Datasheet

154
8011O–AVR–07/10
ATmega164P/324P/644P
When OC2B is connected to the pin, the function of the COM2B1:0 bits depends on the
WGM22:0 bit setting. Table 14-5 shows the COM2B1:0 bit functionality when the WGM22:0 bits
are set to a normal or CTC mode (non-PWM).
Table 14-6 shows the COM2B1:0 bit functionality when the WGM22:0 bits are set to fast PWM
mode.
Note: 1. A special case occurs when OCR2B equals TOP and COM2B1 is set. In this case, the Com-
pare Match is ignored, but the set or clear is done at BOTTOM. See ”Fast PWM Mode” on
page 145 for more details.
Table 14-7 shows the COM2B1:0 bit functionality when the WGM22:0 bits are set to phase cor-
rect PWM mode.
Note: 1. A special case occurs when OCR2B equals TOP and COM2B1 is set. In this case, the Com-
pare Match is ignored, but the set or clear is done at TOP. See ”Phase Correct PWM Mode” on
page 147 for more details.
• Bits 3:2 – Res: Reserved Bits
These bits are reserved bits in the ATmega164P/324P/644P and will always read as zero.
Table 14-5. Compare Output Mode, non-PWM Mode
COM2B1 COM2B0 Description
0 0 Normal port operation, OC2B disconnected.
0 1 Toggle OC2B on Compare Match
1 0 Clear OC2B on Compare Match
1 1 Set OC2B on Compare Match
Table 14-6. Compare Output Mode, Fast PWM Mode
(1)
COM2B1 COM2B0 Description
0 0 Normal port operation, OC2B disconnected.
01Reserved
10
Clear OC2B on Compare Match, set OC2B at BOTTOM,
(non-inverting mode).
11
Set OC2B on Compare Match, clear OC2B at BOTTOM,
(inverting mode).
Table 14-7. Compare Output Mode, Phase Correct PWM Mode
(1)
COM2B1 COM2B0 Description
0 0 Normal port operation, OC2B disconnected.
01Reserved
10
Clear OC2B on Compare Match when up-counting. Set OC2B on
Compare Match when down-counting.
11
Set OC2B on Compare Match when up-counting. Clear OC2B on
Compare Match when down-counting.