ATMEGA2561V ATMEL [ATMEL Corporation], ATMEGA2561V Datasheet - Page 192

• Manufacturer Part Number: ATMEGA2561V
• Description: 8-bit Microcontroller with 64K/128K/256K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

192
ATmega640/1280/1281/2560/2561
Table 90. Compare Output Mode, Phase Correct PWM Mode
Note:
• Bits 5:4 – COM2B1:0: Compare Match Output B Mode
These bits control the Output Compare pin (OC2B) behavior. If one or both of the
COM2B1:0 bits are set, the OC2B 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 OC2B pin must be set in order to enable the output driver.
When OC2B is connected to the pin, the function of the COM2B1:0 bits depends on the
WGM22:0 bit setting. Table 91 shows the COM2B1:0 bit functionality when the
WGM22:0 bits are set to a normal or CTC mode (non-PWM).
Table 91. Compare Output Mode, non-PWM Mode
Table 92 shows the COM2B1:0 bit functionality when the WGM22:0 bits are set to fast
PWM mode.
Table 92. Compare Output Mode, Fast PWM Mode
Note:
COM2A1
COM2B1
COM2B1
0
0
1
1
0
0
1
1
0
0
1
1
1. A special case occurs when OCR2A equals TOP and COM2A1 is set. In this case,
1. A special case occurs when OCR2B equals TOP and COM2B1 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 182 for more details.
the Compare Match is ignored, but the set or clear is done at BOTTOM. See “Fast
PWM Mode” on page 180 for more details.
COM2A0
COM2B0
COM2B0
0
1
0
1
0
1
0
1
0
1
0
1
Description
Normal port operation, OC2A disconnected.
WGM22 = 0: Normal Port Operation, OC2A Disconnected.
WGM22 = 1: Toggle OC2A on Compare Match.
Clear OC2A on Compare Match when up-counting. Set OC2A on
Compare Match when down-counting.
Set OC2A on Compare Match when up-counting. Clear OC2A on
Compare Match when down-counting.
Description
Normal port operation, OC2B disconnected.
Toggle OC2B on Compare Match
Clear OC2B on Compare Match
Set OC2B on Compare Match
Description
Normal port operation, OC2B disconnected.
Reserved
Clear OC2B on Compare Match, set OC2B at BOTTOM,
(non-inverting mode).
Set OC2B on Compare Match, clear OC2B at BOTTOM,
(inverting mode).
(1)
(1)
2549K–AVR–01/07