Timer Module (millis)

Overview

This module provides basic timer functionalities, such as initializing Timer0, handling interrupts, and tracking milliseconds since the timer was started.

timer0_init

Initializes Timer0 for time tracking. This function must be called before using any other timer-related functionality.

  • Enables Timer0 interrupt.

  • Sets the timer to 8-bit mode.

  • Driven by a 500 kHz clock.

  • Ensures the timer is synchronized to the system clock.

void timer0_init(void);

timer0_handle_interrupt

This function should be called from the main Interrupt Service Routine (ISR) whenever the Timer0 interrupt is triggered. It updates the internal time counter. Note that this function does not clear the interrupt flag (PIR3bits.TMR0IF); this must be done at the ISR level.

void timer0_handle_interrupt(void);

millis

Returns the number of milliseconds since timer0_init() was called. This is a safe function that disables interrupts momentarily to return a consistent value.

uint32_t millis(void);

Definitions and Notes

  • ISR Responsibility: The function timer0_handle_interrupt() does not clear the Timer0 interrupt flag. This is the responsibility of the top-level ISR.

  • Time Precision: The module keeps track of milliseconds, and the value returned by millis() reflects the time passed since the timer was initialized.