How to Implement Interrupts on PIC10F322 Using XC8 : An Overview

Implementing interrupts on PIC10F322 using the XC8 compiler is straightforward. This guide provides a quick overview to help you get started.

Defining the Interrupt Function

To handle interrupts, you need to define an interrupt function (also known as an interrupt service routine, or ISR) in your code.

void __interrupt () isr_routine (void)
{
    // Interrupt handling code here
}

• The function name (isr_routine) can be anything you choose.
• The __interrupt() keyword is crucial as it tells the XC8 compiler that this function is the interrupt handler.

Things to Keep in Mind

Clearing the Interrupt Flag

Inside your interrupt function, you must clear the interrupt flag for the device that caused the interrupt. Failing to do so will result in the interrupt continuously triggering.

void __interrupt() isr_routine(void)
{
    if (INTCONbits.TMR0IF) {  // Check if Timer0 caused the interrupt
        INTCONbits.TMR0IF = 0;  // Clear Timer0 interrupt flag
        // Handle Timer0 interrupt (e.g., toggle an LED)
    }
}

Setting Up Interrupts

In your setup function, you need to enable the interrupt for the specific device and also enable global interrupts (GIE).

void setup(void)
{
    // Configure Timer0
    OPTION_REGbits.T0CS = 0;  // Select internal clock (FOSC/4)
    OPTION_REGbits.PSA = 0;   // Assign prescaler to Timer0
    OPTION_REGbits.PS = 0b111;  // Set prescaler to 256
    
    TMR0 = 0;  // Clear Timer0 register
    INTCONbits.TMR0IE = 1;  // Enable Timer0 interrupt
    INTCONbits.GIE = 1;  // Enable global interrupts

    // Other setup code
}

Handling Multiple Interrupts

If multiple interrupts are enabled, your interrupt function must check the flags for each possible interrupt source you have enabled to determine which one triggered the interrupt.

Practical Example: Enabling Timer0 Interrupt

In the next post, we’ll cover a practical example of enabling a Timer0 interrupt to replace the __delay_ms() function, allowing for more efficient timing in your code.

Summary

Implementing interrupts on the PIC10F322 using XC8 involves defining an interrupt function with the __interrupt() keyword, clearing the interrupt flag within the ISR, and enabling the necessary interrupt and global interrupt flags in your setup function. By following these steps, you can efficiently handle interrupts and improve the responsiveness of your microcontroller applications.

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