ATMEGA128L-8MC View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
'ATMEGA128L-8MC' PDF : 395 Pages View PDF
8-bit Timer/Counter2
with PWM
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
• External Event Counter
• 10-bit Clock Prescaler
• Overflow and Compare Match Interrupt Sources (TOV2 and OCF2)
Overview
A simplified block diagram of the 8-bit Timer/Counter is shown in Figure 61. 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 “8-bit Timer/Counter Register Description” on
page 158.
Figure 61. 8-Bit Timer/Counter Block Diagram
TCCRn
count
clear
direction
Control Logic
BOTTOM
TOP
Timer/Counter
TCNTn
= 0 = 0xFF
=
clkTn
Clock Select
Edge
Detector
TOVn
(Int.Req.)
Tn
( From Prescaler )
Waveform
Generation
OCn
(Int.Req.)
OCn
OCRn
Registers
The Timer/Counter (TCNT2) and Output Compare Register (OCR2) are 8-bit registers.
Interrupt request (abbreviated to Int.Req. in the figure) 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 by an external clock
source on the T2 pin. The Clock Select logic block controls which clock source and edge
the Timer/Counter uses to increment (or decrement) its value. The Timer/Counter is
146 ATmega128
2467O–AVR–10/06
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