LP-AM243: MCAN Loopback Test (Interrupt) Extended Format Realization Method

Hi Yoshiki-San,

I am working on your queries, please expect a reply in 1-2 days.

Best Regards.

Meet.

Thanks.
Perform a loopback test using a 3-pin header (J11).

I test with CANFD before the classic CAN loopback test.
I intend to test classic CAN after CANFD is successful.

The sample code used mcan_loopback_interrupt.

App_mcanIntrISR() is executed, but MCAN_INTR_SRC_TRANS_COMPLETE is OFF.
Protocol Error in Data Phase interrupt occurs.
This error occurred during the CANFD loopback test. We believe it also occurs on classic CAN.
We do not use loopback mode.
What is wrong?

Hi Yoshiki-San,

I was able to reproduce this at my end, please allow me some more time to find the root cause.

Best Regards,

Meet.

Hello, Meet-San.
Did you find the cause of the problem?

Regards,
Yoshiki

Thanks. I will check!!

Hello, Meat-san.
I have checked mcan_transceiver.c.

file path:
  mcu_plus_sdk_am243x_10_01_00_32\examples\drivers\mcan\mcan_external_loopback_interrupt\am243x-evm\mcan_transceiver.c

I want to work sure with LP2434 board.
The mcan_transceiver.c controls the STB.
On LP2434, STB cannot be controlled.
EVM can control STB.

mcan_transceiver.c is not available in LP2434.
How can I do an external loopback with LP2434?

User's Guide "AM64x/AM243x Evaluation Module", p54-55
  STB pin of the IC is by default connected to ground to avoid IC entering stand-by mode.
  The STB pin is controlled by GPIO to enable Standby mode.

  In mcan_transceiver.c, the TCA6424 is controlled via I2C.

User's Guide "AM243x LaunchPad", p44
  The STB pin can be directly driven by the AM243x to enable standby mode.
  When not directly driven by the AM243x, the 10kΩ pulldown resistor puts the CAN interface IC into normal operation mode.

Regards,
Yoshiki

Hi Yoshiki-San,

Let me try this at my end once.

Hi Yoshiki-San,

There is a FAQ that guides on how to implement this external loopback and verify the functionality, please refer to the same: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1329465/faq-sk-am62x-sk-am62a-lp-testing-mcan-external-loopback-example-using-external-transceiver-tcan1042d

As you are using AM243-lp you don't need to use an external transceiver as it is already available on the board, but you will need to connect your transceiver's CANL and CANH to PCAN module and follow the steps mentioned in the FAQ.

Best Regards,

Meet.

Thanks. I will check!!!!!

Thanks.

Can communication is serial communication.
I thought I could just connect tx=>rx, rx=>tx like uart.
But this was a mistake.

https://software-dl.ti.com/processor-sdk-linux/esd/AM62AX/09_01_00/exports/docs/linux/How_to_Guides/Target/How_to_test_MCAN_on_AM62x.html#mcan-overview


CAN communication is not possible with a single board.
Two boards are required as shown in the figure.
I will have two LP-2434s.

AM64x /AM243x
Technical Reference Manual

I am transcribing the very first request.
“I would like to modify mcan_loopback_interrupt to check the loopback of the classic CAN extended format.”
"Q1.I would like the sample code, can I download it?”

I studied classic CAN in the online documentation.

  mcan_loopback_interrupt.c   This sample code is CANFD.
  mcan_loopback_polling.c     This sample code is Classic Can, CANID is 29bit.

1. I modify mcan_loopback_interrupt.c to ClassicCan.
2. I confirm loopback with CANID 11bit. 3. I modify mcan_loopback_interrupt.c to CANID 29bit.
3. I modify mcan_loopback_interrupt.c to CANID 29bit. mcan_loopback_polling.c confirmed.
4. I confirm loopback with CANID 29bit.
5. I confirm CANID 11bit communication with 2 LP boards.
6. I confirm CANID 29bit communication with 2 LP boards.

Result:.
2: Sending/receiving succeeds
4: Reception fails.

I do not know why CANID 29bit is failing.

I have corrected (*1)-(*5).

