2 tcnt0l - timer/counter0 register low byte, 3 tcnt0h - timer/counter0 register high byte, 4 ocr0a - timer/counter0 output compare register a – Rainbow Electronics ATtiny861_V User Manual
Page 85: 5 ocr0b - timer/counter0 output compare register b
85
2588B–AVR–11/06
ATtiny261/461/861
Normal mode (counter) and Clear Timer on Compare Match (CTC) mode (see
14.10.2
TCNT0L – Timer/Counter0 Register Low Byte
The Timer/Counter0 Register Low Byte, TCNT0L, gives direct access, both for read and write
operations, to the Timer/Counter unit 8-bit counter. Writing to the TCNT0L Register blocks (dis-
ables) the Compare Match on the following timer clock. Modifying the counter (TCNT0L) while
the counter is running, introduces a risk of missing a Compare Match between TCNT0L and the
OCR0x Registers. In 16-bit mode the TCNT0L register contains the lower part of the 16-bit
Timer/Counter0 Register.
14.10.3
TCNT0H – Timer/Counter0 Register High Byte
When 16-bit mode is selected (the TCW0 bit is set to one) the Timer/Counter Register TCNT0H
combined to the Timer/Counter Register TCNT0L gives direct access, both for read and write
operations, to the Timer/Counter unit 16-bit counter. To ensure that both the high and low bytes
are read and written simultaneously when the CPU accesses these registers, the access is per-
formed using an 8-bit temporary high byte register (TEMP). This temporary register is shared by
all the other 16-bit registers. See
”Accessing Registers in 16-bit Mode” on page 80
14.10.4
OCR0A – Timer/Counter0 Output Compare Register A
The Output Compare Register A contains an 8-bit value that is continuously compared with the
counter value (TCNT0L). A match can be used to generate an Output Compare interrupt.
In 16-bit mode the OCR0A register contains the low byte of the 16-bit Output Compare Register.
To ensure that both the high and the low bytes are written simultaneously when the CPU writes
to these registers, the access is performed using an 8-bit temporary high byte register (TEMP).
This temporary register is shared by all the other 16-bit registers. See
.
14.10.5
OCR0B – Timer/Counter0 Output Compare Register B
The Output Compare Register B contains an 8-bit value that is continuously compared with the
counter value (TCNT0L in 8-bit mode and TCNTH in 16-bit mode). A match can be used to gen-
erate an Output Compare interrupt.
Bit
7
6
5
4
3
2
1
0
0x32 (0x52)
TCNT0L[7:0]
TCNT0L
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
0x14 (0x34)
TCNT0H[7:0]
TCNT0H
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
0x13 (0x33)
OCR0A[7:0]
OCR0A
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
0x12 (0x32)
OCR0B[7:0]
OCR0B
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0