Exploration of AVR Timer

First, let's talk about the AVR8-bit general timer register T/C0:

There is one sentence that I don't quite understand: All interrupts can be individually masked through (timer interrupt mask register) TIMSK.

Explanation: The TIMSK register is a timer/counter interrupt mask register, which means that TIMSK can mask some interrupts individually.

The definitions for internal use are: BOTTOM: The counter reaches BOTTOM when it reaches 0x00 MAX: The counter reaches MAX when it reaches the maximum value

Clock source configuration: You can choose internal clock configuration or external clock configuration.

Counter operation: For the counter, the counter count always increases. When the counter value exceeds 0xff, it starts counting again from ox00. When the TCNT0 counter is set to 0, the overflow flag TOV0 is set.

TOV0 can be cleared by the timer overflow interrupt.

/* Now we will start to explore and study the timer*/

Timer operation: First, you must set the initial value. The general steps for setting the timer are: (1) configure the TIMSK register to enable the overflow interrupt for which timer; (2) configure the TCCRX register to set the clock source signal division rate; (3) configure the TCNTX register to set the initial value.

The most important point in using the interrupt function is to map the interrupt vector address to the correct place. Generally speaking, the interrupt vector address of the timer must be configured with the 0th bit - TVOX overflow flag in the TIFR register to determine whether to enter the timer interrupt. However, in AVR, directly mapping the interrupt overflow vector in the interrupt function name can also achieve this purpose:

interrupt [TIM2_OVF] void timer2_ovf_isr(void) //TIM2_OVF is the overflow flag of timer 2

After the timer interrupt is entered, it is generally necessary to reset the initial value of the timing TCNTX, and then write the code function.

So to summarize. Timer operation:

Initialization of the timer:

(1) Configure TIMSK interrupt overflow enable

(2) Configure TCCRX timer enable

(3) Configure TCNTX timer initialization

Timer interrupt settings:

(1) Function name configuration--must be consistent with the timer interrupt variable mapping

(2) After entering the function, it is best to initialize the initial value of the timer TCNTX