Bit7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
FOC2A | FOC2B | WGM2 [2] | CS2[2:0] | ||||
AccessR/W | R/W | R/W | R/W | R/W | R/W | ||
Reset0 | 0 | 0 | 0 | 0 | 0 |
Force Output Compare A
The FOC2A bit is only active when the WGM bits specify a non-PWM mode.
To ensure compatibility with future devices, this bit must be set to zero when TCCR2B is written when operating in PWM mode. When writing a logical one to the FOC2A bit, an immediate Compare Match is forced on the Waveform Generation unit. The OC2A output is changed according to its COM2A[1:0] bits setting. Note that the FOC2A bit is implemented as a strobe. Therefore it is the value present in the COM2A[1:0] bits that determines the effect of the forced compare.
A FOC2A strobe will not generate any interrupt, nor will it clear the timer in CTC mode using OCR2A as TOP.
The FOC2A bit is always read as zero.
Force Output Compare B
The FOC2B bit is only active when the WGM bits specify a non-PWM mode.
To ensure compatibility with future devices, this bit must be set to zero when TCCR2B is written when operating in PWM mode. When writing a logical one to the FOC2B bit, an immediate Compare Match is forced on the Waveform Generation unit. The OC2B output is changed according to its COM2B[1:0] bits setting. Note that the FOC2B bit is implemented as a strobe. Therefore it is the value present in the COM2B[1:0] bits that determines the effect of the forced compare.
A FOC2B strobe will not generate any interrupt, nor will it clear the timer in CTC mode using OCR2B as TOP.
The FOC2B bit is always read as zero.
Waveform Generation Mode
Clock Select 2 [n = 0..2]
The three Clock Select bits select the clock source to be used by the Timer/Counter.
CA22 | CA21 | CS20 | Description |
---|---|---|---|
0 | 0 | 0 | No clock source (Timer/Counter stopped). |
0 | 1 | clkI/O/1 (No prescaling) | |
0 | 1 | 0 | clkI/O/8 (From prescaler) |
0 | 1 | 1 | clkI/O/32 (From prescaler) |
1 | 0 | 0 | clkI/O/64 (From prescaler) |
1 | 0 | 1 | clkI/O/128 (From prescaler) |
1 | 1 | 0 | clkI/O/256 (From prescaler) |
1 | 1 | 1 | clkI/O/1024 (From prescaler) |
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.