TX CAN interrupt is missing?

Youngmin Kim

Other Parts Discussed in Thread: TM4C1290NCZAD

Hello,

I am working on Tiva TM4C1290NCZAD Microcontroller.
I send CAN messages with 8bytes data in every 1ms and receive some other in every 50ms in one device.
My problem is that the TX CAN interrupt is missing occasionally.
(The TX CAN interrupt is generated after the completion of transmission.)
When I send TX messages only, there is no problem (no missing TX interrupt).
And when I send it every 5 ms with RX, there is no problem as well.
The problem happens only if CAN bus is highly used in both ways.

Does TM4C controller guarantee CAN TX interrupt even though the CAN Bus is very busy?

Can you help me?

Regards,
Young

over 9 years ago

0 Youngmin Kim over 9 years ago

Prodigy 190 points

PS. To send a CAN Message, I used CANMessageSet() function.

0 Amit Ashara over 9 years ago

TI__Guru**** 244410 points

Hello Youngmin,

The TX interrupt is generated on a successful transmission. So if the Bus is busy, then it cannot be guaranteed, that it will be generated whenever TX is requested.

Regards
Amit

0 Youngmin Kim over 9 years ago in reply to Amit Ashara

Prodigy 190 points

Hi Amit,

Thank you for the clear answer.
I have one more question. Is there any way to check if the transmission fails after CANMessageSet()?

Cheers,
Young

0 Amit Ashara over 9 years ago in reply to Youngmin Kim

TI__Guru**** 244410 points

Hello Youngmin

Yes. if the CANINT register reads a value 0x8000, then the CANSTS register must be read to see what was the LEC value

Regards
Amit

0 Youngmin Kim over 9 years ago in reply to Amit Ashara

Prodigy 190 points

Hi Amit,

When I didn't receive TX interrupt, I couldn't see any LEC value.

This is my interrupt handler:

    Void CANIntHandler(UArg arg)
    {
        uint32_t status = 0;

        status = CANIntStatus(CAN_BASE, CAN_INT_STS_CAUSE);

        if( status == CAN_INT_INTID_STATUS)
        {
            status = CANStatusGet(CAN_BASE, CAN_STS_CONTROL);
            if(status & CAN_STATUS_BUS_OFF)
            {
            }
            if(status & CAN_STATUS_EWARN)
            {
            }
            if(status & CAN_STATUS_EPASS)
            {
            }
            if(status & CAN_STATUS_RXOK)
            {
            }
            if(status & CAN_STATUS_TXOK)
            {
            }
            if(status & CAN_STATUS_LEC_MSK) 
            {
                //printfLog(5, "Can LEC error, status=0x%x \r\n", status);
                Event_post(canInterruptEvent, Event_Id_29);
            }
        }
        else 
        {
            CANIntClear(CAN_BASE, status);

            if (status < TX_CAN_OBJ_ID)
            {
                // for RX packets
                canMessageObject = status;
                Event_post(canInterruptEvent, Event_Id_31);
            }
            else if (status > TX_CAN_OBJ_ID)
            {    // for TX packets
                Event_post(canInterruptEvent, Event_Id_30);
            }
        }
    }

Regards,
Young

0 Amit Ashara over 9 years ago in reply to Youngmin Kim

TI__Guru**** 244410 points

Hello Young,

The probable cause of why this may be occurring is the CAN controller sees the Bus Busy.

Regards
Amit

0 Youngmin Kim over 9 years ago in reply to Amit Ashara

Prodigy 190 points

Hi Amit,

If so, the CAN controller sees the Bus Busy, is there any reaction from the controller?
Does it discard the message?
I hope it should do something!

Regards,
Young

0 Amit Ashara over 9 years ago in reply to Youngmin Kim

TI__Guru**** 244410 points

Hello Youngmin,

It should hold back for a frame to complete.

Regards
Amit

0 Youngmin Kim over 9 years ago in reply to Amit Ashara

Prodigy 190 points

Hi Amit,

Oh I see.
How can I check if the Bus is busy?

Regards,
Young

0 Amit Ashara over 9 years ago in reply to Youngmin Kim

TI__Guru**** 244410 points

Hello Young,

I believe, it is the controller's responsibility. When a CAN transmission is requested, the BUSY bit is set CANIFnCRQ register which is cleared after the message is transmitted on the bus.

Regards
Amit

0 Youngmin Kim over 9 years ago in reply to Amit Ashara

Prodigy 190 points

Hi Amit,

I think I found a solution.
When I use BUSY bit of CANIFnCRQ register, there are missing messages sometimes.
But when I use TXRQST bit of CANTXRQn, everything is going alright.

Thank you so much for your help.

Regards,
Young

0 Amit Ashara over 9 years ago in reply to Youngmin Kim

TI__Guru**** 244410 points

Hello Youngmin,

You are welcome and thank you for contributing to the forum as well

Regards
Amit

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TX CAN interrupt is missing?