ATMEGA649 datasheet(127/375 Pages) ATMEL

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ATmega329/3290/649/6490

2552H–AVR–11/06

Table 62 shows the COM1x1:0 bit functionality when the WGM13:0 bits are set to the

fast PWM mode.

Note:

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

set. In this case the compare match is ignored, but the set or clear is done at BOT-

TOM. See “Fast PWM Mode” on page 118. for more details.

Table 63 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 120. 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 waveform generation to be used, see Table 64. Modes of operation sup-

ported 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 62. Compare Output Mode, Fast PWM

(1)

COM1A1/COM1B1

COM1A0/COM1B0

Description

Normal port operation, OC1A/OC1B

disconnected.

WGM13:0 = 14 or 15: 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, set

OC1A/OC1B at BOTTOM (non-inverting mode).

Set OC1A/OC1B on Compare Match, clear

OC1A/OC1B at BOTTOM (inverting mode).

Table 63. 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 = 9 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 counting down.

Set OC1A/OC1B on Compare Match when up-

counting. Clear OC1A/OC1B on Compare Match

when counting down.

ATMEGA649 Datasheet(PDF) 127 Page - ATMEL Corporation

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