关键应该在这句
我翻译一下:
TASSEL1——ACLK
MC1——The timer repeatedly counts from zero to the value of TACCR0.
TACLR——Timer_A clear. Setting this bit resets TAR, the clock divider, and the count direction. The TACLR bit is automatically reset and is always read as zero.
ID0+ID1——=ID1,2分频