RT-Thread-STM32H743的FDCAN如果上电时总线上并没有其他CAN设备会导致CAN发送线程卡死的处理方法RT-Thread问答社区

STM32H743的FDCAN如果上电时总线上并没有其他CAN设备会导致CAN发送线程卡死的处理方法

发布于 2023-02-24 15:45:08 浏览：1519 订阅该版

芯片型号STM32H743IIT6，测试时发现如果外面没有连接CAN设备，程序调用CAN发送时会一直等待发送反馈，导致相关线程挂起。
分析发现是卡在can.c文件的168行_can_int_tx函数：`rt_completion_wait(&(tx_tosnd->completion), RT_WAITING_FOREVER);`

```c
rt_inline int _can_int_tx(struct rt_can_device *can, const struct rt_can_msg *data, int msgs)
{
    int size;
    struct rt_can_tx_fifo *tx_fifo;

RT_ASSERT(can != RT_NULL);

size = msgs;
    tx_fifo = (struct rt_can_tx_fifo *) can->can_tx;
    RT_ASSERT(tx_fifo != RT_NULL);

while (msgs)
    {
        rt_base_t level;
        rt_uint32_t no;
        rt_uint32_t result;
        struct rt_can_sndbxinx_list *tx_tosnd = RT_NULL;

rt_sem_take(&(tx_fifo->sem), RT_WAITING_FOREVER);
        level = rt_hw_interrupt_disable();
        tx_tosnd = rt_list_entry(tx_fifo->freelist.next, struct rt_can_sndbxinx_list, list);
        RT_ASSERT(tx_tosnd != RT_NULL);
        rt_list_remove(&tx_tosnd->list);
        rt_hw_interrupt_enable(level);

no = ((rt_uint32_t)tx_tosnd - (rt_uint32_t)tx_fifo->buffer) / sizeof(struct rt_can_sndbxinx_list);
        tx_tosnd->result = RT_CAN_SND_RESULT_WAIT;
        if (can->ops->sendmsg(can, data, no) != RT_EOK)
        {
            /* send failed. */
            level = rt_hw_interrupt_disable();
            rt_list_insert_after(&tx_fifo->freelist, &tx_tosnd->list);
            rt_hw_interrupt_enable(level);
            rt_sem_release(&(tx_fifo->sem));
            continue;
        }

can->status.sndchange = 1;
        rt_completion_wait(&(tx_tosnd->completion), RT_WAITING_FOREVER);
```
说明一直在等待完成信号，而发送完成信号的地方在can.c文件的900行rt_hw_can_isr函数：`rt_completion_done(&(tx_fifo->buffer[no].completion));`

```c
    case RT_CAN_EVENT_TX_DONE:
    case RT_CAN_EVENT_TX_FAIL:
    {
        struct rt_can_tx_fifo *tx_fifo;
        rt_uint32_t no;
        no = event >> 8;
        tx_fifo = (struct rt_can_tx_fifo *) can->can_tx;
        RT_ASSERT(tx_fifo != RT_NULL);

if ((event & 0xff) == RT_CAN_EVENT_TX_DONE)
        {
            tx_fifo->buffer[no].result = RT_CAN_SND_RESULT_OK;
        }
        else
        {
            tx_fifo->buffer[no].result = RT_CAN_SND_RESULT_ERR;
        }
        rt_completion_done(&(tx_fifo->buffer[no].completion));
        break;
    }
```
然后想到如果can总线没有其他设备，CAN发送报文应该属于出错的情况，查看`drv_fdcan.c`文件中关于几种中断的处理，发现故障后的回调函数里没有调用`rt_hw_can_isr`。
于是参考`HAL_FDCAN_TxBufferCompleteCallback`函数的处理方式，对`HAL_FDCAN_ErrorCallback`进行了如下处理。

```c
void HAL_FDCAN_ErrorCallback(FDCAN_HandleTypeDef *hfdcan)
{
	rt_uint32_t tmp_u32Errcount;
	rt_uint32_t tmp_u32status;
	uint32_t ret = HAL_FDCAN_GetError(hfdcan);

if(hfdcan->Instance == FDCAN1)
	{
#ifdef BSP_USING_FDCAN1
		//can1
		if(	(ret & FDCAN_IT_ARB_PROTOCOL_ERROR) &&
			(hfdcan->Instance->CCCR & FDCAN_CCCR_INIT_Msk))
		{
			//hfdcan->Instance->CCCR |= FDCAN_CCCR_CCE_Msk;
			hfdcan->Instance->CCCR &= ~FDCAN_CCCR_INIT_Msk;
			st_DrvCan1.device.status.errcode = 0xff;
		}
		else
		{
			tmp_u32Errcount = st_DrvCan1.fdcanHandle.Instance->ECR;
			tmp_u32status = st_DrvCan1.fdcanHandle.Instance->PSR;

st_DrvCan1.device.status.rcverrcnt = (tmp_u32Errcount>>8)&0x000000ff;
			st_DrvCan1.device.status.snderrcnt = (tmp_u32Errcount)&0x000000ff;
			st_DrvCan1.device.status.lasterrtype = tmp_u32status&0x000000007;

rt_hw_can_isr(&st_DrvCan1.device, RT_CAN_EVENT_TX_FAIL);
		}
#endif /*BSP_USING_FDCAN1*/
	}
	else
	{
#ifdef BSP_USING_FDCAN2
		if(	(ret & FDCAN_IT_ARB_PROTOCOL_ERROR) &&
			(hfdcan->Instance->CCCR & FDCAN_CCCR_INIT_Msk))
		{
			//hfdcan->Instance->CCCR |= FDCAN_CCCR_CCE_Msk;
			hfdcan->Instance->CCCR &= ~FDCAN_CCCR_INIT_Msk;
			st_DrvCan2.device.status.errcode = 0xff;
		}
		else
		{
			//can2
			tmp_u32Errcount = st_DrvCan2.fdcanHandle.Instance->ECR;
			tmp_u32status = st_DrvCan2.fdcanHandle.Instance->PSR;
			st_DrvCan2.device.status.rcverrcnt = (tmp_u32Errcount>>8)&0x000000ff;
			st_DrvCan2.device.status.snderrcnt = (tmp_u32Errcount)&0x000000ff;
			st_DrvCan2.device.status.lasterrtype = tmp_u32status&0x000000007;

rt_hw_can_isr(&st_DrvCan2.device, RT_CAN_EVENT_TX_FAIL);
		}
#endif /*BSP_USING_FDCAN2*/
	}
}
```

经过测试发现即使CAN总线上没有别的设备，调用发送函数也不会一直等待，而是返回发送失败。