ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 133

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

16.11 Register Description
16.11.1
9223B–AVR–09/11
TCCR1A – Timer/Counter1 Control Register A
• Bit 7:6 – COM1A1:0: Compare Output Mode for Channel A
• Bit 5:4 – COM1B1:0: Compare Output Mode for Channel B
The COM1A1:0 and COM1B1:0 control the Output Compare pins (OC1A and OC1B respec-
tively) behavior. If one or both of the COM1A1:0 bits are written to one, the OC1A output
overrides the normal port functionality of the I/O pin it is connected to. If one or both of the
COM1B1:0 bit are written to one, the OC1B output overrides the normal port functionality of
the I/O pin it is connected to. However, note that the Data Direction Register (DDR) bit corre-
sponding to the OC1A or OC1B pin must be set in order to enable the output driver.
When the OC1A or OC1B is connected to the pin, the function of the COM1x1:0 bits is depen-
dent of the WGM13:0 bits setting.
WGM13:0 bits are set to a Normal or a CTC mode (non-PWM).
Table 16-1.
Table 16-2
PWM mode.
Table 16-2.
Note:
Bit
(0x80)
Read/Write
Initial Value
COM1A1/COM1B1
COM1A1/COM1B1
Atmel ATmega48PA/88PA/168PA [Preliminary]
1. A special case occurs when OCR1A/OCR1B equals TOP and COM1A1/COM1B1 is set. In
0
0
1
1
0
0
1
1
shows the COM1x1:0 bit functionality when the WGM13:0 bits are set to the fast
this case the compare match is ignored, but the set or clear is done at BOTTOM.
PWM Mode” on page 125.
COM1A1
Compare Output Mode, non-PWM
Compare Output Mode, Fast PWM
R/W
7
0
COM1A0
COM1A0/COM1B0
COM1A0/COM1B0
R/W
6
0
0
1
0
1
0
1
0
1
COM1B1
R/W
Table 16-1
5
0
for more details.
COM1B0
R/W
Description
Normal port operation, OC1A/OC1B disconnected.
Toggle OC1A/OC1B on Compare Match.
Clear OC1A/OC1B on Compare Match (Set output to
low level).
Set OC1A/OC1B on Compare Match (Set output to
high level).
Description
Normal port operation, OC1A/OC1B disconnected.
WGM13:0 = 14 or 15: Toggle OC1A on Compare
Match, OC1B disconnected (normal port operation).
For all other WGM1 settings, normal port operation,
OC1A/OC1B disconnected.
Clear OC1A/OC1B on Compare Match, set
OC1A/OC1B at BOTTOM (non-inverting mode)
Set OC1A/OC1B on Compare Match, clear
OC1A/OC1B at BOTTOM (inverting mode)
4
0
shows the COM1x1:0 bit functionality when the
(1)
R
3
0
–
R
2
–
0
WGM11
R/W
1
0
WGM10
R/W
0
0
See “Fast
TCCR1A
133