Debug Probe Not Found & J-Link Flashing Issues on TWR-KM35Z75M / KM34 MCU

[Mr7]

Hi everyone,

I’m using the TWR‑KM35Z75M board based on the KM35/KM34 MCU. I’m facing a major issue: the debug probe isn’t found in MCUXpresso IDE. Here are the symptoms:

1. "No debug probe detected" errors when trying to debug or flash via MCUXpresso.

2. After erasing the MCU flash using J‑Link, I can’t re‑flash or connect via MCUXpresso — the IDE no longer recognizes the board.

3. The orange LED D9 stays ON, indicating the board is in maintenance/bootloader mode but the IDE still can’t detect the probe.

4. I also changed the firmware on the OpenSDA chip—I flashed the J‑Link firmware, and it still doesn’t resolve the detection issue.

I’ve confirmed the OpenSDA chip is a M20AGV3N86B AFJRC with DAPLink bootloader v0243 / interface v0246, and it appears as an MSD drive when in maintenance mode. Yet the IDE still doesn’t connect.

[Mr7]

Hi @Celeste_Liu 

Thank you so much for your reply.

I had updated the OpenSDA chip firmware multiple times earlier, but the same issue kept occurring.

We also have a custom board that uses the KM35Z75M512 MCU (without an OpenSDA chip). It’s a completely virgin chip, and we use a J-Link device via the SWD header for flashing. The same issue is occurring on this board as well.

This issue seems to be very random in nature — sometimes it works, and other times the same setup fails without any clear pattern.

For reference, I’ve attached some pictures showing the problem.

[Celeste_Liu]

I noticed that the USB is not being recognized properly in your screenshot, which indicates that there is still an issue with OpenSDA.

[Mr7]

The notification you are referring to is related to the pen drive (USB drive), which was connected at that time, so that notification is for the USB drive. As I had mentioned earlier, the screenshots I shared were taken while I was working on a customized board that didn’t have any OpenSDA chip. I was flashing the MCU using a direct J-Link hardware connection via the SWD interface. Also, the MCU chip was virgin (i.e., being flashed for the first time), yet I was still getting the same error.

[Celeste_Liu]

Hello @Mr7 ,

I apologize for not noticing earlier. Screenshot 2 shows a custom board without OpenSDA. Now I understand.

I tried with the TWR board. When connecting J-Link directly to the KM35 SWD without using OpenSDA, I still couldn't reproduce your issue.

It should be noted that to connect an external debugger to the TWR-KM35, jumper J28 must be removed.

Here I attach my TWR board for your reference.

I suggest you refer to the TWR-KM35 schematic to check the schematic of your custom board, with a focus on the reset and SWD sections.

For the TWR board, could you please check whether the jumpers are correctly set? Additionally, would you mind verifying if the label on the back of your board says "REV A"?

BRs,

Celeste

[Celeste_Liu]

Hello @Mr7 ,

Thanks for your post. I did a test on my evb board, with no problem.

However, I noticed that the orange LED D2 stays ON instead of LED D9.

Please check my status under MSD, which should be mounted with the name TWR-KM35(D:), instead of showing "maintenance".

Please refer the DAPLink bootloader update | Mbed to check. 

When your device mount with the name "maintenance", you need install the DAPLink interface application, just open the device's root directory then drag-and-drop the firmware update into this directory. The firmware is attached.

Hope it can help you.

BRs,

Celeste

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