Atmel ATmega328 User Manual

146
8271D–AVR–05/11
ATmega48A/PA/88A/PA/168A/PA/328/P
18. 8-bit Timer/Counter2 with PWM and Asynchronous Operation
18.1 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 32kHz Watch Crystal Independent of the I/O Clock
18.2 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 18-1. For the actual placement of
I/O pins, refer to ”Pinout ATmega48A/PA/88A/PA/168A/PA/328/P” 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 160.
The PRTIM2 bit in ”Minimizing Power Consumption” on page 43 must be written to zero to
enable Timer/Counter2 module.
Figure 18-1. 8-bit Timer/Counter Block Diagram
Clock Select
Timer/Counter
DATA BUS
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
Tn
Edge
Detector
( From Prescaler )
clk
Tn

Atmel ATmega328 Specifications

General

Brand	Atmel
Model	ATmega328
Category	Microcontrollers
Language	English