topic Re: Receive MCAN message by calling function MCAN_DRV_RxFifo in S32 SDK

Receive MCAN message by calling function MCAN_DRV_RxFifo

Tangsheng_Zhou — Thu, 19 Sep 2019 03:20:14 GMT

After init the MCAN module and install callback, start receiving MCAN message by calling MCAN_DRV_RxFifo in callback function.

The init code :

MCAN_DRV_Init(CAN_CH1, &McanCom1_State, &McanCom1_mcan_user_config_t0);

MCAN_DRV_InstallEventCallback(CAN_CH1, (mcan_callback_t)Mcan1InterruptCallback, NULL);
MCAN_DRV_ConfigRxFifo(CAN_CH1, (mcan_id_table_t **)&McanCom1_mcan_id_table_t0[0], 1);
MCAN_DRV_RxFifo(CAN_CH1, 0, recvMsgBuff);

The fuction callback code:

static void Mcan1InterruptCallback(uint8_t instance,
mcan_event_type_t eventType,
uint32_t idx,
mcan_state_t *mcanState)
{
      DEV_ASSERT(mcanState != NULL);
      mcan_msgbuff_t *recvBuff = &s_mcanMsgBuff;
      M_CAN_Type * base = g_mcanBase[instance];
      uint8_t value = 0U;

      switch (eventType)
      {
      case MCAN_EVENT_TX_COMPLETE:
            break;
      case MCAN_EVENT_RX0FIFO_COMPLETE:
            MCAN_DRV_RxFifo(instance, 0, recvBuff);
            break;
      case MCAN_EVENT_RX0FIFO_WARNING:
            MCAN_DRV_RxFifo(instance, 0, recvBuff);
            break;
       case MCAN_EVENT_RX0FIFO_OVERFLOW:
            break;
      default:
            printf("other type = %d \r\n", eventType);
            break;
      }
}

When received CAN message, generated interrupt and called callback fucnftion Mcan1InterruptCallback, and eventType = MCAN_EVENT_RX0FIFO_COMPLETE, then called function MCAN_DRV_RxFifo(instance, 0, recvBuff). Line 1685-1707 in mcan_driver.c, if the number of received message is greater than 1, the callback function will call itself in mcan_driver.c line 1074 function static void MCAN_CompleteRxFIFO(uint8_t instance,mode_type_t type). If the number of CAN message is greater than 1 all the time, the callback fucntion will always call itself and will cause stack overflow.

Maybe I do not write the callback fucntion, If it is wrong, how do I write the callback function.

Re: Receive MCAN message by calling function MCAN_DRV_RxFifo

alexandrunan — Thu, 19 Sep 2019 09:00:07 GMT

Hello,

What water mark level did you configured for generation of MCAN_EVENT_RX0FIFO_WARNING.

The overflow can be caused because if you call another receive from a callback function, this is not allowed because will not allow you to end current ISR. The callbacks are made only for notifications not for driver state changes.

volatile bool finished_transfer = false;
static void Mcan1InterruptCallback(uint8_t instance,
mcan_event_type_t eventType,
uint32_t idx,
mcan_state_t *mcanState)
{
DEV_ASSERT(mcanState != NULL);
mcan_msgbuff_t *recvBuff = &s_mcanMsgBuff;
M_CAN_Type * base = g_mcanBase[instance];
uint8_t value = 0U;

switch (eventType)
{
case MCAN_EVENT_TX_COMPLETE:
break;
case MCAN_EVENT_RX0FIFO_COMPLETE:
/* fall-true */
case MCAN_EVENT_RX0FIFO_WARNING:
finished_transfer = true;
break;
case MCAN_EVENT_RX0FIFO_OVERFLOW:
break;
default:
printf("other type = %d \r\n", eventType);
break;
}
}

somehere in your main loop

if (finished_transfer == true)
{
MCAN_DRV_RxFifo(instance, 0, recvBuff);
finished_transfer = false;
}

BR,

Alexandru Nan

Re: Receive MCAN message by calling function MCAN_DRV_RxFifo

Tangsheng_Zhou — Thu, 19 Sep 2019 09:31:24 GMT

Thank you for your help.

When the fifo element number is 64 or other value, what watermark level should be. Is there some tpy value or set the value whatever I want.