ATMEGA8_14 Datasheet, PDF (102/331 Pages) ATMEL Corporation – High-performance, Low-power Atmel

ATmega8(L)
8-bit
Timer/Counter2
with PWM and
Asynchronous
Operation
Timer/Counter2 is a general purpose, single channel, 8-bit Timer/Counter module. The main
features are:
• 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
Overview
A simplified block diagram of the 8-bit Timer/Counter is shown in Figure 45. For the actual place-
ment 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 loca-
tions are listed in the “8-bit Timer/Counter Register Description” on page 114.
Figure 45. 8-bit Timer/Counter Block Diagram
TCCRn
count
clear
direction
Control Logic
BOTTOM
TOP
Timer/Counter
TCNTn
= 0 = 0xFF
=
clk_Tn
Prescaler
OCn
(Int. Req.)
Waveform
Generation
TOVn
(Int. Req.)
T/C
Oscillator
TOSC1
TOSC2
clk_I/O
OCn
OCRn
2486AA–AVR–02/2013
Synchronized Status Flags
Synchronization Unit
Status Flags
ASSRn
asynchronous Mode
Select (ASn)
clk_I/O
clk_ASY
102