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ATtiny15L
1187H–AVR–09/07
The Timer Counter 0 – TCNT0
The Timer/Counter0 is implemented as an up-counter with read and write access. If the
Timer/Counter0 is written and a clock source is present, the Timer/Counter0 continues
counting in the timer clock cycle following the write operation.
The 8-bit Timer/Counter1 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 (PWM) 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
opportunities 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).
Bit 76543210
$32 MSB LSB TCNT0
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
8-BIT DATA BUS
TIMER INT. FLAG
REGISTER (TIFR)
TIMER/COUNTER1
(TCNT1)
8-BIT COMPARATOR
T/C1 OUTPUT T/C1 OUTPUT
COMPARE REGISTER A COMPARE REGISTER B
TIMER INT. MASK
REGISTER (TIMSK)
T/C CLEAR
T/C1 CONTROL
LOGIC
TOV1
OCF1A
OCF1A
TOV1
TOIE0
TOIE1
OCIE1A
CK
PCK
T/C1 OVER-
FLOW IRQ
T/C1 A COMPARE
MATCH IRQ
T/C CONTROL
REGISTER 1 (TCCR1)
CS12
COM1A1
PWM1
CS11
COM1A0
CS10
CS13
(OCR1A)
8-BIT COMPARATOR
(OCR1B)
SFIOR
TOV0
FOC1
PSR1
CTC1
T/C1 OC1A PIN/
PORT PB1
(PWM OUTPUT)
PSR0
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