ATMEga64L ATMEL Corporation, ATMEga64L Datasheet - Page 104

• Manufacturer Part Number: ATMEga64L
• Description: 8-bit AVR Microcontroller with 64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL Corporation

Timer/Counter Register –
TCNT0
Output Compare Register –
OCR0
104
ATmega64(L)
• Bit 2:0 – CS02:0: Clock Select
The three Clock Select bits select the clock source to be used by the Timer/Counter, see
Table 56.
Table 56. Clock Select Bit Description
The Timer/Counter Register gives direct access, both for read and write operations, to
the Timer/Counter unit 8-bit counter. Writing to the TCNT0 Register blocks (removes)
the Compare Match on the following timer clock. Modifying the counter (TCNT0) while
the counter is running, introduces a risk of missing a Compare Match between TCNT0
and the OCR0 Register.
The Output Compare Register contains an 8-bit value that is continuously compared
with the counter value (TCNT0). A match can be used to generate an Output Compare
interrupt, or to generate a waveform output on the OC0 pin.
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
CS02
0
0
0
0
1
1
1
1
CS01
R/W
R/W
0
0
1
1
0
0
1
1
7
0
7
0
R/W
R/W
6
0
6
0
CS00
0
1
0
1
0
1
0
1
R/W
R/W
5
0
5
0
Description
No clock source (Timer/counter stopped)
clk
clk
clk
clk
clk
clk
clk
T0S
T0S
T0S
T0S
T0S
T
T
0
0
S
S
/256 (From prescaler)
/1024 (From prescaler)
/(No prescaling)
/8 (From prescaler)
/32 (From prescaler)
/64 (From prescaler)
/128 (From prescaler)
R/W
R/W
4
0
4
0
TCNT0[7:0]
OCR0[7:0]
R/W
R/W
3
0
3
0
R/W
R/W
2
0
2
0
R/W
R/W
1
0
1
0
R/W
R/W
0
0
0
0
2490G–AVR–03/04
TCNT0
OCR0