Example_MPC5748G_FlexCAN_FD_TX_RX_test_S32DS_21 usage question?

[xiha]

My project referred to the routine of the website.(Example_MPC5748G_FlexCAN_FD_TX_RX_test_S32DS_21 )

When I use this exmple provided by the website to send data, flexcan has access to the data I send???why I can get the data that I send.

/* enable the FlexCAN module, reset and freeze */
CAN_0.MCR.R = (0
| FLEXCAN_MCR_FRZ /* enabled to enter Freeze mode */
| FLEXCAN_MCR_HALT /* enter freeze mode if FRZ bit is set */
//| FLEXCAN_MCR_SOFTRST /* soft reset */
//| FLEXCAN_MCR_SRXDIS /* self reception enabled */
| FLEXCAN_MCR_BCC /* individual Rx masking and queue */
| 0x00000003);

/*******************************************************************************

Function Name : TransmitMsgFD

Engineer      : Petr Stancik

Date          : Jun-22-2021

Parameters    : mb ... mb number used

                ext ... 0-standard ID, 1-extended ID

                ID ... ID to be sent

                length ... number of bytes to be sent

Modifies      : NONE

Returns       : NONE

Notes         : Transmit message once using selected MB

Issues        : NONE

*******************************************************************************/

void TransmitMsgFD(uint32_t mb, uint8_t ext, uint32_t ID, uint8_t length)

{

/* Assumption:  Message buffer CODE is INACTIVE */

  uint8_t   i,dlc,z=0;

  uint32_t *pTxMB = GetMBAddr(mb);

  uint32_t txID = (ext==0) ? ID<<18 : ID;

  /*calculate dlc value from no. bytes*/

  if(length < 0x09)

  {

      dlc = length;

  }else if(length < 0x0D){

      dlc = 0x9;

  }else if(length < 0x11){

      dlc = 0xA;

  }else if(length < 0x15){

      dlc = 0xB;

  }else if(length < 0x19){

      dlc = 0xC;

  }else if(length < 0x21){

      dlc = 0xD;

  }else if(length < 0x31){

      dlc = 0xE;

  }else{

      dlc = 0xF;

  }

  *(pTxMB + 1) = txID;  // write ID

  for (i=0; i<length/4; i++,z+=4) {

    *(pTxMB + 2 + i) =  z<<24 | (z+1)<<16 | (z+2)<< 8 | z+3;      /* Data to be transmitted */

  }

  *pTxMB = (0   // Tx Buffer 0 T0 word

           | 1<<31  // extended Data Length

           | 1<<30  // bit rate switch

           | 0xC<<24    // code = 0xC, TX once

           | 1<<22  // SRR = 1

           | ext<<21    // IDE

           | 0<<20  // RTR = 0

           | dlc<<16);  // DLC

  while (!(CAN_0.IFLAG1.R & 1<<mb)) {};  /* Wait for CAN 0 MB 0 flag */

  CAN_0.IFLAG1.R = 1<<mb;   // clear MB flag

}

/*******************************************************************************

Function Name : ReceiveMsgFD

Engineer      : Petr Stancik

Date          : Jun-22-2021

Parameters    : mb ... MB number used

Modifies      : NONE

Returns       : NONE

Notes         : check if given MB have new message, if yes, read it

Issues        : NONE

*******************************************************************************/

void ReceiveMsgFD(uint32_t mb)

{

  uint8_t j;

  uint32_t dummy,dlc;

  uint32_t *pRxMB = GetMBAddr(mb);

  uint8_t *pRxMBdata = (uint8_t *)(&pRxMB[2]);

  if(CAN_0.IFLAG1.R & 1<<mb)  // if CAN 0 MB flag set

  {

        /* Read CODE, ID, LENGTH, DATA, TIMESTAMP*/

        dummy = *pRxMB;

        RxCODE   = (dummy>>24) & 0xF;

        RxID     = *(pRxMB+1);

        dlc = (dummy>>16) & 0xF;

        /*calculate no. bytes from dlc value*/

        if(dlc < 0x09)

        {

            RxLENGTH = dlc;

        }else if(dlc == 0x9){

            RxLENGTH = 12;

        }else if(dlc == 0xA){

            RxLENGTH = 16;

        }else if(dlc == 0xB){

            RxLENGTH = 20;

        }else if(dlc == 0xC){

            RxLENGTH = 24;

        }else if(dlc == 0xD){

            RxLENGTH = 32;

        }else if(dlc == 0xE){

            RxLENGTH = 48;

        }else{

            RxLENGTH = 64;

        }

        for (j=0; j<RxLENGTH; j++) {

          RxDATA[j] = *pRxMBdata++ ;

        }

        RxTIMESTAMP = dummy & 0xFF;;

        dummy = CAN_0.TIMER.R;      // Read TIMER to unlock message buffers

        CAN_0.IFLAG1.R = 1<<mb;     // clear MB flag

  }

}