ATMEga64L ATMEL Corporation, ATMEga64L Datasheet - Page 91

• Manufacturer Part Number: ATMEga64L
• Description: 8-bit AVR Microcontroller with 64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL Corporation

8-bit Timer/Counter0
with PWM and
Asynchronous
Operation
Overview
Registers
2490G–AVR–03/04
Timer/Counter0 is a general purpose, single-channel, 8-bit Timer/Counter module. The
main features are:
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A simplified block diagram of the 8-bit Timer/Counter is shown in Figure 34. For the
actual placement of I/O pins, refer to “Pin Configuration” 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 “8-bit Timer/Counter Register Description” on
page 102.
Figure 34. 8-bit Timer/Counter Block Diagram
The Timer/Counter (TCNT0) and Output Compare Register (OCR0) are 8-bit registers.
Interrupt request (shorten as Int.Req.) signals are all visible in the Timer Interrupt Flag
Register (TIFR). All interrupts are individually masked with the Timer Interrupt Mask
Register (TIMSK). TIFR and TIMSK are not shown in the figure since these registers are
shared by other timer units.
The Timer/Counter can be clocked internally, via the prescaler, or asynchronously
clocked from the TOSC1/2 pins, as detailed later in this section. The asynchronous
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
Status Flags
Timer/Counter
TCNTn
OCRn
=
ASSRn
direction
count
clear
BOTTOM
Synchronized Status Flags
= 0
Control Logic
=
TCCRn
TOP
Asynchronous Mode
0xFF
Select (ASn)
clk
Tn
Synchronization Unit
OCn
(Int. Req.)
Generation
Prescaler
Waveform
ATmega64(L)
Oscillator
T/C
clk
TOVn
(Int. Req.)
clk
OCn
clk
ASY
I/O
I/O
TOSC1
TOSC2
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