ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 112

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

16.2.1
112
Atmel ATmega48PA/88PA/168PA [Preliminary]
Registers
Figure 16-1. 16-bit Timer/Counter Block Diagram
Note:
The Timer/Counter (TCNT1), Output Compare Registers (OCR1A/B), and Input Capture Reg-
ister (ICR1) are all 16-bit registers. Special procedures must be followed when accessing the
16-bit registers. These procedures are described in the section
on page
no CPU access restrictions. Interrupt requests (abbreviated to Int.Req. in the figure) signals
are all visible in the Timer Interrupt Flag Register (TIFR1). All interrupts are individually
masked with the Timer Interrupt Mask Register (TIMSK1). TIFR1 and TIMSK1 are not shown
in the figure.
The Timer/Counter can be clocked internally, via the prescaler, or by an external clock source
on the T1 pin. The Clock Select logic block controls which clock source and edge the
Timer/Counter uses to increment (or decrement) its value. The Timer/Counter is inactive when
no clock source is selected. The output from the Clock Select logic is referred to as the timer
clock (clk
1. Refer to
113. The Timer/Counter Control Registers (TCCR1A/B) are 8-bit registers and have
T
1
).
Timer/Counter1 pin placement and description.
Timer/Counter
Figure 1-1 on page
TCCRnA
OCRnB
OCRnA
TCNTn
ICRn
=
=
Direction
Count
Clear
2,
Control Logic
Table 14-3 on page 81
TOP
=
TCCRnB
Values
BOTTOM
Fixed
TOP
ICFn (Int.Req.)
clk
Detector
(1)
Edge
=
Tn
0
and
OCnA
(Int.Req.)
OCnB
(Int.Req.)
Table 14-9 on page 88
TOVn
(Int.Req.)
Clock Select
“Accessing 16-bit Registers”
Generation
Generation
( From Prescaler )
Waveform
Waveform
Canceler
Detector
Noise
Edge
Comparator Ouput )
( From Analog
9223B–AVR–09/11
OCnA
OCnB
ICPn
for
Tn