attiny25v ATMEL Corporation, attiny25v Datasheet - Page 87

• Manufacturer Part Number: attiny25v
• Description: Microcontroller With 2/4/8k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

2586K–AVR–01/08
Timer/Counter1 and the output compare registers serve as dual stand-alone PWMs with non-
overlapping non-inverted and inverted outputs. Refer to
this function. Similarly, the high prescaling opportunities make this unit useful for lower speed
functions or exact timing functions with infrequent actions.
Figure 12-2. Timer/Counter 1 Synchronization Register Block Diagram.
Timer/Counter1 and the prescaler allow running the CPU from any clock source while the pres-
caler is operating on the fast 64 MHz (or 32 MHz in Low Speed Mode) PCK clock in the
asynchronous mode.
Note that the system clock frequency must be lower than one third of the PCK frequency. The
synchronization mechanism of the asynchronous Timer/Counter1 needs at least two edges of
the PCK when the system clock is high. If the frequency of the system clock is too high, it is a
risk that data or control values are lost.
The following
PCKE
CK
PCK
SYNC
MODE
ASYNC
MODE
IO-registers
OCR1B
OCF1A
OCR1A
OCR1C
TCCR1
GTCCR
TCNT1
OCF1B
TOV1
Figure 12-3
1..2 PCK Delay
1/2 CK Delay
shows the block diagram for Timer/Counter1.
S
A
Input synchronization
registers
OCR1A_SI
OCR1B_SI
OCR1C_SI
TCCR1_SI
GTCCR_SI
TCNT1_SI
OCF1A_SI
OCF1B_SI
TOV1_SI
1 PCK Delay
1 CK Delay
S
A
8-BIT DATABUS
Timer/Counter1
TCNT1
page 89
~1 CK Delay
1 CK Delay
for a detailed description on
ATtiny25/45/85
Output synchronization
registers
TCNT_SO
OCF1A_SO
OCF1B_SO
TOV1_SO
1/2 CK Delay
No Delay
TCNT1
OCF1A
OCF1B
TOV1
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