Datasheet

ATmega48/88/168 Automotive [DATASHEET]
7530K–AVR–07/14
132
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.
15.8.3 Timer/Counter Register – TCNT2
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 OCR2x
registers.
15.8.4 Output Compare Register A – OCR2A
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.
15.8.5 Output Compare Register B – OCR2B
The output compare register B 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 OC2B pin.
Table 15-9. 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 76543210
TCNT2[7:0] TCNT2
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
Bit 76543210
OCR2A[7:0] OCR2A
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
Bit 76543210
OCR2B[7:0] OCR2B
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000