Rainbow Electronics ATmega64M1 - Manual (Page 86)

86
8209A–AVR–08/09
ATmega16M1/32M1/64M1
15. 8-bit Timer/Counter0 with PWM
15.1 Features
• 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)
15.2 Overview
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 Figure 15-1 . For the actual
placement of I/O pins, refer to “Pin Descriptions” on page 7 . 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
“Register Description” on page 97 .
The PRTIM0 bit in “Power Reduction Register” on page 39 must be written to zero to enable
Timer/Counter0 module.
Figure 15-1. 8-bit Timer/Counter Block Diagram
Timer/Counter
D
ATA
B
U
S
=
TCNTn
Waveform
Generation
OCnA
Control Logic
count
clear
direction
TOVn
(Int.Req.)
OCRnx
TCCRnA
Clock Select
Tn
Edge
Detector
( From Prescaler )
clk
Tn
OCnA
(Int.Req.)
=
OCRnx
Waveform
Generation
OCnB
OCnB
(Int.Req.)
TCCRnB
=
Fixed
TOP
Values
= 0
TOP BOTTOM