
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
isters, including I/O bits and I/O pins, are shown in bold. The device-specific I/O Register and bit
enable Timer/Counter2 module.
Figure 17-1. 8-bit Timer/Counter Block Diagram
Clock Select
Timer/Counter
DA
T
A
B
U
S
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