Classic CAN 11bit:
(*1)MCAN_InitParams::fdMode                   FALSE
    MCAN_InitParams::brsEnable                FALSE

(*2)MCAN_MsgRAMConfigParams::lss              APP_MCAN_STD_ID_FILTER_CNT(1)
    MCAN_MsgRAMConfigParams::lse              APP_MCAN_EXT_ID_FILTER_CNT(0)

(*3)MCAN_MsgRAMConfigParams::rxBufElemSize    MCAN_ELEM_SIZE_8BYTES(0)
    MCAN_MsgRAMConfigParams::rxFIFO0ElemSize  MCAN_ELEM_SIZE_8BYTES(0)
    MCAN_MsgRAMConfigParams::rxFIFO1ElemSize  MCAN_ELEM_SIZE_8BYTES(0)
    MCAN_MsgRAMConfigParams::txBufElemSize    MCAN_ELEM_SIZE_8BYTES(0)

(*4)MCAN_StdMsgIDFilterElement::sfid1         0xc0
    MCAN_StdMsgIDFilterElement::sfid2         0xc0
    MCAN_StdMsgIDFilterElement::sfec          MCAN_STD_FILT_ELEM_BUFFER(7)
    MCAN_StdMsgIDFilterElement::sft           MCAN_STD_FILT_TYPE_CLASSIC(2)

(*5)MCAN_TxBufElement::dlc                    MCAN_DATA_SIZE_8BYTES(0)
    MCAN_TxBufElement::fdf                    FALSE

Classic CAN 29bit:
(*1)MCAN_InitParams::fdMode                   FALSE
    MCAN_InitParams::brsEnable                FALSE

(*2)MCAN_MsgRAMConfigParams::lss              APP_MCAN_STD_ID_FILTER_CNT(0)
    MCAN_MsgRAMConfigParams::lse              APP_MCAN_EXT_ID_FILTER_CNT(1)

(*3)MCAN_MsgRAMConfigParams::rxBufElemSize    MCAN_ELEM_SIZE_8BYTES(0)
    MCAN_MsgRAMConfigParams::rxFIFO0ElemSize  MCAN_ELEM_SIZE_8BYTES(0)
    MCAN_MsgRAMConfigParams::rxFIFO1ElemSize  MCAN_ELEM_SIZE_8BYTES(0)
    MCAN_MsgRAMConfigParams::txBufElemSize    MCAN_ELEM_SIZE_8BYTES(0)

(*4)MCAN_ExtMsgIDFilterElement::efid1         0xd0
    MCAN_ExtMsgIDFilterElement::efid2         0xd0
    MCAN_ExtMsgIDFilterElement::efec          MCAN_EXT_FILT_ELEM_BUFFER(7)
    MCAN_StdMsgIDFilterElement::eft           MCAN_EXT_FILT_TYPE_CLASSIC(2)

(*5)MCAN_TxBufElement::id
    MCAN_TxBufElement::xtd                    FALSE
    MCAN_TxBufElement::dlc                    MCAN_DATA_SIZE_8BYTES
    MCAN_TxBufElement::fdf                    FALSE

What am I doing wrong?

Regards,
Yoshiki.

/// my init
{
    /* Initialize MCAN module initParams */
    MCAN_initOperModeParams(&initParams);
    initParams.fdMode          = FALSE;					// classic canはFALSE
    initParams.brsEnable       = FALSE;					// classic canはFALSE
}

/// my msgram config
static char trial_MCAN_MsgRAMConfigParams(uint32_t mode, MCAN_MsgRAMConfigParams *pConfig)
{
	MCAN_MsgRAMConfigParams	wk_cfg;

    if (pConfig == NULL)
    {
        return -1;
    }

    /*
	 * Configure the user required msg ram params
	 */

	// This API will initialize MCAN message config RAM params to default.
    MCAN_initMsgRamConfigParams(&wk_cfg);

	if (mode == MCAN_MODE_STANDARD)
	{
		wk_cfg.lss = LLD_MCAN_STD_ID_FILTER_CNT;		// List Size: Standard ID
	    wk_cfg.lse = 0;									// List Size: Extended ID
	}
	else
	{
		wk_cfg.lss = 0;									// List Size: Standard ID
	    wk_cfg.lse = LLD_MCAN_EXT_ID_FILTER_CNT;		// List Size: Extended ID
	}

