Datasheet
19.9.2 TC0 Control Register B
Name: TCCR0B
Offset: 0x45
Reset: 0x00
Property: When addressing as I/O register: address offset is 0x25
Bit 7 6 5 4 3 2 1 0
FOC0A FOC0B WGM02 CS0[2:0]
Access
R/W R/W R/W R/W R/W R/W
Reset 0 0 0 0 0 0
Bit 7 – FOC0A Force Output Compare A
The FOC0A 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 TCCR0B is written when
operating in PWM mode. When writing a logical one to the FOC0A bit, an immediate compare match is
forced on the waveform generation unit. The OC0A output is changed according to its COM0A[1:0] bits
setting. The FOC0A bit is implemented as a strobe. Therefore, it is the value present in the COM0A[1:0]
bits that determines the effect of the forced compare.
A FOC0A strobe will not generate any interrupt, nor will it clear the timer in CTC mode using OCR0A as
TOP.
The FOC0A bit is always read as zero.
Bit 6 – FOC0B Force Output Compare B
The FOC0B 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 TCCR0B is written when
operating in PWM mode. When writing a logical one to the FOC0B bit, an immediate compare match is
forced on the waveform generation unit. The OC0B output is changed according to its COM0B[1:0] bits
setting. The FOC0B bit is implemented as a strobe. Therefore, it is the value present in the COM0B[1:0]
bits that determines the effect of the forced compare.
A FOC0B strobe will not generate any interrupt, nor will it clear the timer in CTC mode using OCR0B as
TOP.
The FOC0B bit is always read as zero.
Bit 3 – WGM02 Waveform Generation Mode
Refer to TCCR0A register.
Bits 2:0 – CS0[2:0] Clock Select 0
The three clock select bits select the clock source to be used by the timer/counter.
Table 19-10. Clock Select Bit Description
CS0[2] CS0[1] CS0[0] Description
0 0 0 No clock source (timer/counter stopped)
0 0 1 clk
I/O
/1 (no prescaling)
ATmega48PA/88PA/168PA
8-bit Timer/Counter0 (TC0) with PWM
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40002011A-page 153