ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 92

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

14.2.1
92
Atmel ATtiny24/44/84 [Preliminary]
Registers
Figure 14-1. 16-bit Timer/Counter Block Diagram
Note:
The timer/counter (TCNT1), output compare registers (OCR1A/B), and input capture register
(ICR1) are all 16-bit registers. Special procedures must be followed when accessing the 16-bit
registers. These procedures are described in the section
94. The timer/counter control registers (TCCR1A/B) are 8-bit registers, and have no CPU
access restrictions. Interrupt request (abbreviated to Int.Req. in the figure) signals are all visi-
ble in the timer interrupt flag register (TIFR). All interrupts are individually masked with the
timer interrupt mask register (TIMSK). TIFR and TIMSK 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. See
T
1
).
Figure 1-1 on page 2
Timer/Counter
TCCRnA
OCRnA
OCRnB
TCNTn
ICRn
=
=
Direction
Count
Clear
for Timer/Counter1 pin placement and description.
Control Logic
TOP
=
TCCRnB
Values
BOTTOM
Fixed
TOP
ICFn (Int.Req.)
(1)
clk
Detector
Edge
=
Tn
0
“Accessing 16-bit Registers” on page
OCnA
(Int.Req.)
OCnB
(Int.Req.)
TOVn
(Int.Req.)
Clock Select
Generation
Generation
( From Prescaler )
Waveform
Waveform
Canceler
Detector
Noise
Edge
Comparator Ouput )
( From Analog
7701E–AVR–02/11
OCnA
OCnB
ICPn
Tn