	/* Maximum TX Buffer + TX FIFO, combined can be configured is 32 */
    wk_cfg.txBufCnt  = LLD_MCAN_TX_BUFF_CNT;			// (1)
    wk_cfg.txFIFOCnt = LLD_MCAN_TX_FIFO_CNT;			// (0)

    /* 
	 * Buffer/FIFO mode is selected
	 */
    wk_cfg.txBufMode = MCAN_TX_MEM_TYPE_BUF;

	/* Maximum TX Event FIFO can be configured is 32 */
    wk_cfg.txEventFIFOCnt = LLD_MCAN_TX_EVENT_FIFO_CNT;

	/* Maximum RX FIFO 0 can be configured is 64 */
    wk_cfg.rxFIFO0Cnt = LLD_MCAN_FIFO_0_CNT;

	/* Maximum RX FIFO 1 can be configured is 64 and
	 * rest of the memory is allocated to RX buffer which is again of max size 64 */
    wk_cfg.rxFIFO1Cnt = LLD_MCAN_FIFO_1_CNT;

    /* FIFO blocking mode is selected */
    wk_cfg.rxFIFO0OpMode = MCAN_RX_FIFO_OPERATION_MODE_BLOCKING;
    wk_cfg.rxFIFO1OpMode = MCAN_RX_FIFO_OPERATION_MODE_BLOCKING;

    wk_cfg.rxBufElemSize = MCAN_ELEM_SIZE_8BYTES;
    wk_cfg.rxFIFO0ElemSize = MCAN_ELEM_SIZE_8BYTES;
    wk_cfg.rxFIFO1ElemSize = MCAN_ELEM_SIZE_8BYTES;

	//This API will calculate start addresses of message RAM params
    (void)MCAN_calcMsgRamParamsStartAddr(&wk_cfg);

	(void)memcpy((void*)pConfig, &wk_cfg, sizeof(wk_cfg));
    return 0;
}

/// my std filter
static char trial_StdFilterElemParams(MCAN_StdMsgIDFilterElement *pstdFiltElem)
{
    if (pstdFiltElem == NULL)
    {
        return -1;
    }

    /* sfid1 defines the ID of the standard message to be stored. */
    pstdFiltElem->sfid1 = 0;
    /* As buffer mode is selected, sfid2 should be bufNum[0 - 63] */
    pstdFiltElem->sfid2 = 0;

    /* Store message in buffer */
	// Store into Rx Buffer or as debug message, configuration of SFT[1:0] ignored.
    pstdFiltElem->sfec  = MCAN_STD_FILT_ELEM_BUFFER;

#if 0
uint32_t sft;		
/**< Standard Filter Type		
 *   00 = Range filter from SFID1 to SFID2 (SFID2 ≥ SFID1)		
 *   01 = Dual ID filter for SFID1 or SFID2		
 *   10 = Classic filter: SFID1 = filter, SFID2 = mask		
 *   11 = Filter element disabled		
 */
#endif

    /* Below configuration is ignored if message is stored in buffer */
    pstdFiltElem->sft   = MCAN_STD_FILT_TYPE_CLASSIC;

    return 0;
}

/// my std filter
{
	(void)trial_StdFilterElemParams(&stdFiltElem[0]);
	stdFiltElem[0].sfid1 = pTrial->acceptanceCode;	// 0x0c
	stdFiltElem[0].sfid2 = pTrial->acceptanceMask;	// 0x0c
}

/// my ext filter
static char trial_ExtFilterElemParams(MCAN_ExtMsgIDFilterElement *pextFiltElem)
{
    if (pextFiltElem == NULL)
    {
        return -1;
    }

    /* efid1 defines the ID of the standard message to be stored.
     * Message id configured is 0xD0 to 0xD4 */
    pextFiltElem->efid1 = 0;
    /* As fifo mode is selected, efid2 should be mask */
    pextFiltElem->efid2 = 0;

    /* Store message in buffer */
    //pextFiltElem->efec  = MCAN_STD_FILT_ELEM_FIFO0;
    pextFiltElem->efec  = MCAN_EXT_FILT_ELEM_BUFFER;
 
