Datasheet

124
ATtiny828 [DATASHEET]
8371A–AVR–08/12
Table 39. Compare Output Mode, non-PWM
Table 40 shows COM1x[1:0] bit functionality when WGM1[3:0] bits are set to fast PWM mode.
Table 40. Compare Output Mode, Fast PWM
Note: A special case occurs when OCR1A/OCR1B equals TOP and COM1A1/COM1B1 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 112 for more
details.
Table 41 shows COM1x[1:0] bit functionality when WGM1[3:0] bits are set to phase correct or phase and frequency
correct PWM mode.
Table 41. Compare Output Mode, Phase Correct and Phase & Frequency Correct PWM
Note: A special case occurs when OCR1A/OCR1B equals TOP and COM1A1/COM1B1 is set. “Phase Correct PWM
Mode” on page 114 for more details.
COM1A1
COM1B1
COM1A0
COM1B0 Description
0 0 Normal port operation, OC1A/OC1B disconnected
0 1 Toggle OC1A/OC1B on Compare Match
1 0
Clear OC1A/OC1B on Compare Match
(Set output to low level)
1 1
Set OC1A/OC1B on Compare Match
(Set output to high level).
COM1A1
COM1B1
COM1A0
COM1B0 Description
0 0 Normal port operation, OC1A/OC1B disconnected
0 1
WGM13=0: Normal port operation, OC1A/OC1B disconnected
WGM13=1: Toggle OC1A on Compare Match, OC1B reserved
1 0
Clear OC1A/OC1B on Compare Match, set OC1A/OC1B at BOTTOM (non-
inverting mode)
1 1
Set OC1A/OC1B on Compare Match, clear OC1A/OC1B at BOTTOM
(inverting mode)
COM1A1
COM1B1
COM1A0
COM1B0 Description
0 0 Normal port operation, OC1A/OC1B disconnected
0 1
WGM13=0: Normal port operation, OC1A/OC1B disconnected
WGM13=1: Toggle OC1A on Compare Match, OC1B reserved
1 0
Clear OC1A/OC1B on Compare Match when up-counting
Set OC1A/OC1B on Compare Match when downcounting
1 1
Set OC1A/OC1B on Compare Match when up-counting
Clear OC1A/OC1B on Compare Match when downcounting