ATmega328P datasheet(144/448 Pages) ATMEL

144 / 448 page

144

8161D–AVR–10/09

ATmega48PA/88PA/168PA/328P

17. 8-bit Timer/Counter2 with PWM and Asynchronous Operation

17.1

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

17.2

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 17-1. For the actual placement of

I/O pins, refer to ”Pinout ATmega48PA/88PA/168PA/328P” on page 2. CPU accessible I/O Reg-

isters, 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 158.

The PRTIM2 bit in ”Minimizing Power Consumption” on page 42 must be written to zero to

enable Timer/Counter2 module.

Figure 17-1. 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

ATmega328P Datasheet(PDF) 144 Page - ATMEL Corporation

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