AT90USB646 datasheet(115/456 Pages) ATMEL

115 / 456 page

115

7593L–AVR–09/12

AT90USB64/128

15. 16-bit Timer/Counter (Timer/Counter1 and Timer/Counter3)

The 16-bit Timer/Counter unit allows accurate program execution timing (event management),

wave generation, and signal timing measurement. The main features are:

• True 16-bit design (that is, allows 16-bit PWM)

• Three 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

• Ten independent interrupt sources (TOV1, OCF1A, OCF1B, OCF1C, ICF1, TOV3, OCF3A, OCF3B,

OCF3C, and ICF3)

15.1

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 Compare unit

channel. However, when using the register or bit defines in a program, the precise form must be

used, that is, TCNT1 for accessing Timer/Counter1 counter value and so on.

A simplified block diagram of the 16-bit Timer/Counter is shown in Figure 15-1 on page 116. For

the actual placement of I/O pins, see “Pinout Atmel AT90USB64/128-TQFP.” on page 3. 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 (Timer/Counter1 and

Timer/Counter3)” on page 115.

The Power Reduction Timer/Counter1 bit, PRTIM1, in “PRR0 – Power Reduction Register 0” on

page 54 must be written to zero to enable Timer/Counter1 module.

The Power Reduction Timer/Counter3 bit, PRTIM3, in “PRR1 – Power Reduction Register 1” on

page 55 must be written to zero to enable Timer/Counter3 module.

AT90USB646 Datasheet(PDF) 115 Page - ATMEL Corporation