#if 0
uint32_t eft;								
/**< Extended Filter Type								
 *   00 = Range filter from EFID1 to EFID2 (EFID2 ≥ EFID1)								
 *   01 = Dual ID filter for EFID1 or EFID2								
 *   10 = Classic filter: EFID1 = filter, EFID2 = mask								
 *   11 = Range filter from EFID1 to EFID2 (EFID2 ≥ EFID1),								
 *        XIDAM mask not applied								
 */								
#endif
   /* Below configuration is ignored if message is stored in buffer */
    pextFiltElem->eft   = MCAN_STD_FILT_TYPE_CLASSIC;

    return 0;
}

/// my ext filter
{
	(void)trial_ExtFilterElemParams(&extFiltElem[0]);
	extFiltElem[0].efid1 = pTrial->acceptanceCode;	// 0xd0
	extFiltElem[0].efid2 = pTrial->acceptanceMask;	// 0xd0
}

/// my send config
char trial_SendConfig(
			uint32_t				baseAddr,
			uint32_t				mode,
			TRIAL_t*				pTrial,
			MCAN_TxBufElement*		plld_tx )
{
	MCAN_TxBufElement	wk_tx;
	uint8_t             ii;

	/* Initialize message to transmit */
    MCAN_initTxBufElement(&wk_tx);

	/**< Identifier */
	wk_tx.id = (uint32_t)pTrial->id;

	/**< Remote Transmission Reques
	     *   0 = Transmit data frame
	     *   1 = Transmit remote frame
	*/
	wk_tx.rtr = pTrial->frame;

	/**< Extended Identifier
	     *   0 = 11-bit standard identifier
	     *   1 = 29-bit extended identifier
	*/
	wk_tx.xtd = TRUE;
	//if( m_UsrParam[channel].mode == MCAN_MODE_STANDARD )
	if( mode == MCAN_MODE_STANDARD )
	{
		wk_tx.xtd = FALSE;
	}

	/**< FD Format	
	     *   0 = Frame transmitted in Classic CAN format	
	     *   1 = Frame transmitted in CAN FD format	
	*/
	wk_tx.fdf = FALSE;

	/**< Data Length Code
	     *   0-8  = CAN + CAN FD: transmit frame has 0-8 data bytes
	     *   9-15 = CAN: transmit frame has 8 data bytes
	     *   9-15 = CAN FD: transmit frame has 12/16/20/24/32/48/64 data bytes
	*/
	wk_tx.dlc = pTrial->length;

	for(ii = 0; ii < pTrial->length; ii++)
	{
		wk_tx.data[ii] = pTrial->data[ii];
	}

	memcpy((void*)plld_tx, &wk_tx, sizeof(wk_tx));

	return 0;
}

The value of the interrupt status (INT status) is 0x0000 8200.

What is wrong with my parameters?

Hi Yoshki-San,

Please allow me some more time to review the code and get back to you.

Best Regards,

Meet.

mcan_loopback_interrupt.c sets the following structures
  MCAN_InitParams
  MCAN_ConfigParams
  MCAN_MsgRAMConfigParams
  MCAN_StdMsgIDFilterElement
  MCAN_ExtMsgIDFilterElement
  MCAN_BitTimingParams
  MCAN_TxBufElement

I believe that by modifying these structures, I can send and receive CANID 11bit and 29bit. Am I right?

Regards,
Yoshiki.

Hi Thaker,

There are a lot of discussion here.

1st of all, could you focus 29bit mode for internal loop back, test it  and share the code with Yoshiki-san?

Thank you.

Best Regards,

Kasai

Hi Kasai-San, Yoshiki-San,

mcan_loopback_polling is using 29-bit ID, I understand Yoshiki-San is trying to enable the same for the interrupt example and facing some issue. Please note that interrupt example uses buffer mode and if you are using the buffer mode efid2 has to be set to the buffer number, I see that it is set to 0xD0 here, I am not sure of the reason, but ideally it should be set to buffer number. I will try to run the example at my end and let you know what other changes might be required here.

Best Regards,

Meet.