http://www.atmel.com/images/atmel-2486-8-bit-avr-microcontroller-atmega8_l_datasheet.pdf
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96쪽 (PWM관련)
ATmega128은 TCCR1A, TCCR1B, TCCR1C 의 3개의 채널을 갖고있는 반면
ATmega8은 TCCR1A, TCCR1B 의 2개의 채널을 갖고있다.
ATmega128에서의 TCCR1A Register Bit configuration ▼
TCCR1A = (1<<COM1A1)|(0<<COM1A0)|(0<<COM1B1)|(0<<COM1B0)|(0<<COM1C1)|(0<<COM1C0)|(1<<WGM11)|(0<<WGM10);
★COM1C1, COM1C0 비트가 있다.
반면...
ATmega8에서의 TCCR1A Register는 COM1C1, COM1C0 비트 없이 구성되어있다.
The FOC1A/FOC1B bits are only active
when the WGM13:0 bits specifies a non-PWM mode.
However, for ensuring compatibility with future devices,
these bits must be set to zero when TCCR1A is written when operating in a PWM mode.
When writing a logical one to the FOC1A/FOC1B bit,
an immediate Compare Match is forced on the waveform generation unit.
The OC1A/OC1B output is changed according to its COM1x1:0 bits setting.
Note that the FOC1A/FOC1B bits are implemented as strobes.
Therefore it is the value present in the COM1x1:0 bits that determine the effect of the forced compare.
