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8025I–AVR–02/09
ATmega48P/88P/168P/328P
13. 16-bit Timer/Counter1 with PWM
13.1
Features
•
True 16-bit Design (i.e., Allows 16-bit PWM)
•
Two independent Output Compare Units
•
Double Buffered Output Compare Registers
•
One Input Capture Unit
•
Input Capture Noise Canceler
•
Clear Timer on Compare Match (Auto Reload)
•
Glitch-free, Phase Correct Pulse Width Modulator (PWM)
•
Variable PWM Period
•
Frequency Generator
•
External Event Counter
•
Four independent interrupt Sources (TOV1, OCF1A, OCF1B, and ICF1)
13.2
Overview
The 16-bit Timer/Counter unit allows accurate program execution timing (event management),
wave generation, and signal timing measurement.
Most register and bit references in this section are written in general form. A lower case “n”
replaces the Timer/Counter number, and a lower case “x” replaces the Output Compare unit
channel. However, when using the register or bit defines in a program, the precise form must be
used, i.e., TCNT1 for accessing Timer/Counter1 counter value and so on.
A simplified block diagram of the 16-bit Timer/Counter is shown in
placement of I/O pins, refer to
”Pinout ATmega48P/88P/168P/328P” 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 134
.
The PRTIM1 bit in
”PRR – Power Reduction Register” on page 45
must be written to zero to
enable Timer/Counter1 module.