ATmega88 datasheet(128/340 Pages) ATMEL

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7530H–AVR–02/09

ATmega48/88/168 Automotive

Table 14-3 shows the COM1x1:0 bit functionality when the WGM13:0 bits are set to the phase

correct or the phase and frequency correct, PWM mode.

Note:

1. A special case occurs when OCR1A/OCR1B equals TOP and COM1A1/COM1B1 is set. See

“Phase Correct PWM Mode” on page 121. for more details.

• Bit 1:0 – WGM11:0: Waveform Generation Mode

Combined with the WGM13:2 bits found in the TCCR1B Register, these bits control the counting

sequence of the counter, the source for maximum (TOP) counter value, and what type of wave-

form generation to be used, see Table 14-4. Modes of operation supported by the Timer/Counter

unit are: Normal mode (counter), Clear Timer on Compare match (CTC) mode, and three types

of Pulse Width Modulation (PWM) modes. (See “Modes of Operation” on page 117.).

Table 14-3.

Compare Output Mode, Phase Correct and Phase and Frequency Correct

PWM

(1)

COM1A1/COM1B1

COM1A0/COM1B0

Description

Normal port operation, OC1A/OC1B disconnected.

WGM13:0 = 8, 9, 10 or 11: Toggle OC1A on Compare

Match, OC1B disconnected (normal port operation).

For all other WGM1 settings, normal port operation,

OC1A/OC1B disconnected.

Clear OC1A/OC1B on Compare Match when

up-counting. Set OC1A/OC1B on Compare Match

when downcounting.

Set OC1A/OC1B on Compare Match when

up-counting. Clear OC1A/OC1B on Compare Match

when downcounting.

ATmega88 Datasheet(PDF) 128 Page - ATMEL Corporation