ATTINY15 ATMEL [ATMEL Corporation], ATTINY15 Datasheet - Page 29

• Manufacturer Part Number: ATTINY15
• Manufacturer: ATMEL [ATMEL Corporation]

The 8-bit Timer/Counter1
1187D–12/01
This module features a high-resolution and a high-accuracy usage with the lower pres-
caling opportunities. Timer/Counter1 can also be used as an accurate, high speed, 8-bit
Pulse Width Modulator using clock speeds up to 25.6 MHz. In this mode,
Timer/Counter1 and the output compare registers serve as a standalone PWM. Refer to
page 34 for a detailed description of this function. Similarly, the high-prescaling opportu-
nities make this unit useful for lower-speed functions or exact-timing functions with
infrequent actions.
Figure 21 shows the block diagram for Timer/Counter1.
Figure 21. Timer/Counter1 Block Diagram
The two status flags (overflow and compare match) are found in the Timer/Counter
Interrupt Flag Register (TIFR). Control signals are found in the Timer/Counter Control
Register (TCCR1). The interrupt enable/disable settings are found in the Timer/Counter
Interrupt Mask Register (TIMSK).
The Timer/Counter1 contains two Output Compare registers, OCR1A and OCR1B, as
the data source to be compared with the Timer/Counter1 contents. In normal mode the
Output Compare function is operational with OCR1A only, and the Output Compare
function includes optional clearing of the counter on compare match, and action on the
Output Compare Pin (PB1) (OC1A).
In PWM mode OCR1A provides the data value against which the Timer/Counter value is
compared. Upon compare match the PWM output is generated. In PWM mode The
Timer/Counter counts up to the value specified in output compare register OCR1B and
starts again from $00. This feature allows limiting the counter “full” value to a specified
8-BIT DATA BUS
COMPARE REGISTER A
TIMER/COUNTER1
8-BIT COMPARATOR
REGISTER (TIMSK)
TIMER INT. MASK
T/C1 OUTPUT
(TCNT1)
(OCR1A)
T/C1 OVER-
FLOW IRQ
T/C CLEAR
T/C1 A COMPARE
COMPARE REGISTER B
8-BIT COMPARATOR
MATCH IRQ
REGISTER (TIFR)
TIMER INT. FLAG
T/C1 OUTPUT
(OCR1B)
T/C1 OC1A PIN/
(PWM OUTPUT)
PORT PB1
T/C1 CONTROL
REGISTER 1 (TCCR1)
T/C CONTROL
LOGIC
ATtiny15L
SFIOR
CK
PCK
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