ATMEGA644PV ATMEL [ATMEL Corporation], ATMEGA644PV Datasheet - Page 92

• Manufacturer Part Number: ATMEGA644PV
• Description: 8-bit Microcontroller with 16/32/64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

13. 8-bit Timer/Counter0 with PWM
13.1
13.2
13.2.1
92
Features
Overview
ATmega164P/324P/644P
Registers
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Timer/Counter0 is a general purpose 8-bit Timer/Counter module, with two independent Output
Compare Units, and with PWM support. It allows accurate program execution timing (event man-
agement) and wave generation.
A simplified block diagram of the 8-bit Timer/Counter is shown in
placement of I/O pins, see
ing I/O bits and I/O pins, are shown in bold. The device-specific I/O Register and bit locations
are listed in the
Figure 13-1. 8-bit Timer/Counter Block Diagram
The Timer/Counter (TCNT0) and Output Compare Registers (OCR0A and OCR0B) are 8-bit
registers. Interrupt request (abbreviated to Int.Req. in the figure) signals are all visible in the
Timer Interrupt Flag Register (TIFR0). All interrupts are individually masked with the Timer Inter-
rupt Mask Register (TIMSK0). TIFR0 and TIMSK0 are not shown in the figure.
The Timer/Counter can be clocked internally, via the prescaler, or by an external clock source on
the T0 pin. The Clock Select logic block controls which clock source and edge the Timer/Counter
Two Independent Output Compare Units
Double Buffered Output Compare Registers
Clear Timer on Compare Match (Auto Reload)
Glitch Free, Phase Correct Pulse Width Modulator (PWM)
Variable PWM Period
Frequency Generator
Three Independent Interrupt Sources (TOV0, OCF0A, and OCF0B)
”Register Description” on page
Timer/Counter
”Pin Configurations” on page
TCCRnA
OCRnA
TCNTn
OCRnB
=
=
Direction
Count
Clear
Control Logic
TOP
=
TCCRnB
103.
Value
BOTTOM
Fixed
TOP
clk
=
Tn
0
2. CPU accessible I/O Registers, includ-
OCnA
(Int.Req.)
OCnB
(Int.Req.)
TOVn
(Int.Req.)
Clock Select
Generation
Generation
( From Prescaler )
Waveform
Waveform
Detector
Edge
Figure
13-1. For the actual
OCnA
OCnB
Tn
8011D–AVR–02/07