Datasheet

Figure 20-1. 16-bit Timer/Counter Block Diagram
Clock Select
Timer/Counter
DATA BUS
OCRnA
OCRnB
ICRn
=
=
TCNTn
Waveform
Generation
Waveform
Generation
OCnA
OCnB
Noise
Canceler
ICPn
=
Fixed
TOP
Values
Edge
Detector
Control Logic
= 0
TOP BOTTOM
Count
Clear
Direction
TOVn
(Int.Req.)
OCnA
(Int.Req.)
OCnB
(Int.Req.)
ICFn (Int.Req.)
TCCRnA TCCRnB
( From Analog
Comparator Ouput )
Tn
Edge
Detector
( From Prescaler )
clk
Tn
See the related links for actual pin placement.
20.4 Definitions
Many register and bit references in this section are written in general form:
• n=1 represents the timer/counter number
• x=A,B represents the output compare unit A or B
However, when using the register or bit definitions in a program, the precise form must be used, i.e.,
TCNT1 for accessing timer/counter1 counter value.
The following definitions are used throughout the section:
ATmega48PA/88PA/168PA
16-bit Timer/Counter1 (TC1) with PWM
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Datasheet Complete
DS40002011A-page 162