CAN被动错误恢复后，rt_device_write返回异常

发布于 2022-03-11 16:11:22 浏览：1400 订阅该版

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张世争 2022-03-11

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Memory_ 2022-03-11

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张世争 2022-03-11

学以致用

Code_Monkey 2022-03-11

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Assert 2022-04-01

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Assert 2022-04-01

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TXH97 2022-04-03

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mhxsoft 2022-04-30

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吕蛋蛋 2022-05-05

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自挂东南枝 2022-05-08

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- 一样的问题现象，出现时问题时，中断服务函数中判定应该是发送成功的
```c
       if (__HAL_CAN_GET_FLAG(hcan, CAN_FLAG_TXOK0))
        {
            rt_hw_can_isr(&drv_can1.device, RT_CAN_EVENT_TX_DONE | 0 << 8);
        }
```
这个判断可以进入，单步进入rt_hw_can_isr后发现进入到这里
```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;
```

`RT_CAN_EVENT_TX_DONE`这个case是没有break的，处理在下边`RT_CAN_EVENT_TX_FAIL`的case中处理，断点调试后发现返回的是成功
![image.png](https://oss-club.rt-thread.org/uploads/20220508/38b3d117ec1e54760e36909e04ad1529.png)  
最终回到_can_int_tx中时，结果如注释中写的，最终导致size返回0  
```c
 rt_completion_wait(&(tx_tosnd->completion), RT_WAITING_FOREVER);
 level = rt_hw_interrupt_disable();
 result = tx_tosnd->result;    //返回值是2
 if (!rt_list_isempty(&tx_tosnd->list))
 {
    rt_list_remove(&tx_tosnd->list);
 }
 rt_list_insert_before(&tx_fifo->freelist, &tx_tosnd->list);
 rt_hw_interrupt_enable(level);
 rt_sem_release(&(tx_fifo->sem));

if (result == RT_CAN_SND_RESULT_OK)//RT_CAN_SND_RESULT_OK： 0   RT_CAN_SND_RESULT_WAIT：2
 {
    level = rt_hw_interrupt_disable();
    can->status.sndpkg++;
    rt_hw_interrupt_enable(level);

data ++;
    msgs -= sizeof(struct rt_can_msg);
    if (!msgs) break;
 }
 else
 {
    level = rt_hw_interrupt_disable();
    can->status.dropedsndpkg++;
    rt_hw_interrupt_enable(level);
    break;
 }
```
第一次使用rt-thread，求解

用户名由3_15位 2022-10-11

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按照这个帖子的办法可以解决
https://club.rt-thread.org/ask/article/5cedb728813e6fd8.html

`drv_can.c`里，当CAN总线拔掉发送时，会进入ACK错误中断SCE，这时TSR的TXOK都是0，
另`CAN_FLAG_TXOK0/1/2`值的定义，还要移位才能对应，READ_BIT没有进行移位，所以下面这三个条件并不会执行，改为下面方式就可以执行了，并且清理了发送请求位`CAN_TSR_RQCP0/1/2`

```c
CAN1_SCE_IRQHandler(void)
{
    ......
    case RT_CAN_BUS_ACK_ERR:/* attention !!! test ack err's unit is transmit unit */
        drv_can1.device.status.ackerrcnt++;
        if (!READ_BIT(drv_can1.CanHandle.Instance->TSR, CAN_FLAG_TXOK0))
            rt_hw_can_isr(&drv_can1.device, RT_CAN_EVENT_TX_FAIL | 0 << 8);
        else if (!READ_BIT(drv_can1.CanHandle.Instance->TSR, CAN_FLAG_TXOK1))
            rt_hw_can_isr(&drv_can1.device, RT_CAN_EVENT_TX_FAIL | 1 << 8);
        else if (!READ_BIT(drv_can1.CanHandle.Instance->TSR, CAN_FLAG_TXOK2))
            rt_hw_can_isr(&drv_can1.device, RT_CAN_EVENT_TX_FAIL | 2 << 8);
        break;
    ......
}
```

———————-改为以下代码———————

```c
CAN1_SCE_IRQHandler(void)
{
    ......
    case RT_CAN_BUS_ACK_ERR:/* attention !!! test ack err's unit is transmit unit */
        drv_can1.device.status.ackerrcnt++;
        if (__HAL_CAN_GET_FLAG(hcan, CAN_FLAG_RQCP0))
        {
            if (!__HAL_CAN_GET_FLAG(hcan, CAN_FLAG_TXOK0))
            {
                rt_hw_can_isr(&drv_can1.device, RT_CAN_EVENT_TX_FAIL | 0 << 8);
            }
            SET_BIT(hcan->Instance->TSR, CAN_TSR_RQCP0);
        }
        else if (__HAL_CAN_GET_FLAG(hcan, CAN_FLAG_RQCP1))
        {
            if (!__HAL_CAN_GET_FLAG(hcan, CAN_FLAG_TXOK1))
            {
                rt_hw_can_isr(&drv_can1.device, RT_CAN_EVENT_TX_FAIL | 1 << 8);
            }
            SET_BIT(hcan->Instance->TSR, CAN_TSR_RQCP1);
        }
        else if (__HAL_CAN_GET_FLAG(hcan, CAN_FLAG_RQCP2))
        {
            if (!__HAL_CAN_GET_FLAG(hcan, CAN_FLAG_TXOK2))
            {
                rt_hw_can_isr(&drv_can1.device, RT_CAN_EVENT_TX_FAIL | 2 << 8);
            }
            SET_BIT(hcan->Instance->TSR, CAN_TSR_RQCP2);
        }
        break;
    ......
}
```