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SK-AM64B: Quality Alert / Technical Support Request: Multiple UART Failures on SK-AM64B Evaluation Module

Shikha .
Prodigy 30 points

Part Number: SK-AM64B

Dear Texas Instruments Support Team,

We recently purchased a total of four SK-AM64B/TI development boards through a third-party vendor, Seutes Technologies. Out of these four boards, three have been found to be defective.

The issue observed across the affected boards is that the UART port is not functioning. This appears to be a recurring problem, as multiple units exhibit the same defect. We would like to understand the possible cause of this issue and whether it could be related to a manufacturing defect, batch issue, or any known hardware/software concern.

Additionally, we purchased two of these boards on 26/12/2025 and raised a complaint with the vendor (Seutes Technologies). However, we have not received a satisfactory response or resolution from them so far.

Given that this is a Texas Instruments product, we request your assistance in:

  • Identifying the root cause of the UART issue
  • Advising any troubleshooting steps or fixes
  • Guiding us on how to proceed with repair, replacement, or warranty support

We would appreciate your prompt support in resolving this matter, as it is impacting our development work.

Thank you for your assistance.

Shikha

Contact: shikha@cdac.in

Centre for Development of Advanced Computing (C-DAC)

Centre in North East (CINE)

R and D extension of Silchar,IIT guwahati Research park ,Guwahati, Assam 

Ministry of Electronics and Information Technology

Government of India

  • 0
    TI__Genius 16020 points

    Hi Shikha,

    This is not a known issue, and I am not aware of other reports of similar issues.  Here's a few questions to help debug-- 

    1. Is the LD16 LED (Power good LED) is glowing after power on the board?
    2. Were you able to see the USB Serial port under Ports (COM &LPT) on the Device manager?
    3. If you are able to see the port on device manager and configured serial console Terra term, have you tried booting TI Linux SDK and seeing any LED toggling on board and not seeing any prints on console?  This make sure that the board is working and only UART Bridge is not working.
    4. What is the serial number of the boards?  Can you please also share pictures of the boards?

    Regards,

    Melissa

  • 0 in reply to melissaw
    Prodigy 30 points

    Hi Melissa,

    Thank you for your response.

    Please find below the details requested:

    1. LD16 LED Status: Yes, the LD16 (Power Good LED) is glowing after powering on the board.
    2. USB Serial Port Detection: No, the USB Serial port is not listed under Ports (COM & LPT) in the Device Manager.
    3. Boot Test with TI Linux SDK: We have not attempted this test, as the USB serial port is not being detected on the system.
    4. Serial Numbers of Affected Boards:
      • SL# 37221000249
      • SL# 37221000143
      • SL# 27231000934

    Please let us know the next steps for further debugging or resolution.

    Regards,

    Shikha

    Contact: shikha@cdac.in

  • 0 in reply to Shikha .
    TI__Genius 16020 points

    Hi Shikha,

    1. LD16 LED Status: Yes, the LD16 (Power Good LED) is glowing after powering on the board.  Power is good on the board.
    2. USB Serial Port Detection: No, the USB Serial port is not listed under Ports (COM & LPT) in the Device Manager.  My primary suspect is driver issue. I would recommend them to follow these instructions:- https://dev.ti.com/tirex/explore/node?node=A__ASbsvXLcIie6AhqNHYKxUw__PROCESSORS-DEVTOOLS__FUz-xrs__LATEST   Refer Connecting with Windows section :- If your Windows PC doesn't recognize the device, download and install the driver from here.
    3. Boot Test with TI Linux SDK: We have not attempted this test, as the USB serial port is not being detected on the system.  Can you try booting with default SDK which is available on TI.com and see whether you see any heart beat LED toggling.

    Regards,

    Melissa

  • 0 in reply to melissaw
    Prodigy 30 points

    Hi Melissa,

    Thank you for your continued support.

    We would like to provide an update along with additional observations:

    • The power supply being used for the EVM has been verified and fully complies with the recommended specifications mentioned in the guidelines.
    • We have carefully followed all the troubleshooting steps shared by your team; however, the issue still persists.
    • Currently, LEDs LD16, LD2, and LD13 are glowing, indicating that the board is powered and partially operational. However, LD18 (UART LED) is not glowing, which appears to be the main concern.
    • When the board is connected to the PC via USB, no serial port is detected in the Device Manager.
    • Find the relevant screenshots for your reference.

     

    Based on these observations, it appears that the micro-USB (UART bridge) interface is not functioning. Since this issue has occurred across multiple boards without any changes in setup or configuration, it seems unlikely to be related to drivers or the host system.

    We kindly request your guidance on the next steps for further diagnosis. If this indicates a potential hardware issue, please advise on the process for repair or replacement (RMA).

    We appreciate your assistance and look forward to your response.

    Regards,

    Shikha

    Contact: shikha@cdac.in

  • 0 in reply to Shikha .
    TI__Genius 16020 points

    Hi Shikha,

    Thanks for the additional observations.  Yes, the fact that LD18 is not glowing indicates that no power is available for CP2105 (UART Bridge).  Can you measure the voltage on TP76?

    Regards,

    Melissa

  • 0 in reply to melissaw
    Prodigy 30 points

    Hi Melissa,

    Thank you for your guidance.

    As requested, we have measured the voltage at TP76 for the affected boards. Please find the observations below:

    1. SL# 37221000249 – 4.90V (While connecting the USB cable, LD18 initially glows briefly and then turns off.)
    2. SL# 37221000143 – 5.19V
    3. SL# 27231000934 – 5.19V

    Based on these measurements, the supply at TP76 appears to be within range. However, LD18 is not staying ON (or not glowing at all in other cases), indicating that the CP2105 (UART Bridge) is still not functioning as expected.

    Kindly advise on the next steps for further debugging or let us know if this points to a possible hardware issue requiring replacement.

    Regards,

    Shikha

    Contact: shikha@cdac.in