ATMEGA128A_1 Datasheet, PDF (93/386 Pages) ATMEL Corporation – Write/Erase cycles: 10,000 Flash/100,000 EEPROM

ATmega128A
14. 8-bit Timer/Counter0 with PWM and Asynchronous Operation
14.1 Features
14.2 Overview
• 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 (TOV0 and OCF0)
• Allows Clocking from External 32 kHz Watch Crystal Independent of the I/O Clock
Timer/Counter0 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 14-1. 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 106.
Figure 14-1. 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
Status flags
Synchronized Status flags
Synchronization Unit
ASSRn
asynchronous mode
select (ASn)
clk _I/O
clk _ASY
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