NXP S32K148 Evaluation Board UART Receive Fails

[ParthiVenkat]

I am working with NXP S32K148 Evaluation Board and developing a sample program for UART transmit and receive at the Baud rate of 115200.

Taken the Project Example S32K148_Project_LPUART and I have reconfigured the baud rate to 115200 with the following configuration

PCC->PCCn[PCC_LPUART1_INDEX] &= ~PCC_PCCn_CGC_MASK; // Ensure clk disabled for config
PCC->PCCn[PCC_LPUART1_INDEX] |= PCC_PCCn_PCS(0b110) // Source clock for LPUART1 is SPLLDIV2_CLK 
| PCC_PCCn_CGC_MASK; // Enable clock for LPUART1 regs

LPUART1->BAUD = LPUART_BAUD_SBR(0xC) /* Initialize for 115200 baud, 1 stop: */
                                 | LPUART_BAUD_OSR(28); /* SBR=12 (0xC): baud divisor = 40M/115200/29 = ~12 */

                               /* OSR=28: Over sampling ratio = 28+1=29 */
                               /* SBNS=0: One stop bit */
                               /* BOTHEDGE=0: receiver samples on the rising edge*/
                               /* M10=0: Rx and Tx use 7 to 9 bit data characters */
                               /* RESYNCDIS=0: Resync during rec'd data word supported */
                               /* LBKDIE, RXEDGIE=0: interrupts disable */
                               /* TDMAE, RDMAE, TDMAE=0: DMA requests disabled */
                               /* MAEN1, MAEN2,  MATCFG=0: Match disabled */

LPUART1->CTRL = LPUART_CTRL_RE_MASK
                                 |LPUART_CTRL_TE_MASK; /* Enable transmitter & receiver, no parity, 8 bit char: */

                               /* RE=1: Receiver enabled */
                               /* TE=1: Transmitter enabled */

With the above configuration I can able to transmit data from Evaluation Board to PC(using TTL converter).

But when I tried to UART receive data from PC to Evaluation Board is not working. The following is the code to receive the char

char LPUART1_receive_char(void) { /* Function to Receive single Char */
  char receive;
  while((LPUART1->STAT & LPUART_STAT_RDRF_MASK)>>LPUART_STAT_RDRF_SHIFT==0);
  /* Wait for received buffer to be full */
  receive= LPUART1->DATA; /* Read received data*/
  return receive;
}

Data is sent from the PC to LPUART1_RX(PTC6), but the cursor is not passing the while statement LPUART1->STAT value remained at 0xC00000.

Can you please help me on this where am missing.

[ParthiVenkat]

Resolved. By default the code have been configured to use LPUART1, updated the configuration to use LPUART0 and the code works fine as expected.

[Robin_Shen]

It looks like you are using the S32K148_Project_LPUART
example in S32DS Example Projects for S32K1xx.
If you use the lpuart_echo_s32k148 example in S32SDK S32K1xx RTM v3, it will be much easier to use Processor Expert to modify the clock source and baud rate.

Best Regards,
Robin
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[ParthiVenkat]

Thank you Robin_Shen for your reply.

I think, Baud rate configuration is not the primary issue here.

Because even with S32K148_Project_LPUART code default baud rate of 9600, UART receive is not working.

It is not exiting the while loop

while((LPUART1->STAT & LPUART_STAT_RDRF_MASK)>>LPUART_STAT_RDRF_SHIFT==0);

Please help me on this.

[Robin_Shen · Accepted solution]

I test your configuration on S32K148EVB. If I send char one by one, then it's ok. But if I send several bytes at a time, then it will not exiting the while loop due to the Receiver Overrun Flag.

You may need to modify the receive function by refer the API of SDK.

[LBLDT]

I have exactly the same problem except I configured correctly the UART, how can I overcome this OR flag issue ?