71
8126F–AVR–05/12
ATtiny13A
shows the COM0A[1:0] bit functionality when the WGM0[1:0] 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 Com-
pare Match is ignored, but the set or clear is done at TOP. See
for more details.
shows the COM0A[1:0] bit functionality when the WGM0[2:0] 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 Com-
pare Match is ignored, but the set or clear is done at TOP. See
• Bits 5:4 – COM0B[1:0]: Compare Match Output B Mode
These bits control the Output Compare pin (OC0B) behavior. If one or both of the COM0B[1:0]
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 corresponding 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 COM0B[1:0] bits depends on the
WGM0[2:0] bit setting.
shows the COM0B[1:0] bit functionality when the WGM0[2:0] bits are set
to a normal or CTC mode (non-PWM).
Table 11-3.
Compare Output Mode, Fast PWM Mode
COM0A1
COM0A0
Description
0
0
Normal port operation, OC0A disconnected.
0
1
WGM02 = 0: Normal Port Operation, OC0A Disconnected.
WGM02 = 1: Toggle OC0A on Compare Match.
1
0
Clear OC0A on Compare Match, set OC0A at TOP
1
1
Set OC0A on Compare Match, clear OC0A at TOP
Table 11-4.
Compare Output Mode, Phase Correct PWM Mode
COM0A1
COM0A0
Description
0
0
Normal port operation, OC0A disconnected.
0
1
WGM02 = 0: Normal Port Operation, OC0A Disconnected.
WGM02 = 1: Toggle OC0A on Compare Match.
1
0
Clear OC0A on Compare Match when up-counting. Set OC0A on
Compare Match when down-counting.
1
1
Set OC0A on Compare Match when up-counting. Clear OC0A on
Compare Match when down-counting.