AT90PWM2 datasheet(100/365 Pages) ATMEL

100 / 365 page

100

AT90PWM2/3

4317B–AVR–02/05

Notes:

1. MAX

= 0xFF

2. BOTTOM = 0x00

Timer/Counter Control

• Bit 7 – FOC0A: Force Output Compare A

The FOC0A bit is only active when the WGM bits specify a non-PWM mode.

However, for ensuring compatibility with future devices, this bit must be set to zero when

TCCR0B is written when operating in PWM mode. When writing a logical one to the

FOC0A bit, an immediate Compare Match is forced on the Waveform Generation unit.

The OC0A output is changed according to its COM0A1:0 bits setting. Note that the

FOC0A bit is implemented as a strobe. Therefore it is the value present in the

COM0A1:0 bits that determines the effect of the forced compare.

A FOC0A strobe will not generate any interrupt, nor will it clear the timer in CTC mode

using OCR0A as TOP.

The FOC0A bit is always read as zero.

• Bit 6 – FOC0B: Force Output Compare B

The FOC0B bit is only active when the WGM bits specify a non-PWM mode.

However, for ensuring compatibility with future devices, this bit must be set to zero when

TCCR0B is written when operating in PWM mode. When writing a logical one to the

FOC0B bit, an immediate Compare Match is forced on the Waveform Generation unit.

The OC0B output is changed according to its COM0B1:0 bits setting. Note that the

FOC0B bit is implemented as a strobe. Therefore it is the value present in the

COM0B1:0 bits that determines the effect of the forced compare.

A FOC0B strobe will not generate any interrupt, nor will it clear the timer in CTC mode

using OCR0B as TOP.

The FOC0B bit is always read as zero.

• Bits 5:4 – Res: Reserved Bits

These bits are reserved bits in the AT90PWM2/3 and will always read as zero.

• Bit 3 – WGM02: Waveform Generation Mode

See the description in the “Timer/Counter Control Register A – TCCR0A” on page 97.

• Bits 2:0 – CS02:0: Clock Select

100

Reserved

–

PWM, Phase

Correct

OCRA

TOP

BOTTOM

110

Reserved

–

111

Fast PWM

OCRA

TOP

Table 44. Waveform Generation Mode Bit Description (Continued)

Mode

WGM02

WGM01

WGM00

Timer/Count

er Mode of

Operation

TOP

Update of

OCRx at

TOV Flag

Set on

(1)(2)

Bit

210

FOC0A

FOC0B

–

WGM02

CS02

CS01

CS00

TCCR0B

Read/Write

R/W

Initial Value

AT90PWM2 Datasheet(PDF) 100 Page - ATMEL Corporation

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