attiny15l ATMEL Corporation, attiny15l Datasheet - Page 28

• Manufacturer Part Number: attiny15l
• Description: Attiny15l 8-bit Microcontroller With 1k Byte Flash
• Manufacturer: ATMEL Corporation

The Timer Counter 0 – TCNT0
The 8-bit Timer/Counter1
28
ATtiny15L
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.
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
$32
Read/Write
Initial Value
8-BIT DATA BUS
COMPARE REGISTER A
TIMER/COUNTER1
8-BIT COMPARATOR
REGISTER (TIMSK)
TIMER INT. MASK
T/C1 OUTPUT
(TCNT1)
(OCR1A)
MSB
R/W
7
0
T/C1 OVER-
FLOW IRQ
R/W
6
0
T/C CLEAR
R/W
5
0
T/C1 A COMPARE
COMPARE REGISTER B
8-BIT COMPARATOR
MATCH IRQ
REGISTER (TIFR)
TIMER INT. FLAG
T/C1 OUTPUT
(OCR1B)
R/W
4
0
R/W
T/C1 OC1A PIN/
(PWM OUTPUT)
3
0
PORT PB1
R/W
T/C1 CONTROL
REGISTER 1 (TCCR1)
2
0
T/C CONTROL
LOGIC
R/W
1
0
LSB
R/W
0
0
SFIOR
1187H–AVR–09/07
TCNT0
CK
PCK