To set the RTR bit in Rx buffer in s32k144

[sathyamoorthy]

Hi ,I have doubt in RTR that how to set the RTR  bit in s32k144 and how to receive the RTR request and sent response? can u kindly help me in this.

void FLEXCAN0_init(void) {
#define MSG_BUF_SIZE 4 /* Msg Buffer Size. (CAN 2.0AB: 2 hdr + 2 data= 4 words) */
uint32_t i=0;

PCC->PCCn[PCC_FlexCAN0_INDEX] |= PCC_PCCn_CGC_MASK; /* CGC=1: enable clock to FlexCAN0 */

CAN0->MCR |= CAN_MCR_MDIS_MASK; /* MDIS=1: Disable module before selecting clock */
CAN0->CTRL1 &= ~CAN_CTRL1_CLKSRC_MASK; /* CLKSRC=0: Clock Source = oscillator (8 MHz) */

CAN0->MCR &= ~CAN_MCR_MDIS_MASK; /* MDIS=0; Enable module config. (Sets FRZ, HALT)*/
while (!((CAN0->MCR & CAN_MCR_FRZACK_MASK) >> CAN_MCR_FRZACK_SHIFT)) {}
/* Good practice: wait for FRZACK=1 on freeze mode entry/exit */
CAN0->CTRL1 = 0x00DB0006; /* Configure for 500 KHz bit time */
/* Time quanta freq = 16 time quanta x 500 KHz bit time= 8MHz */
/* PRESDIV+1 = Fclksrc/Ftq = 8 MHz/8 MHz = 1 */
/* so PRESDIV = 0 */
/* PSEG2 = Phase_Seg2 - 1 = 4 - 1 = 3 */
/* PSEG1 = PSEG2 = 3 */
/* PROPSEG= Prop_Seg - 1 = 7 - 1 = 6 */
/* RJW: since Phase_Seg2 >=4, RJW+1=4 so RJW=3. */
/* SMP = 1: use 3 bits per CAN sample */
/* CLKSRC=0 (unchanged): Fcanclk= Fosc= 8 MHz */
for(i=0; i<128; i++ ) { /* CAN0: clear 32 msg bufs x 4 words/msg buf = 128 words*/
CAN0->RAMn[i] = 0; /* Clear msg buf word */
}
for(i=0; i<16; i++ ) { /* In FRZ mode, init CAN0 16 msg buf filters */
CAN0->RXIMR[i] = 0xFFFFFFFF; /* Check all ID bits for incoming messages */
}
CAN0->RXMGMASK = 0xFFFFFFFF; /* Global acceptance mask: check all ID bits */

// CAN0->RAMn[ 0*MSG_BUF_SIZE + 0] = 0x0C400000 | 8 <<CAN_WMBn_CS_DLC_SHIFT;
CAN0->RAMn[ 4*MSG_BUF_SIZE + 0] = 0x04000000; /*0000 0100 0101 0000 0000 0000 0000 0000 Msg Buf 4, word 0: Enable for reception */
/* EDL,BRS,ESI=0: CANFD not used */
/* CODE=4: MB set to RX inactive */
/* IDE=0: Standard ID */
/* SRR, RTR, TIME STAMP = 0: not applicable */
// CAN0->RAMn[ 0*MSG_BUF_SIZE + 0] = 0x0C500000 | 8 <<CAN_WMBn_CS_DLC_SHIFT;
#ifdef NODE_A /* Node A receives msg with std ID 0x511 */
CAN0->RAMn[ 4*MSG_BUF_SIZE + 1] = 0x14440000; /* Msg Buf 4, word 1: Standard ID = 0x111 */
#else /* Node B to receive msg with std ID 0x555 */
CAN0->RAMn[ 4*MSG_BUF_SIZE + 1] = 0x15540000; /* Msg Buf 4, word 1: Standard ID = 0x555 */
#endif
/* PRIO = 0: CANFD not used */
CAN0->MCR = 0x0000001F; /* Negate FlexCAN 1 halt state for 32 MBs */
while ((CAN0->MCR && CAN_MCR_FRZACK_MASK) >> CAN_MCR_FRZACK_SHIFT) {}
/* Good practice: wait for FRZACK to clear (not in freeze mode) */
while ((CAN0->MCR && CAN_MCR_NOTRDY_MASK) >> CAN_MCR_NOTRDY_SHIFT) {}
/* Good practice: wait for NOTRDY to clear (module ready) */
}

void FLEXCAN0_transmit_msg(uint32_t sndId,uint8_t *pdata) { /* Assumption: Message buffer CODE is INACTIVE */

