Atmega32 Timer/Counter1 in Timer Mode

A Short Detail of Timer/Counter1

Timer/Counter1 module of Atmega32 is superior to Timer/Counter0. It has some advanced features over the previous one's:

• 16-bit wide made of two 8-bit registers
• Input capture mode
• Improved PWM mode
• Four interrupt source

It has two Timer/Counter registers working as a pair of two 8-bit low and high register - TCNT1H and TCNT1L. As a result the Timer/Counter registers is 16-bit in total.

Timer/Counter1 Register -TCNT1H and TCNT1L

There are more additional Timer/Counter control registers and interrupt flag. But we only list some in-use registers in this post.

Timer/Counter1 Control Register B (TCCR1B) contain functions setting of this module working in timer mode.

Timer/Counter1 Control Register B

Clock Select bit (CS12:10) of this register set the clock source of Timer/Counter1.

Timer/Counter1 Clock Select bit

Interrupt occurs at the maximum counting of this 16-bit Timer/Counter at 65536. Then the Timer/Counter1 overflow interrupt flag (TOV1) is set.

Timer/Counter Interrupt Flag Register - TIFR

Programming Timer/Counter1 in Timer Mode

In this Timer/Counter1 timer mode example, the program configure this module to make a timer tick of 262ms. This timer tick is a result of its interrupt at overflow. At the interrupt time PC2 of Port C toggles.

Schematic diagram of this example post

We have a calculation below.

Microcontroller instruction cycle with its 16MHz clock frequency is,

1/16000000 = 62.5ns

With a clock selection of Clk/64 we get,

64*62.5ns = 4us.

Sixteen bit Timer/Counter1 register counts up to 65536 value to generate the interrupt flag. The duration before the TOV1 is set is,

65536*4us = 262ms.

For every 262ms PC2 toggles an output LED.

/*
 * timer_1_example.c
 *
 * Created: 12/19/2020 8:57:35 PM
 * Author : aki-technical
 */ 
#include <avr/io.h>
int main(void)
{
    /*Select Timer Mode, CLK/64*/
TCCR1B=(1<<CS11)|(1<<CS10);
/*PC2 Output*/
DDRC=(1<<2);
/*Clear Timer Overflow Flag 1*/
TIFR=(1<<TOV1);
    while (1) 
    {
/*Check for overflow*/
if (TIFR&(1<<TOV1))
{
/*Clear this flag*/
TIFR=(1<<TOV1);
/*Toggle PB2*/
PORTC^=0x04;
}
    }
}

Let see the simulation result in software. 

Simulation result in Proteus

Click here to download this example file.