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DM814x UARTx_RXD swing between 0.8V~3.3V

Eason Wang
Genius 13460 points

Hi ,

My customer use USB-UART cable to test the UART1(AG2,AF4) UART2(L25,N23)

They find that the TXD is OK but the RXD has issue.

By measuring the signals, they found the RXD swing between 0.8~3.3V, which is out of spec.

They have checked the pinmux(aslo the PU/PD setting) .

Could you give some advice on this issue?

BR

Eason

  • 0
    TI__Guru**** 170625 points

    Hi Eason,

    Eason Wang said:
    My customer use USB-UART cable to test the UART1(AG2,AF4) UART2(L25,N23)

    Are you trying to use different UART (UART1/2) for console than the default one (UART0)? IF yes, refer to the below wiki pages:

    http://processors.wiki.ti.com/index.php/TI81xx_PSP_Porting_Guide#Using_different_UART_than_the_default_EVM_configuration_as_console

    UART1_RXD signal can be selected in 2 device pins: F27 and AF24. Make sure you are not selecting UART1_RXD input on both pins. The DM814x device does not support selecting input signals on more than one pin.

    Regards,
    Pavel

  • 0 in reply to Pavel Botev
    TI__Genius 13460 points

    Thanks Pavel.

    The root cause was there are some HW design issues on PCB. After fixing those issues, UART behavior came back to normal.

    Your suggestion is very helpful.

    Regards,

    Eason