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AM2431: AM2431: UART3 RX Not Working on D16, TX Working Fine on E16

Manikandan Velayudham
Prodigy 250 points

Part Number: AM2431
Other Parts Discussed in Thread: SYSCONFIG

Hi TI Experts,

I am using AM2431BSDGHIALVR in a custom board design. We have configured 4 UART channels, each connected through an RS422 transceiver to communicate with an external board.

One UART channel is not working as expected.

Device: AM2431BSDGHIALVR
UART Instance: UART3
RX Pin: D16
TX Pin: E16

Issue

UART3 transmission is working correctly. Data transmitted from UART3_TX on E16 is received properly on the external board.

However, the AM2431 is not able to receive any data on UART3_RX on D16.

Debug Tests Performed

  1. RS422 communication test
    • UART3 TX path is working.
    • External board receives data correctly.
    • UART3 RX path is not receiving data.
  2. Direct loopback test
    • Removed/bypassed the RS422 transceiver.
    • Shorted UART3 TX and RX lines directly.
    • Loopback test failed on UART3.
  3. GPIO test on D16
    • Configured D16 as GPIO input/output.
    • Verified signal toggling and manual input sensing.
    • Pin is alive and soldering/BGA connection appears to be proper.
    • Issue is seen only when D16 is configured as UART3_RX.

Additional Information

  • The same SDK-based UART loopback test code works correctly on other UART channels.
  • The UART configuration flow is the same for all working channels.
  • Only UART3 RX is failing.
  • Schematic snippet and SDK test files are attached for reference.

Could you please help check whether there are any specific pinmux, pad configuration, input enable setting, or known limitation related to UART3_RX on D16 for AM2431?

SysConfig Settings for Problematic UART

 

uart4.inputClkFreq     = 160000000;

uart4.baudRate         = 10000000;

uart4.sdkInfra         = "LLD";

uart4.readCallbackFxn  = "Callback_rx4";

uart4.writeCallbackFxn = "Callback_tx4";

uart4.$name            = "CONFIG_RS422_4";

uart4.intrEnable       = "DISABLE";

uart4.UART.$assign     = "USART3";

uart4.UART.RXD.pu_pd   = "pu";

uart4.UART.RXD.$assign = "UART1_CTSn";

uart4.UART.TXD.$assign = "UART1_RTSn";

 

Please let me know if you need any further details or files to identify and resolve this issue.  

Is there any known limitation or issue with UART3 RX on AM243?

 

Thanks,

Manikandan V

  • 0
    TI__Guru 57925 points

    Hi,

    I am not sure if the UART Baud rate settings are correct here. Could you please try with a default configuration which is mentioned as follows:

    I would have you try with blocking mode and basically the setting as shown above in the screenshot.

    Let me know if it works for D16 --> UART RXD? 

    Also if you can share a screenshot of the UART code which does the receive part in your application, that would be really helpful. Basically the part that does Uart Transaction Init and the UART_read call.

    Looking forward to your response.

    Best regards,

    Vaibhav

  • 0 in reply to Vaibhav Kumar
    Prodigy 20 points

    Hi Vaibhav,

    We tried reflashing the same SBL files and rebooting the board. After that, UART3 RX started working properly without any hardware or pinmux changes.

    I have attached the SBL files for your reference.

    /cfs-file/__key/communityserver-discussions-components-files/791/5657.sbl_5F00_null.zip

    Could you please let us know what could cause a specific UART RX channel to behave like this?


    Thanks,
    Ganesh M

  • 0 in reply to Ganesh Mohan
    TI__Guru 57925 points

    Hi Ganesh,

    What you sent me is a release image/just a binary from which I am not able to figure out the SysConfig settings of your SBL project.

    But, I am not sure how do we go about isolating this one, as its first of a kind for me as well. The UART RX issue which you encountered, are you able to face this again? If you face this again further down the development, please keep a track of pre-failure steps, so then we can look at the possible causes.

    But looks like a simple reflashing worked charm for you. Let me know if you face this again and note down the steps prior to the failure.

    Regards,

    Vaibhav