Tcnt2 - timer/counter register, Ocr2a - output compare register a – Rainbow Electronics ATmega3290P_V User Manual
Page 146
146
ATmega329/3290/649/6490
2552H–AVR–11/06
The three Clock Select bits select the clock source to be used by the Timer/Counter, see
Table 71.
TCNT2 – Timer/Counter
Register
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.
OCR2A – Output Compare
Register A
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.
Table 71. Clock Select Bit Description
CS22
CS21
CS20
Description
0
0
0
No clock source (Timer/Counter stopped).
0
0
1
clk
T2S
/(No prescaling)
0
1
0
clk
T2S
/8 (From prescaler)
0
1
1
clk
T2S
/32 (From prescaler)
1
0
0
clk
T2S
/64 (From prescaler)
1
0
1
clk
T2S
/128 (From prescaler)
1
1
0
clk
T
2
S
/256 (From prescaler)
1
1
1
clk
T
2
S
/1024 (From prescaler)
Bit
7
6
5
4
3
2
1
0
TCNT2[7:0]
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
Bit
7
6
5
4
3
2
1
0
OCR2A[7:0]
OCR2A
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