ATMEGA48 datasheet(140/374 Pages) ATMEL

140 / 374 page

140

2545J–AVR–12/06

ATmega48/88/168

16. 8-bit Timer/Counter2 with PWM and Asynchronous Operation

16.1

Features

• 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

16.2

Overview

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

block diagram of the 8-bit Timer/Counter is shown in Figure 16-1. For the actual placement of

I/O pins, refer to ”Pinout ATmega48/88/168” on page 2. CPU accessible I/O Registers, 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 ”Register Description” on page 153.

The PRTIM2 bit in ”Minimizing Power Consumption” on page 41 must be written to zero to

enable Timer/Counter2 module.

Figure 16-1. 8-bit Timer/Counter Block Diagram

Clock Select

Timer/Counter

OCRnA

OCRnB

TCNTn

Waveform

Generation

Waveform

Generation

OCnA

OCnB

Fixed

TOP

Value

Control Logic

= 0

TOP

BOTTOM

Count

Clear

Direction

TOVn

(Int.Req.)

OCnA

(Int.Req.)

OCnB

(Int.Req.)

TCCRnA

TCCRnB

Edge

Detector

( From Prescaler )

clk

ATMEGA48 Datasheet(PDF) 140 Page - ATMEL Corporation

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