LIN Slave code for MPC 5777c

qudgus877 · ‎06-25-2023

Hello, I'm inquiring because I'm having trouble making the LIN Slave code. I've looked at the example code and I'm sending Rx data from LIN Slave around infinite loop with for statement, I want to send and receive Rx data with 100ms routine. May I ask for your advice on what parts of the code I've come up with to fix? Here's the code.

static uint16_t CRC15(const uint32_t bStart, uint8_t data)

{

/* holds the actual CRC code */

static uint32_t crc_rg = 0;

/* used in CRC-15 algorithm */

register uint32_t crcnxt = 0;

/* loop counter */

register int32_t i = 0;

if(CRC15_START == bStart)

{

/* CRC_RG = 0; */

crc_rg = 0;

}

/* crc15 code for 8 input bits, lsb first */

for(i=0;i<8;i++)

{

/* CRCNXT = NXTBIT EXOR CRC_RG(14); */

crcnxt = data ^ (crc_rg >> 14);

crcnxt = (crcnxt & 0x00000001);

/* CRC_RG(14:1) = CRC_RG(13:0);

* CRC_RG(0) = 0; */

crc_rg = (crc_rg << 1); /* left shift by 1 position */

crc_rg = crc_rg & 0x00007FFF;

/* IF CRCNXT THEN

* CRC_RG(14:0) = CRC_RG(14:0) EXOR (4599hex) */

if(crcnxt)

{

crc_rg = (crc_rg ^ 0x00004599);

crc_rg = (crc_rg & 0x00007FFF);

}

/* prepare next bit */

data = (uint8_t)(data >> 1);

}

return (uint16_t)crc_rg;

}

uint32_t fsm = 0;

uint32_t idx = 0;

uint16_t crc15 = 0;

void LIN_Slave_Send_Recevie(uint32_t *check)

{

uint32_t i = 0;

*check = fsm;

switch(fsm)

{

case FSM_RECEIVE_CHARACTERS:

/* wait for a received char

* Break will cause framing error (Stop bit received as 0) */

if(1 == eSCI_B.IFSR1.B.RDRF)

{

eSCI_B.IFSR1.R = 0x2000; /* clear RDRF and FRM */

/* move received char into the memory */

rx_char[idx] = (uint8_t)eSCI_B.SDR.B.RDTD;

/* check Master header */

switch(idx)

{

case 0: /* check 1st received char for Break */

if(0x00 == rx_char[idx])

{

idx = 1;

}

break;

case 1: /* check 2nd received char for Sync */

if(0x55 == rx_char[idx])

{

idx = 2;

}

break;

case 2:

/* check 3rd byte - ID and two ID's parity bits */

/* ID = 0x38

* 0x78 = ID + 2 parity bits

* application specified as LIN Rx frame

* with 4 bytes payload and 2 bytes of CRC */

if(0x78 == rx_char[idx])

{

fsm = FSM_SLAVE_RESPONSE_CRC;

idx = 0;

}

else if(0x34 == rx_char[idx])

{

/* ID = 0x39

* 0x39 = ID + 2 parity bits

* application specified as LIN Tx frame

* with 4 data bytes

* thus 9 bytes received in total

* Break+Sync+ID+Data_bytes+CRC1+CRC2 */

/* receive next data byte */

idx++;

}

break;

default:

/* this part for LIN Tx Frame only

* receive all remaining data bytes and 2 CRC bytes */

idx++;

if(idx>10)

{

fsm = FSM_MASTER_RESPONSE_CRC;

idx = 0;

}

break;

}

break;

case FSM_SLAVE_RESPONSE_CRC:

/* disable the receiver during Slave response */

eSCI_B.CR1.B.RE = 0;

/* compute CRC-15 for the Slave response */

crc15 = CRC15(CRC15_START, 0x78); /* ID (including ID's parity) */

for(i=0; i<8; i++)

{

crc15 = CRC15(0, tx_char[i]); /* data0..data7 */

}

/* MSBit of the TX'ed CRC must be high */

crc15 = (uint16_t)(crc15 | 0x8000);

/* CRC1 is LSByte of the actual CRC code */

tx_char[8] = (uint8_t)crc15;

/* CRC2 is MSByte of the actual CRC code */

tx_char[9] = (uint8_t)(crc15 >> 8);

fsm = FSM_SLAVE_RESPONSE_TX;

break;

case FSM_SLAVE_RESPONSE_TX:

/* Transmit Slave response */

if(1 == eSCI_B.IFSR1.B.TDRE)

{

eSCI_B.SDR.B.RDTD = (uint16_t)(0x00FF & tx_char[idx]);

eSCI_B.IFSR1.B.TDRE = 0x8000;

/* last CRC byte TX'ed */

if(5 == idx)

{

fsm = FSM_FRAME_COMPLETE;

}

/* Tx next byte */

idx++;

}

break;

case FSM_FRAME_COMPLETE:

idx = 0; /* reset array index */

fsm = FSM_RECEIVE_CHARACTERS;

/* re-enable the receiver */

eSCI_B.CR1.B.RE = 1;

break;

case FSM_MASTER_RESPONSE_CRC:

/* LIN Tx Frame - data and CRC received from Master */

/* compute CRC-15 for the received Master response */

crc15 = CRC15(CRC15_START, 0x34); /* ID (including ID's parity) */

for(i=3; i<11; i++)

{

crc15 = CRC15(0, rx_char[i]); /* data0..data7 */

}

/* MSBit of the computed CRC must be high */

crc15 = (uint16_t)(crc15 | 0x8000);

/* compare CRC1 with LSByte */

if(rx_char[11] == (uint8_t)crc15)

{

/* compare CRC2 with MSByte */

if(rx_char[12] == (uint8_t)(crc15 >> 8))

{

/* received data are correct */

fsm = FSM_FRAME_COMPLETE;

}

else

{

fsm = FSM_FRAME_COMPLETE;

//fsm = FSM_ERROR;

}

else

{

fsm = FSM_FRAME_COMPLETE;

//fsm = FSM_ERROR;

}

break;

case FSM_ERROR:

break;

}

Currently, it is not possible to send and receive Rx data.

Thanks for your help

PetrS · ‎06-26-2023

Hi,

there is no HW support for LIN slave in this MCU and all must be done by SW. There are some code posted in https://community.nxp.com/t5/MPC5xxx/5668G-Lin-slave/m-p/996910 but probably this is the one you are referring to. We have no other example for this.
LIN slave is responding to LIN header sent from master. So do you have connection to some master and it is sending or requesting data? Do you see correct header received on your slave? Do you have LIN transceiver active and set TX RX pins properly. What about baudrate setting, same as master one?

BR, Petr