ATMEGA8L ATMEL [ATMEL Corporation], ATMEGA8L Datasheet - Page 70

• Manufacturer Part Number: ATMEGA8L
• Description: 8-bit AVR with 8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

8-bit Timer/Counter
Register Description
Timer/Counter Control
Register – TCCR0
Timer/Counter Register –
TCNT0
Timer/Counter Interrupt Mask
Register – TIMSK
70
ATmega8(L)
• Bit 2:0 – CS02:0: Clock Select
The three clock select bits select the clock source to be used by the Timer/Counter.
Table 34. Clock Select Bit Description
If external pin modes are used for the Timer/Counter0, transitions on the T0 pin will
clock the counter even if the pin is configured as an output. This feature allows software
control of the counting.
The Timer/Counter Register gives direct access, both for read and write operations, to
the Timer/Counter unit 8-bit counter.
• Bit 0 – TOIE0: Timer/Counter0 Overflow Interrupt Enable
When the TOIE0 bit is written to one, and the I-bit in the Status Register is set (one), the
Timer/Counter0 Overflow interrupt is enabled. The corresponding interrupt is executed if
an overflow in Timer/Counter0 occurs, i.e., when the TOV0 bit is set in the
Timer/Counter Interrupt Flag Register – TIFR.
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
CS02
0
0
0
0
1
1
1
1
CS01
0
0
1
1
0
0
1
1
OCIE2
R/W
R/W
R
7
–
0
7
0
7
0
CS00
0
1
0
1
0
1
0
1
TOIE2
R/W
R/W
R
6
–
0
6
0
6
0
Description
No clock source (Timer/Counter stopped).
clk
clk
clk
clk
clk
External clock source on T0 pin. Clock on falling edge.
External clock source on T0 pin. Clock on rising edge.
TICIE1
I/O
I/O
I/O
I/O
I/O
R/W
R/W
R
5
–
0
5
0
5
0
/(No prescaling)
/8 (From prescaler)
/64 (From prescaler)
/256 (From prescaler)
/1024 (From prescaler)
OCIE1A
R/W
R/W
R
4
–
0
4
0
4
0
TCNT0[7:0]
OCIE1B
R/W
R/W
R
3
–
0
3
0
3
0
TOIE1
CS02
R/W
R/W
R/W
2
0
2
0
2
0
CS01
R/W
R/W
R/W
1
0
1
0
1
–
0
TOIE0
CS00
R/W
R/W
R/W
0
0
0
0
0
0
2486M–AVR–12/03
TCCR0
TCNT0
TIMSK