MPC5554 FlexCAN Problem

EmbeddedApe — Fri, 19 Mar 2010 21:59:55 GMT

I have a code written for enabling FlexCAN on MPC5554. I am transferring data message from CAN_A to CAN_B at around 100KHz. To validate the same code, I have connected CANH1 to CANH2 and CANL1 to CANL2 and same has been connected to oscilloscope probes for observing the data. The problem here is " Data never stops transmitting".

I can see data keep on transmitting again and again. Even after stopping the CodeWarrior debugger, the data is still transmitting. Please find the code below for your reference. I tried the same using FREEZE Mode, Normal mode and Loopback mode. in all cases the same issue.

Please suggest me of there is any problem in my code , register configurations.

#include "flexcan_mpc5554.h"

uint32_t RxCODE; /* Received message buffer code */
uint32_t RxID; /* Received message ID */
uint32_t RxLENGTH; /* Received message number of data bytes */
uint8_t RxDATA[8]; /* Received message data string*/
uint32_t RxTIMESTAMP; /* Received message time */

void initCAN_A (void) {
uint8_t i;
//CAN_A.MCR.R = 0x5000003F; /* Put in Freeze Mode & enable all 64 msg buffers*/
CAN_A.MCR.R = 0x1000003F; /* Put in Normal & enable all 64 msg buffers*/ /* Normal Mode*/

// while(CAN_A.MCR.B.FRZ == 0) { } ;

CAN_A.CR.R = 0x04DB0006; /* Configure for 8MHz OSC, 100kHz bit time */

for (i=0; i<64; i++) {
CAN_A.BUF[i].CS.B.CODE = 0; /* Inactivate all message buffers */
}

CAN_A.BUF[0].CS.B.CODE = 8; /* Message Buffer 0 set to TX INACTIVE */

SIU.PCR[83].R = 0x062C; /* MPC555x: Configure pad as CNTXA, open drain */
SIU.PCR[84].R = 0x0500; /* MPC555x: Configure pad as CNRXA */
CAN_A.MCR.R = 0x0000003F; /* Negate FlexCAN A halt state for 64 MB */

//while (CAN_A.MCR.B.FRZACK == 0) {};

}

void initCAN_B (void) {
  uint8_t i;

  //CAN_B.MCR.R = 0x5000003F; /* Put in Freeze Mode & enable all 64 msg buffers*/
  CAN_B.MCR.R = 0x1000003F; /* Put in Normal & enable all 64 msg buffers*/ /*Normal Mode*/

  CAN_B.CR.R = 0x04DB0006; /* Configure for 8MHz OSC, 100kHz bit time */

  for (i=0; i<64; i++) {
   CAN_B.BUF[i].CS.B.CODE = 0; /* Inactivate all message buffers */
  }

  CAN_B.BUF[4].CS.B.IDE = 0; /* MB 4 will look for a standard ID */
  CAN_B.BUF[4].ID.B.STD_ID = 555; /* MB 4 will look for ID = 555 */
  CAN_B.BUF[4].CS.B.CODE = 4; /* MB 4 set to RX EMPTY */
  CAN_B.RXGMASK.R = 0x1FFFFFFF; /* Global acceptance mask */


  SIU.PCR[87].R = 0x0E2C; /* MPC555x: Configure pad as CNTXC, open drain */
  SIU.PCR[88].R = 0x0D00; /* MPC555x: Configure pad as CNRXC */
  CAN_B.MCR.R = 0x0000003F; /* Negate FlexCAN B halt state for 64 MB */

}

void TransmitMsg (void) {
uint8_t i;

/* Assumption: Message buffer CODE is INACTIVE */
const uint8_t TxData[] = {"Hello World!! \n\r"}; /* Transmit string*/

CAN_A.BUF[0].CS.B.IDE = 0; /* Use standard ID length */
CAN_A.BUF[0].ID.B.STD_ID = 555; /* Transmit ID is 555 */
CAN_A.BUF[0].CS.B.RTR = 0; /* Data frame, not remote Tx request frame */
CAN_A.BUF[0].CS.B.LENGTH = sizeof(TxData) -1 ; /* # bytes to transmit w/o null */

for (i=0; i<sizeof(TxData); i++) {
  CAN_A.BUF[0].DATA.B[i] = TxData[i]; /* Data to be transmitted */
}

  CAN_A.BUF[0].CS.B.SRR = 1; /* Tx frame (not req'd for standard frame)*/
  CAN_A.BUF[0].CS.B.CODE =0xC; /* Activate msg. buf. to transmit data frame */
}

void ReceiveMsg (void) {
uint8_t j;
uint32_t dummy;

while (CAN_B.IFRL.B.BUF04I == 0) {}; /* MPC555x: Wait for CAN B MB 4 flag */

  RxCODE = CAN_B.BUF[4].CS.B.CODE; /* Read CODE, ID, LENGTH, DATA, TIMESTAMP*/
  RxID = CAN_B.BUF[4].ID.B.STD_ID;
  RxLENGTH = CAN_B.BUF[4].CS.B.LENGTH;

  for (j=0; j<RxLENGTH; j++) {
   RxDATA[j] = CAN_B.BUF[4].DATA.B[j];
  }

  RxTIMESTAMP = CAN_B.BUF[4].CS.B.TIMESTAMP;
  dummy = CAN_B.TIMER.R; /* Read TIMER to unlock message buffers */

  /* Use 1 of the next 2 lines: */
  /*CAN_B.IFLAG1.R = 0x00000010;*/ /* MPC551x: Clear CAN C MB 4 flag */

  CAN_B.IFRL.R = 0x00000010; /* MPC555x: Clear CAN C MB 4 flag */

}

void FlexCAN_program()
{
volatile uint32_t IdleCtr = 0;
initCAN_B(); /* Initialize FLEXCAN B & one of its buffers for receive*/
initCAN_A(); /* Initialize FlexCAN A & one of its buffers for transmit*/
TransmitMsg(); /* Transmit one message from a FlexCAN A buffer */
ReceiveMsg(); /* Wait for the message to be received at FlexCAN B */

while (1) { /* Idle loop: increment counter */
IdleCtr++;
}

}

Re: MPC5554 FlexCAN Problem

EmbeddedApe — Wed, 07 Apr 2010 04:13:58 GMT

I fixed the prorblem. Proper assignment of PCR registers, around 100ns delay before data transfer fixes the IFRL interrupt bit assertion issue. Please ping me if any one has a similar issues.

Thanks for Freescale's Mr. Alexander for all his time.

Re: MPC5554 FlexCAN Problem

JulienP — Fri, 17 Dec 2010 05:32:19 GMT

Hello sir,

I'm actually running into kind of the same problem. I'm working with a MCF5235 uC that communicates with another uC using CAN bus. Sometimes, my uC is transmitting for ever, depending of the datas I'm sending. For example:

- ID = 0x18DAEEFB DATA = 0x02-10-7E-FF-FF-FF-FF-BB <= Works great!

- ID = 0x18DAEEFB DATA = 0x02-10-7E-FF-FF-FF-FF-CC <= Transmitting for ever!

How did you manage to fix your bug please?

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