ATmega328P datasheet(136/345 Pages) ATMEL

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136

7810A–AVR–11/09

ATmega328P [Preliminary]

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” 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 “Reg-

ister Description” on page 150.

The PRTIM2 bit in “Minimizing Power Consumption” on page 40 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) 136 Page - ATMEL Corporation

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