Understanding the TRISA Register on the PIC10F322 in XC8

The TRISA register on the microcontroller is essential for controlling the direction of pins on Port A. Here's a detailed explanation of how it works and how to configure it using .

Basics of the TRISA Register

The TRISA register determines whether a pin on Port A is an input or an output:

  • Setting a bit in the TRISA register to 0 configures the corresponding pin as an output.
  • Setting a bit to 1 configures the corresponding pin as an input.

Upon power-on or reset, all pins are set to input mode by default.

Configuring Pin RA0 as an Output

To set pin RA0 as an output, follow these steps:

Disable Analog Functionality:

This step is crucial because analog mode is enabled by default, and it must be disabled to use the pin for digital I/O.

ANSELAbits.ANSA0 = 0; // Disable analog mode for RA0

Set the Pin Direction:

TRISAbits.TRISA0 = 0; // Set RA0 as an output

Set the Pin High:

Once RA0 is configured as an output, you can control its state (high or low) using the LATA register.

LATAbits.LATA0 = 1; // Set RA0 high

Set the Pin Low:

LATAbits.LATA0 = 0; // Set RA0 low

Important Note about Pin RA3

Pin RA3 can only be configured as an input. You cannot set RA3 as an output.

Example Code

Here's a complete example demonstrating how to configure RA0 as an output and control its state:

This example sets RA0 as an output, makes it high for 1 second, and then sets it low. The __delay_ms() function is used to create a delay, assuming _XTAL_FREQ is defined currectly.

void main(void) {
    // Disable analog mode for RA0
    ANSELAbits.ANSA0 = 0; 

    // Set RA0 as an output
    TRISAbits.TRISA0 = 0; 

    // Set RA0 high
    LATAbits.LATA0 = 1; 

    __delay_ms(1000); // Wait for 1 second

    // Set RA0 low
    LATAbits.LATA0 = 0; 

    while(1) {
        // Main loop


Understanding and configuring the TRISA register is fundamental for controlling the direction of pins on the PIC10F322. By following the steps outlined above, you can effectively manage input and output configurations, ensuring your microcontroller operates as intended.

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