16-bit
Timer/Counter1
The 16-bit Timer/Counter unit allows accurate program execution timing (event man-
agement), wave generation, and signal timing measurement. The main features are:
• 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)
Overview
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 Com-
pare 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 32. 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 “16-bit Timer/Counter Register Description”
on page 95.
74
ATmega8(L)
2486M–AVR–12/03
ATMEL [ ATMEL ]
