Datasheet

128
ATmega169A/PA/329A/PA/649A/P/3290A/PA/6490A/P [DATASHEET]
8284E–AVR–02/2013
Figure 16-12. Timer/Counter timing diagram, no prescaling.
Figure 16-13 shows the same timing data, but with the prescaler enabled.
Figure 16-13. Timer/Counter timing diagram, with prescaler (f
clk_I/O
/8).
16.11 Register description
16.11.1 TCCR1A – Timer/Counter1 Control Register A
• Bit 7:6 – COM1A1:0: Compare Output Mode for Unit A
• Bit 5:4 – COM1B1:0: Compare Output Mode for Unit B
The COM1A1:0 and COM1B1:0 control the Output Compare pins (OC1A and OC1B respectively) 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
TOVn (FPWM)
and ICFn (if used
as TOP)
OCRnx
(Update at TOP)
TCNTn
(CTC and FPWM)
TCNTn
(PC and PFC PWM)
TOP - 1 TOP TOP - 1 TOP - 2
Old OCRnx Value
New OCRnx Value
TOP - 1 TOP BOTTOM BOTTOM + 1
clk
Tn
(clk
I/O
/1)
clk
I/O
TOVn (FPWM)
and ICFn (if used
as TOP)
OCRnx
(Update at TOP)
TCNTn
(CTC and FPWM)
TCNTn
(PC and PFC PWM)
TOP - 1
TOP TOP - 1 TOP - 2
Old OCRnx Value New OCRnx Value
TOP - 1 TOP BOTTOM BOTTOM + 1
clk
I/O
clk
Tn
(clk
I/O
/8)
Bit 7 6 5 43210
(0x80)
COM1A1 COM1A0 COM1B1 COM1B0 – – WGM11 WGM10 TCCR1A
Read/Write R/W R/W R/W R/W R R R/W R/W
Initial Value0 0 0 0 0000