ATMEGA325-16AJ ATMEL [ATMEL Corporation], ATMEGA325-16AJ Datasheet - Page 137

• Manufacturer Part Number: ATMEGA325-16AJ
• Description: 8-bit Microcontroller with In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Timer/Counter Register –
TCNT2
Output Compare Register A -
OCR2A
2570A–AVR–09/04
The three Clock Select bits select the clock source to be used by the Timer/Counter, see
Table 63.
Table 63. 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 TCNT2 Register blocks (removes)
the compare match on the following timer clock. Modifying the counter (TCNT2) while
the counter is running, introduces a risk of missing a compare match between TCNT2
and the OCR2A Register.
The Output Compare Register A contains an 8-bit value that is continuously compared
with the counter value (TCNT2). A match can be used to generate an Output Compare
interrupt, or to generate a waveform output on the OC2A pin.
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
CS22
0
0
0
0
1
1
1
1
R/W
R/W
7
0
7
0
CS21
0
0
1
1
0
0
1
1
R/W
R/W
6
0
6
0
CS20
R/W
R/W
0
1
0
1
0
1
0
1
5
0
5
0
ATmega325/3250/645/6450
R/W
R/W
Description
No clock source (Timer/Counter stopped).
clk
clk
clk
clk
clk
clk
clk
4
0
4
0
OCR2A[7:0]
TCNT2[7:0]
T2S
T2S
T2S
T2S
T2S
T
T
2
2
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
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
OCR2A
TCNT2
137