RTOS/EVMK2H: I can't read a 0xff byte over the UART

Hi Yordan,

Thank you for your attention. A member of our project found that the following code cannot distinguish between the error code(-1) and 0xff data.

"C:\ti\pdk_am57xx_1_0_10\packages\ti\csl\src\ip\uart\V1\priv\uart.c"

967 int8_t UARTCharGetNonBlocking(uint32_t baseAddr)
968 {
969     uint32_t lcrRegValue = 0;
970     int8_t   retVal      = -((int8_t) 1);
971
972     /* Switching to Register Operational Mode of operation. */
973     lcrRegValue = UARTRegConfigModeEnable(baseAddr, UART_REG_OPERATIONAL_MODE);
974
975     /* Checking if the RX FIFO(or RHR) has atleast one byte of data. */
976     if ((uint32_t) UART_LSR_RX_FIFO_E_RX_FIFO_E_VALUE_0 !=
977         (HW_RD_REG32(baseAddr + UART_LSR) &
978          UART_LSR_RX_FIFO_E_MASK))
979     {
980         uint32_t tempRetVal = HW_RD_REG32(baseAddr + UART_RHR);
981         retVal = ((int8_t) tempRetVal);
982     }
983
984     /* Restoring the value of LCR. */
985     HW_WR_REG32(baseAddr + UART_LCR, lcrRegValue);
986
987     return retVal;
988 }

Best regards,

Takashi

Hi Prabhu-san,

Thank you for your reply. We set the UART parameters as follows:

params.readDataMode = UART_DataMode::UART_DATA_BINARY;
params.writeDataMode = UART_DataMode::UART_DATA_BINARY;
params.readReturnMode = UART_ReturnMode::UART_RETURN_FULL;
params.readEcho = UART_Echo::UART_ECHO_OFF;

Therefore, we cannot find any difference from your parameters in your previous reply. In addition, we found that UART_v1_readData() in UART_vi.c is always calling UARTCharGetNonBlocking() regardless of the above parameters.

That's why, we think that the UARTCharGetNonBlocking() does not have enough I/F to return the read data with 8-bit and the error code by a return value with int8_t.

Best regards,

Takashi

Rahul

I have tried above updating to test, but when I call API UART_read, always and continuously get 0xFF even though PC has not sent 0xFF. please check and give an available  workaround, thanks.

Leonard