ATmega325P datasheet(135/364 Pages) ATMEL

135 / 364 page

135

8023F–AVR–07/09

ATmega325P/3250P

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

16.1

Features

• Single Compare Unit 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 and OCF2A)

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

16.2

Overview

Timer/Counter2 is a general purpose, single compare unit, 8-bit Timer/Counter module. A simpli-

fied 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 ATmega3250P” 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 149.

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

Timer/Counter

TCNTn

Waveform

Generation

OCnx

= 0

Control Logic

= 0xFF

TOP

BOTTOM

count

clear

direction

TOVn

(Int.Req.)

OCnx

(Int.Req.)

Synchronization Unit

OCRnx

TCCRnx

ASSRn

Status flags

clk

I/O

clk

ASY

Synchronized Status flags

asynchronous mode

select (ASn)

TOSC1

T/C

Oscillator

TOSC2

Prescaler

clk

I/O

ATmega325P Datasheet(PDF) 135 Page - ATMEL Corporation

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