ATMEGA8A_1 Datasheet, PDF (78/307 Pages) ATMEL Corporation – 8-bit with 8K Bytes In-System Programmable Flash

ATmega8A
16. 16-bit Timer/Counter1
16.1 Features
16.2 Overview
• 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)
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 sec-
tion 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 Figure 16-1. 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 loca-
tions are listed in the “Register Description” on page 99.
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