
143
8272E–AVR–04/2013
ATmega164A/PA/324A/PA/644A/PA/1284/P
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 32kHz 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 16-12.. For the actual
ing I/O bits and I/O pins, are shown in bold. The device-specific I/O Register and bit locations
page 48 must be written to zero to enable Timer/Counter2 module.
 Figure 17-1. 8-bit Timer/Counter block diagram.
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
clk
Tn
ASSRn
Synchronization Unit
Prescaler
T/C
Oscillator
clk
I/O
clk
ASY
asynchronous mode
select (ASn)
Synchronized Status flags
TOSC1
TOSC2
Status flags
clk
I/O