timer_10mS

 1. Preprocessor Directives:

• #include <pic.h>: Includes the header file pic.h, which contains definitions and declarations specific to PIC microcontrollers.

2. main() Function:

• Initialization:

  • TRISC = 0;: Configures PORTC as output pins.
  • PORTC = 0;: Clears the output pins on PORTC.
  • T0CS = 0;: Selects the internal clock source (Fosc/4) for TMR0.
  • PSA = 0;: Assigns the prescaler to TMR0.
  • PS2 = 1; PS1 = 1; PS0 = 1;: Sets the prescaler to 256, providing a timer tick every 50 milliseconds.
  • TMR0 = 217;: Initializes TMR0 with the value 217 to generate a 10ms delay.
  • RC0 = 1;: Sets the output on RC0.

• Main Loop:

  • while (1) { ... }: The main loop continues indefinitely.
  • Interrupt Handling:
    • if (T0IF) { ... }: Checks if the TMR0 interrupt flag is set.
    • TMR0 = 217;: Reloads TMR0 with the value 217 to start another 10ms delay.
    • RC0 = !RC0;: Toggles the RC0 output.
    • T0IF = 0;: Clears the TMR0 interrupt flag.

Explanation:

The code implements a simple square-wave generator that toggles an output pin (RC0) every 10 milliseconds. The main components of the code are:

• Timer Initialization: TMR0 is configured as an internal timer with a prescaler of 256, providing a timer tick every 50 milliseconds. The initial value of TMR0 is set to 217 to generate a 10ms delay.
• Interrupt Handling: The TMR0 interrupt is used to toggle the output pin and reload the timer for the next 10ms delay.

#include <pic.h>

void main()
{
TRISC=0;    // PORTC output
PORTC=0;   

T0CS=0;        // Internal Mode (Fosc/4)
PSA=0;        // Prescaler assigned to TMR0
PS2=1;
PS1=1;
PS0=1;        // Prescaler ratio 1:256

TMR0=217;    // (256-39=217) for 10mS time (10000=39x256)
RC0=1;        // output on
while(1)   
{
    if(T0IF==1){
    TMR0=217;   
   
    RC0=!RC0; // RC0 toggle       

    T0IF=0;
    }
}
}