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DM368 UART issue in RS485 mode

Eason Wang
Genius 13460 points

Hi ,

My customer find that when set UART in RS485 mode(The default mode is RX), the TXD often transfer one more bit. 

They compared UART status register 0x01D06014, when uart is ok, the reg value is 0x00->0x20->0x60. when in abnormal, the reg value is always 0x60.

Another finding is, the time between sending the TX cmd to uart and uart send out data is very long, which is  obviously abnormal (baud rate 9600, 4Byte data, cost 100ms!)


Could you give some advice?

Thanks & Best regards,

Eason

  • 0
    TI__Genius 13460 points

    I have checked w/ customer, when they test the UART, the CPU loading was normal. So it should not because of the UART thread was waiting for CPU free.

    Also I asked customer to check if the uart settings were modified by unexpected operation (use HW watchpoint, to check the LCR, the start/stop bit, the data length register)

    The issue comes random, I have no idea why this happens.

    So far, the issue is only observed in RS485 mode, which require T/R mode change by 1 signal line. So We doubt if the mode change has some kind of delay of mis-match

    BR,

    Eason