CAN0->IFLAG1 = 0x00000001; /* Clear CAN 0 MB 0 flag without clearing others*/

CAN0->RAMn[ 0*MSG_BUF_SIZE + 2] = 0xA5112233; /* MB0 word 2: data word 0 */
CAN0->RAMn[ 0*MSG_BUF_SIZE + 3] = 0x44556677; /* MB0 word 3: data word 1 */

#ifdef NODE_A
// CAN0->RAMn[ 0*MSG_BUF_SIZE + 1] = 0x15540000; /* MB0 word 1: Tx msg with STD ID 0x555 */
CAN0->RAMn[ 0*MSG_BUF_SIZE + 1] = sndId << 18; /* MB0 word 1: Tx msg with STD ID 0x555 */
#else
CAN0->RAMn[ 0*MSG_BUF_SIZE + 1] = 0x14440000; /* MB0 word 1: Tx msg with STD ID 0x511 */
#endif
CAN0->RAMn[ 0*MSG_BUF_SIZE + 0] = 0x0C400000 | 8 <<CAN_WMBn_CS_DLC_SHIFT; /* MB0 word 0: */
/* EDL,BRS,ESI=0: CANFD not used */
/* CODE=0xC: Activate msg buf to transmit */
/* IDE=0: Standard ID */
/* SRR=1 Tx frame (not req'd for std ID) */
/* RTR = 0: data, not remote tx request frame*/
/* DLC = 8 bytes */
}

void FLEXCAN0_receive_msg(uint8_t newDat[8],uint32_t * msgId) { /* Receive msg from ID 0x556 using msg buffer 4 */
uint8_t j;
uint32_t dummy;

RxCODE = (CAN0->RAMn[ 4*MSG_BUF_SIZE + 0] & 0x07000000) >> 24; /* Read CODE field */
// RxID = (CAN0->RAMn[ 4*MSG_BUF_SIZE + 1] & CAN_WMBn_ID_ID_MASK) >> CAN_WMBn_ID_ID_SHIFT ;
*msgId =((CAN0->RAMn[ 4*MSG_BUF_SIZE + 1] & 0x1ffc0000UL) >> 18) ;

RxLENGTH = (CAN0->RAMn[ 4*MSG_BUF_SIZE + 0] & CAN_WMBn_CS_DLC_MASK)>>CAN_WMBn_CS_DLC_SHIFT ;

// RxLENGTH = (CAN0->RAMn[ 4*MSG_BUF_SIZE + 0] & CAN_WMBn_CS_DLC_MASK) >>CAN_WMBn_CS_DLC_MASK ;

for (j=0; j<2; j++) { /* Read two words of data (8 bytes) */
RxDATA[j] = CAN0->RAMn[ 4*MSG_BUF_SIZE + 2 + j];
}

RxTIMESTAMP = (CAN0->RAMn[ 0*MSG_BUF_SIZE + 0] & 0x000FFFF);
dummy = CAN0->TIMER; /* Read TIMER to unlock message buffers */
CAN0->IFLAG1 = 0x00000010; /* Clear CAN 0 MB 4 flag without clearing others*/

}

[PetrS]

Hi,

please refer to chapter 55.3.10.4 Remote frames of the device RM.

BR, Petr

[sathyamoorthy]

hi,

Do you have any sample code to set RTR bit in Rx buffer.

[PetrS]

Hi,

if you want to configure an MB to recognize remote request frame and send a response automatically to that, then simply fill the MB with matching ID and required payload to be sent. Then set the MB's CODE field to 0xA.

If you want to send remote request frame just set RTR bit of the MB and then set MB's CODE to 0xC.

BR, Petr