DRA78: Processor SDK RTOS Automotive - UART driver cannot receive 0xFF bytes

Manfred Becker

Part Number: DRA78

There seems to be an error in the UART driver for DRA7xx devices provided with Processor SDK RTOS Automotive 4_03_00_05 and the related pdk_dra7xx_1_0_10. The function UARTCharGetNonBlocking returns -1 or 0xFF in error case (If the RX FIFO(or RHR) was found to have at least one byte of data, then this API reads and returns that byte. Else it returns -1). That condition is finally used by function UART_v1_readData to terminate the UART reception.

static inline int32_t UART_v1_readData(UART_Handle handle, int32_t size)
{
    int32_t             readIn;
    UART_V1_Object     *object;
    UART_HwAttrs const *hwAttrs;

    object = (UART_V1_Object*)handle->object;
    hwAttrs = (UART_HwAttrs const *)handle->hwAttrs;
    readIn = (int32_t)UARTCharGetNonBlocking(hwAttrs->baseAddr);

    /* Receive chars until empty or done. */
    while ((size != (int32_t)(0)) && (readIn != (-((int32_t)1))))
.....

This termination conditions prevents the UART from receiving any data streams containing 0xFF byte data.

Would be great if that could be fixed in one of the next PDK releases.

Best regards,

Manfred

over 7 years ago

0 Stephen Molfetta over 7 years ago

TI__Expert 5725 points

Hi Manfred,

This issue was reported in the internal JIRA PRSDK-4529 and fixed recently. There is no DRA7xx PDK update planned right now, but an official fix has been pushed to the externally mirrored Git repo: http://git.ti.com/keystone-rtos/uart-lld/commit/fc99ad761cddfbb88dbb72fdd64d0b20594004e5

If this isn't a major issue for now, hopefully you can avoid the 0xFF byte in the application or can find an acceptable workaround. Otherwise, if you have a major issue with this, we can work to find a way to get this to apply on top of the 1.0.10 PDK (likely won't apply cleanly as-is).

Thanks,
Stephen

0 Manfred Becker over 7 years ago in reply to Stephen Molfetta

TI__Expert 4570 points

Hi Stephen,

it's not that urgent. A customer found this problem but he already modified the source code to implement a workaround.

Regards,
Manfred

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DRA78: Processor SDK RTOS Automotive - UART driver cannot receive 0xFF bytes