ATmega88 datasheet(134/340 Pages) ATMEL

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134

7530H–AVR–02/09

ATmega48/88/168 Automotive

• Bit 1 – OCF1A: Timer/Counter1, Output Compare A Match Flag

This flag is set in the timer clock cycle after the counter (TCNT1) value matches the Output

Compare Register A (OCR1A).

Note that a Forced Output Compare (FOC1A) strobe will not set the OCF1A Flag.

OCF1A is automatically cleared when the Output Compare Match A Interrupt Vector is exe-

cuted. Alternatively, OCF1A can be cleared by writing a logic one to its bit location.

• Bit 0 – TOV1: Timer/Counter1, Overflow Flag

The setting of this flag is dependent of the WGM13:0 bits setting. In Normal and CTC modes,

the TOV1 Flag is set when the timer overflows. Refer to Table 14-4 on page 129 for the TOV1

Flag behavior when using another WGM13:0 bit setting.

TOV1 is automatically cleared when the Timer/Counter1 Overflow Interrupt Vector is executed.

Alternatively, TOV1 can be cleared by writing a logic one to its bit location.

15. 8-bit Timer/Counter2 with PWM and Asynchronous Operation

Timer/Counter2 is a general purpose, single channel, 8-bit Timer/Counter module. The main

features are:

• Single Channel Counter

• Clear Timer on Compare Match (Auto Reload)

• Glitch-free, Phase Correct Pulse Width Modulator (PWM)

• Frequency Generator

• 10-bit Clock Prescaler

• Overflow and Compare Match Interrupt Sources (TOV2, OCF2A and OCF2B)

• Allows Clocking from External 32 kHz Watch Crystal Independent of the I/O Clock

15.1

Overview

A simplified block diagram of the 8-bit Timer/Counter is shown in Figure 15-1. For the actual

placement of I/O pins, refer to “Pinout ATmega48/88/168” on page 2. CPU accessible I/O Regis-

ters, including I/O bits and I/O pins, are shown in bold. The device-specific I/O Register and bit

locations are listed in the “8-bit Timer/Counter Register Description” on page 146.

The PRTIM2 bit in “Power Reduction Register - PRR” on page 39 must be written to zero to

enable Timer/Counter2 module.

ATmega88 Datasheet(PDF) 134 Page - ATMEL Corporation