88
Atmel ATmega16/32/64/M1/C1 [DATASHEET]
7647K–AVR–12/13
Table 12-6 shows the COM0B1:0 bit functionality when the WGM02:0 bits are set to fast PWM mode.
Note:
1.
A special case occurs when OCR0B equals TOP and COM0B1 is set. In this case, the compare match is ignored,
Table 12-7 shows the COM0B1:0 bit functionality when the WGM02:0 bits are set to phase correct PWM mode.
Note:
1.
A special case occurs when OCR0B equals TOP and COM0B1 is set. In this case, the compare match is ignored,
Bits 3, 2 – Res: Reserved Bits
These bits are reserved bits in the ATmega16/32/64/M1/C1 and will always read as zero.
Bits 1:0 – WGM01:0: Waveform Generation Mode
Combined with the WGM02 bit found in the TCCR0B 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 12-8. Modes of
operation supported by the Timer/Counter unit are: Normal mode (counter), clear timer on compare match (CTC) mode, and
Notes: 1.
MAX
= 0xFF
2.
BOTTOM = 0x00
Table 12-6. Compare Output Mode, Fast PWM Mode(1) COM0B1
COM0B0
Description
0
Normal port operation, OC0B disconnected.
0
1
Reserved
1
0
Clear OC0B on compare match, set OC0B at TOP
1
Set OC0B on compare match, clear OC0B at TOP
Table 12-7. Compare Output Mode, Phase Correct PWM Mode(1)
COM0B1
COM0B0
Description
0
Normal port operation, OC0B disconnected.
0
1
Reserved
1
0
Clear OC0B on compare match when up-counting. Set OC0B on compare match when
down-counting.
1
Set OC0B on compare match when up-counting. Clear OC0B on compare match when
down-counting.
Table 12-8. Waveform Generation Mode Bit Description
Mode
WGM02
WGM01
WGM00
Timer/Counter
Mode of Operation
TOP
Update of
OCRx at
TOV Flag
0
Normal
0xFF
Immediate
MAX
1
0
1
PWM, phase correct
0xFF
TOP
BOTTOM
2
0
1
0
CTC
OCRA
Immediate
MAX
3
0
1
Fast PWM
0xFF
TOP
MAX
4
1
0
Reserved
–
5
1
0
1
PWM, phase correct
OCRA
TOP
BOTTOM
6
1
0
Reserved
–
7
1
Fast PWM
OCRA
TOP