dsg333的专栏

https://blog.youkuaiyun.com/xuquanlin_1680/article/details/80502183

void USART2_Receive_Message(void) {   u16 remain;   u16 avail = RX_SIZE - RxLen_Buf2;   u16 count = RR_SIZE - DMA_GetCurrDataCounter(DMA1_Channel6);   if (count == RxPtr_Ring2 || avail == 0)