AT90PWM2 datasheet(98/365 Pages) ATMEL

98 / 365 page

AT90PWM2/3

4317B–AVR–02/05

Table 39 shows the COM0A1:0 bit functionality when the WGM01:0 bits are set to fast

PWM mode.

Note:

1. A special case occurs when OCR0A equals TOP and COM0A1 is set. In this case,

the Compare Match is ignored, but the set or clear is done at TOP. See “Fast PWM

Mode” on page 93 for more details.

Table 40 shows the COM0A1:0 bit functionality when the WGM02:0 bits are set to

phase correct PWM mode.

Note:

1. A special case occurs when OCR0A equals TOP and COM0A1 is set. In this case,

the Compare Match is ignored, but the set or clear is done at TOP. See “Phase Cor-

rect PWM Mode” on page 119 for more details.

• Bits 5:4 – COM0B1:0: Compare Match Output B Mode

These bits control the Output Compare pin (OC0B) behavior. If one or both of the

COM0B1:0 bits are set, the OC0B output overrides the normal port functionality of the

I/O pin it is connected to. However, note that the Data Direction Register (DDR) bit cor-

responding to the OC0B pin must be set in order to enable the output driver.

When OC0B is connected to the pin, the function of the COM0B1:0 bits depends on the

WGM02:0 bit setting. Table 41 shows the COM0B1:0 bit functionality when the

WGM02:0 bits are set to a normal or CTC mode (non-PWM).

Table 39. Compare Output Mode, Fast PWM Mode(1)

COM0A1

COM0A0

Description

Normal port operation, OC0A disconnected.

WGM02 = 0: Normal Port Operation, OC0A Disconnected.

WGM02 = 1: Toggle OC0A on Compare Match.

Clear OC0A on Compare Match, set OC0A at TOP

Set OC0A on Compare Match, clear OC0A at TOP

Table 40. Compare Output Mode, Phase Correct PWM Mode(1)

COM0A1

COM0A0

Description

Normal port operation, OC0A disconnected.

WGM02 = 0: Normal Port Operation, OC0A Disconnected.

WGM02 = 1: Toggle OC0A on Compare Match.

Clear OC0A on Compare Match when up-counting. Set OC0A on

Compare Match when down-counting.

Set OC0A on Compare Match when up-counting. Clear OC0A on

Compare Match when down-counting.

Table 41. Compare Output Mode, non-PWM Mode

COM0B1

COM0B0

Description

Normal port operation, OC0B disconnected.

Toggle OC0B on Compare Match

Clear OC0B on Compare Match

Set OC0B on Compare Match

AT90PWM2 Datasheet(PDF) 98 Page - ATMEL Corporation

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