Datasheet

99
ATmega8A [DATASHEET]
8159E–AVR–02/2013
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 and OCF2)
• 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 “Pin Configurations”
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 112.
Figure 18-1. 8-bit Timer/Counter Block Diagram
Timer/Counter
DATA B U S
=
TCNTn
Waveform
Generation
OCn
= 0
Control Logic
= 0xFF
TOPBOTTOM
count
clear
direction
TOVn
(Int. Req.)
OCn
(Int. Req.)
Synchronization Unit
OCRn
TCCRn
ASSRn
Status Flags
clk
I/O
clk
ASY
Synchronized Status Flags
asynchronous Mode
Select (ASn)
TOSC1
T/C
Oscillator
TOSC2
Prescaler
clk
Tn
clk
I/O