STM32cubemx-HAL库串口断线问题

STM32cubemx：version5.1

Chip: STM32F446RE

IDE:Keil5

Q：小项目上写了个简单的通信包，波特率230400，数据量较大1600Byte/s,DMA的方式实现接收，量产后发现跑久了部分机器会有只能发送不能接收的问题。

查了很久没查到。中间加了断线检测，重新初始化串口，却无法解决。最后面发现，HAL的锅。

部分代码：

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
if(huart->Instance == UART4) {
uint8_t ret=HAL_OK;
if(frame_in_sync) {
if(UART_Rx_Buffer.head == 0x55 && UART_Rx_Buffer.end == 0xAA) { // TODO: check check-sum
UART_Rx_Data = UART_Rx_Buffer;
ret=HAL_UART_Receive_IT(&huart4, (uint8_t *)&UART_Rx_Buffer, sizeof(UART_Rx_Buffer));
uart_updata_time= HAL_GetTick();

} else { // frame not in sync, drop coming bytes until read an end(0xAA)
frame_in_sync = 0;
ret=HAL_UART_Receive_IT(&huart4, (uint8_t *)&UART_Rx_Buffer, 1);
}
} else {
　if( *(uint8_t *)&UART_Rx_Buffer == 0xAA) {
frame_in_sync = 1;
ret=HAL_UART_Receive_IT(&huart4, (uint8_t *)&UART_Rx_Buffer, sizeof(UART_Rx_Buffer));
} else {
ret=HAL_UART_Receive_IT(&huart4, (uint8_t *)&UART_Rx_Buffer, 1);
}
}
}
}

上述的代码绝大多数时间都能够正常运行。但是，总会出现莫名奇妙的掉线问题。并且难以复线。查了好久，看到有类似的问题，HAL库会不处理异常的行为，要用户处理。

在某些情况下，HAL_UART_Receive_IT 并没有成功执行，返回了busy 或者erro，这时候整个流程就背打断了。并且串口还会被莫名其妙锁上。

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
if(huart->Instance == UART4) {
uint8_t ret=HAL_OK;
if(frame_in_sync) {
if(UART_Rx_Buffer.head == 0x55 && UART_Rx_Buffer.end == 0xAA) { // TODO: check check-sum
UART_Rx_Data = UART_Rx_Buffer;
ret=HAL_UART_Receive_IT(&huart4, (uint8_t *)&UART_Rx_Buffer, sizeof(UART_Rx_Buffer));
uart_updata_time= HAL_GetTick();

} else { // frame not in sync, drop coming bytes until read an end(0xAA)
frame_in_sync = 0;
ret=HAL_UART_Receive_IT(&huart4, (uint8_t *)&UART_Rx_Buffer, 1);
}
} else {
if( *(uint8_t *)&UART_Rx_Buffer == 0xAA) {
frame_in_sync = 1;
ret=HAL_UART_Receive_IT(&huart4, (uint8_t *)&UART_Rx_Buffer, sizeof(UART_Rx_Buffer));
} else {
ret=HAL_UART_Receive_IT(&huart4, (uint8_t *)&UART_Rx_Buffer, 1);
}
}
while(ret!=HAL_OK){
/*try to fix connection bug  20191225*/
printf("UART4:RECEIVE_IT:%d\r\n",ret);　　//for log
huart->RxState = HAL_UART_STATE_READY;
__HAL_UNLOCK(huart);
ret=HAL_UART_Receive_IT(&huart4, (uint8_t *)&UART_Rx_Buffer, 1);
}
}
}

void HAL_UART_ErrorCallback(UART_HandleTypeDef *huart)
{
/* Prevent unused argument(s) compilation warning */
if(huart->ErrorCode&HAL_UART_ERROR_ORE)
{
__HAL_UART_CLEAR_OREFLAG(huart);
}
/* NOTE : This function should not be modified, when the callback is needed,
the HAL_UART_ErrorCallback can be implemented in the user file.
*/
}

修改后，出现busy或者erro时强制解锁，重新接收。根据log，大约半小时会出现一次。三台经常性出现的机子更新后运行一天，没有出现这个问题。在log中查看到了对应的修正过程。