dimmer application pwm is very useful for dimmer.

regards.

 

[Venkadesh_M]

Do you want a pulse train or a single pulse to turn ON the TRIAC..?

If you just need a pulse means

=> Give the ZCD in a ext interrupt
=> when it invokes start a timer whose value is depend on the firing angle
=> in timer Isr Set the output pin
=> also clear all the output pins in ZCD (step 1)

 

[jean12]

I want to create a delay in interrupt which corresponds to the value reads from the variable resistor.

 

[Venkadesh_M]

exactly.....