Datasheet
112
8197C–AVR–05/11
ATtiny261A/461A/861A
Table 12-10 shows the COM1A[1:0] bit functionality when the PWM1A, WGM10 and WGM11
bits are set to Phase and Frequency Correct PWM Mode.
Table 12-11 shows the COM1A[1:0] bit functionality when the PWM1A, WGM10 and WGM11
bits are set to single-slope PWM6 Mode. In the PWM6 Mode the same Waveform Output
(OCW1A) is used for generating all waveforms and the Output Compare values OC1A and
OC1A
are connected on thw all OC1x and OC1x pins as described below.
Table 12-12 shows the COM1A[1:0] bit functionality when the PWM1A, WGM10 and WGM11
bits are set to dual-slope PWM6 Mode.I
Bits COM1A1 and COM1A0 are shadowed in TCCR1C. Writing to bits COM1A1 and COM1A0
will also change bits COM1A1S and COM1A0S in TCCR1C. Similary, changes written to bits
COM1A1S and COM1A0S in TCCR1C will show here. See “TCCR1C – Timer/Counter1 Control
Register C” on page 116.
Table 12-10. Compare Output Mode, Phase and Frequency Correct PWM Mode
COM1A[1:0] OCW1A Behaviour OC1A Pin OC1A Pin
00 Normal port operation. Disconnected Disconnected
01
Cleared on Compare Match when up-counting.
Set on Compare Match when down-counting.
Connected Connected
10
Cleared on Compare Match when up-counting.
Set on Compare Match when down-counting.
Connected Disconnected
11
Set on Compare Match when up-counting.
Cleared on Compare Match when down-counting.
Connected Disconnected
Table 12-11. Compare Output Mode, Single-Slope PWM6 Mode
COM1A[1:0] OCW1A Behaviour OC1x Pin OC1x Pin
00 Normal port operation. Disconnected Disconnected
01
Cleared on Compare Match.
Set when TCNT1 = 0x000.
OC1A OC1A
10
Cleared on Compare Match.
Set when TCNT1 = 0x000.
OC1A OC1A
11
Set on Compare Match.
Cleared when TCNT1 = 0x000.
OC1A OC1A
Table 12-12. Compare Output Mode, Dual-Slope PWM6 Mode
COM1A[1:0] OCW1A Behaviour OC1x Pin OC1x Pin
00 Normal port operation. Disconnected Disconnected
01
Cleared on Compare Match when up-counting.
Set on Compare Match when down-counting.
OC1A OC1A
10
Cleared on Compare Match when up-counting.
Set on Compare Match when down-counting.
OC1A OC1A
11
Set on Compare Match when up-counting.
Cleared on Compare Match when down-counting.
OC1A OC1A