SK-AM64B: AM64x SK (PROC100A) - Debug console UART COM port no longer detected

Hello User,

Thank you for the query.

승호 이 said:

When I first received the board, the debug console worked correctly — connecting the micro-USB cable to the UART port enumerated the CP2105 and two COM ports appeared on my host PC as expected.

Checking if you have been using this for a long time.

Can you confirm if all the supplies are available and other functions on the board are working.

I am checking parallelly with the team.

Regards,

Sreenivasa

Hi Sreenivasa,

Thank you for the quick response.

To answer your questions:

Usage duration:
The board has not been used for a long time. The debug console worked correctly only for a short period after I first received the board, and then stopped enumerating on the host PC. I cannot pinpoint the exact moment it failed.

Power supplies and other board functions:
Yes, I can confirm that the board otherwise appears to be functioning normally:
- The board powers up correctly via the USB-C port (no red LED indicating power-delivery negotiation failure)
- The boot sequence completes normally
- Other interfaces on the board are working as expected
- The only failure is the debug console UART (CP2105) — the micro-USB port no longer enumerates on any host PC

As mentioned in my original post, I also observed that the CP2105 area was running noticeably hot during the earlier (working) sessions, before the port stopped enumerating. This is what makes me suspect the CP2105 itself has been damaged rather than a host/driver/cable issue.

Additional information that may be relevant:
I have actually experienced this same failure on two separate PROC100A boards under similar usage conditions. Both boards exhibited the same symptom — the CP2105 became hot during use and eventually stopped enumerating on the host. The fact that two boards failed in the same way suggests this may not be an isolated defect.

Please let me know what additional information would be helpful, and I look forward to hearing back from your team.

Best regards

Hello User,

Thank you for the detailed inputs.

Let me check with the EVM team and update you.

Regards,

Sreenivasa

Hello User,

Can you please measure voltage at TP77 and TP76.

Regards,

Sreenivasa

Hello Sreenivasa,

Apologies for the delayed response due to the recent holidays.

Here are the voltage measurements for TP76 and TP77:

Hello User,

Thank you.

Let me check with the team and update.

Regards,

Sreenivasa

Hello Sreenivasa,

While we wait for the team's feedback, we are considering a potential quick fix to get our development back on track.

Since we strongly suspect the CP2105 chips are physically damaged based on the voltage measurements and the heating issue, we are thinking about purchasing new CP2105 ICs and performing the rework to replace them ourselves.

Before we proceed, I would like to ask your advice:

Is this a recommended approach? Would performing this rework void any potential RMA/replacement options if the root cause turns out to be something else?

We would like to repair them as quickly as possible, but we want to make sure we follow the right steps. I look forward to your guidance.

Hello User,

Thank you.

Let me check with the EVM team working out of dallas and update you.

Regards,

Sreenivasa

Hello User,

Please refer below inputs from the EVM team:

I think it’s okay to replace the CP2105 but before that Can we ask them to check the impedance on TP76 and TP77?

Regards,

Sreenivasa

Hello User,

Thank you.

As i check with the team can you please confirm you have the soldering/desoldering station setup that can be used in a controlled ESD environment to perform the rework?

Regards,

Sreenivasa

Hi Sreenivasa,

Thank you for checking. Yes, I can confirm that we have a fully equipped controlled ESD environment for the rework. Our setup includes ESD-safe soldering and desoldering stations, along with standard ESD protection gear (such as anti-static mat) to ensure the components are handled safely.

Best regards, Seungho Lee

Hello Seungho Lee

Good to hear about the setup.

I will check with the EVM team and update you.

Regards,

Sreenivasa

Hello Seungho Lee

Please refer below and confirm the measurements 

TP76 is the input of the LDO, if input is shorted then we won’t be able to see 4.9V on TP76. I am expecting output should show low because output voltage showing nearly 0V (0.26, 0.99) this relating that it is low impedance. One thing for sure, we can try replacing CP2105 on one of the board.

Please go ahead and change the CP2105 on one board.

Regards,

Sreenivasa

Hello Seungho Lee

Checking if you were able to make some progress.

Regards,

Sreenivasa

Hello Seungho Lee

Checking if you were able to make some progress.

Regards,

Sreenivasa

Hello Seungho Lee

Thank you.

Good to hear you have been able to recover the boards.

Assuming the rework was done few days back, can you please help confirm you have been able to use the board without any perfornce related issues.

Regards,

Sreenivasa

Yes, i have been using the boards for a few days now, and they are working perfectly without any performance issues or overheating. Thank you!

Hello Seungho Lee

Thank you for the inputs and good to hear the progress.

Quick question - in the initial query you attached another E2E - i assume this is for reference and does not relate to the issues you were seeing on the boards you had.

Regards,

Sreenivasa