![](http://datasheet.mmic.net.cn/90000/MQ83C154DXXX-12-883R_datasheet_2377128/MQ83C154DXXX-12-883R_117.png)
117
2588F–AVR–06/2013
ATtiny261/461/861
12.12.3
TCCR1C – Timer/Counter1 Control Register C
Bits 7,6 – COM1A1S, COM1A0S: Comparator A Output Mode, Shadow Bits 1 and 0
These are shadow bits of COM1A1 and COM1A0 in TCCR1A. Writing to bits COM1A1S and
COM1A0S will also change bits COM1A1 and COM1A0 in TCCR1A. Similary, changes written
to bits COM1A1 and COM1A0 in TCCR1A will show here.
Bits 5,4 – COM1B1S, COM1B0S: Comparator B Output Mode, Shadow Bits 1 and 0
These are shadow bits of COM1B1 and COM1B0 in TCCR1A. Writing to bits COM1B1S and
COM1B0S will also change bits COM1B1 and COM1B0 in TCCR1A. Similary, changes written
to bits COM1B1 and COM1B0 in TCCR1A will show here.
Bits 3,2 – COM1D1, COM1D0: Comparator D Output Mode, Bits 1 and 0
These bits control the behaviour of the Waveform Output (OCW1D) and the connection of the
Output Compare pin (OC1D). If one or both of the COM1D1:0 bits are set, the OC1D output
overrides the normal port functionality of the I/O pin it is connected to. The complementary
OC1D output is connected only in PWM modes when the COM1D1:0 bits are set to “01”. Note
that the Data Direction Register (DDR) bit corresponding to the OC1D pin must be set in order to
enable the output driver.
The function of the COM1D1:0 bits depends on the PWM1D and WGM11:10 bit settings.
Table12-18 shows the COM1D1:0 bit functionality when the PWM1D bit is set to a Normal Mode (non-
PWM).
Table 12-19 shows the COM1D1:0 bit functionality when the PWM1D and WGM11:10 bits are
set to Fast PWM Mode.
Bit
76543210
COM1A1
S
COM1A0
S
COM1B1
S
COM1B0
S
COM1D1
COM1D0
FOC1D
PWM1D
TCCR1C
Read/Write
R/W
Initial value
00000000
Table 12-18. Compare Output Mode, Normal Mode (non-PWM)
COM1D1:0
OCW1D Behaviour
OC1D Pin
00
Normal port operation.
Disconnected
01
Toggle on Compare Match.
Connected
Disconnected
10
Clear on Compare Match.
Connected
Disconnected
11
Set on Compare Match.
Connected
Disconnected
Table 12-19. Compare Output Mode, Fast PWM Mode
COM1D1:0
OCW1D Behaviour
OC1D Pin
00
Normal port operation.
Disconnected
01
Cleared on Compare Match. Set when TCNT1=0x000.
Connected
10
Cleared on Compare Match. Set when TCNT1=0x000.
Connected
Disconnected
11
Set on Compare Match. Cleared when TCNT1=0x000.
Connected
Disconnected