ʾʹõԴ
TIM1 CH1     --   PA15
TIM1 CH2     --   PB3
TIM1 CH3     --   PB4
TIM1 CH4     --   PB5

ʾḶ́
1ϵʱӣRCH 72MHz
2TIM1ͨ1~4ֱΪPWM
3TIM1ĸ¼DMA䣻
4ѭִ²ʵָıռձȹܣ
   a磬¼ʱDMA Burst䣻
   bDMAʱg_src_bufferеݷֱ䵽CC1~CC4ĴС