How to convert PID output into meaningful result to feed into controller

Thanks you all, the reason I have PIC an pocketbeagle is because, PIC handles ZeroCross detection and creates software PWM according to the value supplied by pocketbeagle, which handles PID. I need to have USB,WiFI n LCD display and embedded webserver functionality that's why I chose poketbeagle and since it can't handle zero cross detection or any real time processing (unless I dive into PRU codes, which is a bit of a learning curve that I would want like to avoid at this stage), I moved the ZCD code to PIC. Unfortunately I can't post all the code here because it belongs to the company.

I fought with the PIC code for it to accept a string and then change that string to integer, I am doing the same at the moment but just for a single character instead of a string. If I can get a string and then itoa(str) then, I can have a bigger resolution instead of just 0 to 9  and that may solve the problem. For some reason the PIC halts or at least it stops activating the tirac used to switch coil. It always stops the coil and never gets stuck in ON position. Here is my PIC code.

#include <xc.h>
 #include <stdlib.h>
#include <math.h>
#include <stdint.h>
#include "main.h"
#include "UART.h"


// BEGIN CONFIG
#pragma config WDTE = OFF       // Watchdog Timer Enable bit (WDT disabled)
#pragma config PWRTE = OFF       // Power-up Timer Enable bit (PWRT enabled)
#pragma config BOREN = ON       // Brown-out Reset Enable bit (BOR enabled)
#pragma config LVP = OFF        // Low-Voltage (Single-Supply) In-Circuit Serial Programming Enable bit (RB3 is digital I/O, HV on MCLR must be used for programming)
#pragma config CP = OFF         // Flash Program Memory Code Protection bit (Code protection off)
#pragma config FEXTOSC = OFF    // External Oscillator mode selection bits (Oscillator not enabled)
#pragma config RSTOSC = HFINT1  // Power-up default value for COSC bits (HFINTOSC (1MHz))
//END CONFIG
int i=0;
int my_delay = 10000;
int t, value=0;
char zc;
char result[2];
char foo, buffer[3] ; // 10(0x0D))
char counter=0; 


void interrupt ISR(void)
{
    if(INTF) // check if RA2/INT interrupt is triggered.
        INTF=0;
         GIE=0;
        zc = 1;
        if(INTEDG)
            INTEDG =0;
        else
            INTEDG =1;
        GIE =1;
}


setup(void)
{
    TRISA4 = 0; //Set as output 
    TRISAbits.TRISA2 =1;
    ANSELAbits.ANSA2 =0;
    INLVLAbits.INLVLA2 = 1;
    INTPPS = 0x02;
    INTE =1;
    INTF = 0;
    INTEDG = 1;
    
    zc = 0; 


    PEIE =1;
    GIE=1;          //Enable Global Interrupt
    
   delay_ms(500);
}


delay_ms(unsigned int ms)
{
    while(ms > 0)
    {
        __delay_ms(1);
        ms--;
    }
}
void delay_10us(unsigned int us_count)
 {
    while(us_count!=0)
      {
        for(int i=0;i<11;i++)
        {
         __delay_us(1)  ;
us_count--;
        }
   }
   }






ser_process()
{
   char str[8];
   {
   UART_Read_Text(str,8);
   delay_ms(200);
   UART_send_string(str);
    }


#if 0 
    if(RC1IF)
    {


   foo = UART_get_char();
   buffer[counter]=foo;
   counter++;
   if(foo==0x0D)
   {
   buffer[counter]=0x00; // remove 0x0D
   my_delay = atoi(buffer);
   if(my_delay>9) // make sure not to overshoot
       my_delay=9;
   UART_send_string(buffer);
   itoa(result,my_delay,10);
   
   for(int i=0;i<3;i++)
   {
       buffer[i] =0x00;
      
   }
    counter = 0;
   
   }
             }


#endif
            
}
void main(void) 
{
  
    OSCCON1bits.NDIV = 0; // necessary 
    OSCFRQbits.HFFRQ = 0b011; // 8MHz
    
    Initialize_UART();
    setup();
    my_delay = 1;


        while(1)
            
        {


#if 1
            while(zc==0);
            
            {     
            delay_ms(0);  //THIS IS WHERE THE VALUE FROM PID SHOULD GO
            RA4 = 1;
            }
            __delay_us(500);
            RA4 = 0;
            zc = 0; 
#endif


          ser_process();
    
    

        }


    
    return;
}

I played around with it and found that even if I try to receive individual characters, it can't handle more than than three characters and then it gets stuck, the code still responds to UART but the heating coil stays off. In the above code I have hard coded for it to stay on (delay_ms(0)), and still it goes off, and  this is where I would want to use __delay_us instead, to get higher resolution, so I can send inputs e.g 34587, instead of just 3. So the question is why above code would suddenly turn the heating coil off ? while continue to respond to UART. Thanks

Chris,

In looking at your interrupt function:

void interrupt ISR(void)  
{  
    if(INTF) // check if RA2/INT interrupt is triggered.  
        INTF=0;  
         GIE=0;  
        zc = 1;  
        if(INTEDG)  
            INTEDG =0;  
        else  
            INTEDG =1;  
        GIE =1;  
} 

I am not sure if the initial 'if(INTF) is intended to qualify all of the remaining code, or if the indention is unintentional.  Without braces '{}' the only statement that is dependent on the 'if(INTF) statement is 'INTF=0', all the remaining statements are executed on any interrupt, which might be causing your code to set zc to one unexpectedly.

Not sure if this is part of your problem, or just me getting confused by the indention.

Good luck!

Gene

Chris,

In looking at your interrupt function:

void interrupt ISR(void)  
{  
    if(INTF) // check if RA2/INT interrupt is triggered.  
        INTF=0;  
         GIE=0;  
        zc = 1;  
        if(INTEDG)  
            INTEDG =0;  
        else  
            INTEDG =1;  
        GIE =1;  
} 

I am not sure if the initial 'if(INTF) is intended to qualify all of the remaining code, or if the indention is unintentional.  Without braces '{}' the only statement that is dependent on the 'if(INTF) statement is 'INTF=0', all the remaining statements are executed on any interrupt, which might be causing your code to set zc to one unexpectedly.

Not sure if this is part of your problem, or just me getting confused by the indention.

Good luck!

Gene