39
ATmega103(L)
0945G–09/01
• Bits 2, 1, 0 – CS02, CS01, CS00/CS22, CS21, CS20: Clock Select Bits 2, 1 and 0
The Clock Select2 bits 2, 1 and 0 define the prescaling source of the Timer/Counter.
The Stop condition provides a Timer Enable/Disable function. The CK down divided
modes are scaled directly from the CK CPU clock. If the external pin modes are used for
Timer/Counter2, transitions on PD7/(T2) will clock the counter even if the pin is config-
ured as an output. This feature can give the user software control of the counting.
Timer/Counter0 – TCNT0
Timer/Counter2 – TCNT2
These 8-bit registers contain the value of the Timer/Counters.
Table 11.
Timer/Counter0 Prescale Select
CS02
CS01
CS00
Description
0
0
0
Timer/Counter0 is stopped.
0
0
1
PCK0
0
1
0
PCK0/8
0
1
1
PCK0/32
1
0
0
PCK0/64
1
0
1
PCK0/128
1
1
0
PCK0/256
1
1
1
PCK0/1024
Table 12.
Timer/Counter2 Prescale Select
CS22
CS21
CS20
Description
0
0
0
Timer/Counter2 is stopped.
0
0
1
CK
0
1
0
CK/8
0
1
1
CK/64
1
0
0
CK/256
1
0
1
CK/1024
1
1
0
External Pin PD7(T2), falling edge
1
1
1
External Pin PD7(T2), rising edge
Bit
7
6
5
4
3
2
1
0
$32 ($42)
MSB
LSB
TCNT0
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
$24 ($44)
MSB
LSB
TCNT2
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