MIMXRT1060-EVKB is loosing external debugger connection after flashing a faulty image

[sergeylyubka]

We are using MIMXRT1060-EVKB with an external debugger.

This is done to automate lab testing : CI builds flash new firmware and test is through the external debugger.

However, sometimes the firmware that is built, is broken. This breaks the SWD connection.
We need to manually update the DIP switch settings on the EVK to enter the bootloader, then we flash the "golden" image, then change DIP switch again, then reboot the EVK.

All in all, this is unacceptable, as our tests should be fully automated.
Honestly, I find it very surprising, and very wrong, that the firmware on flash can kill the SWD access.

QUESTION: can the external SWD connection be recovered without DIP switch dancing, after flashing a faulty firmware?

[sergeylyubka]

Thank you @kerryzhou . The recovery document you provided tells nothing new, as I already mentioned in my original post that we know that we need to recover using boot mode switch. 

My question was about - how to deal with the SWD loss without that. You say that is a "feature" of RT, I would rather call it something else - an appalling design failure.

However you mention "until now". Could you elaborate on that please? Is there a potential to restore an SWD connection using SWD, without dealing with boot mode and flashing the "right" firmware? Any pointers to investigate further?

Thanks for your attention.

[kerryzhou · Accepted solution]

Hi @sergeylyubka ,

  So sorry for my later reply because of China Spring Festival.

  Another way, do you have the JLINK or not?

  You can use the JLINK commander to erase the FCB+IVT area.

  Just like this:

After the erase finished, you can use the CMSIS DAP debug it in the IDE again.

I have tried it, didn't switch the boot mode, still in the internal boot mode.

If you are using the MIMXRT1060-EVK, you need to isolate the on board CMSIS DAP when you use the external JLINK, you can disconnect the J41-J50.

Then connect your external JLINK to the J21 JTAG interface.

Please try it on your side.

If you still have issues about it, please kindly let me know.

Best Regards,

Kerry

[sergeylyubka]

@kerryzhou Thank you. I appreciate the effort, time and attention you put into that.

[kerryzhou]

Hi @sergeylyubka ,

  You are always welcome!

  Any new issues in the future, welcome to create the new question post or the case, we would like to discuss with you together!

Best Regards,

Kerry

[sergeylyubka]

Hi @kerryzhou ,

Thank you!

Appreciate your attention.

Yes we do have a J-Link, but the external debugger we use for the automated tests is not a J-Link - however that is not critical.

You provide an example that erases the initial area of flash using a J-Link command. It works by talking to the Flash controller over SWD, so it assumes a working SWD channel.

Can you confirm that you're executing that J-Link command against a device that is broken? Based on the screenshot, you're using a device that is perfectly healthy, and just erasing flash on it. Our experience, as stated in the original message, that SWD does NOT WORK on a broken device, so your example does not really apply.

Please clarify!

[kerryzhou]

Hi @sergeylyubka ,

  Don't worry, in fact, when I meet the issues, I also meet the SWD connect issues.

You can see, the IDE mass erase also can't work when I still in the internal boot mode:

Then use the JLINK, it can do the erase:

Maybe you also can find one JLINK to do it.

Another way, in your MIMXRT1060-EVKB, you can firmware the on board debugger to JLINK.

You can use the LPCScrypt to update it:

https://www.nxp.com/lpcscrypt

Please note, you also need to update the JLINK firware:

https://www.segger.com/products/debug-probes/j-link/models/other-j-links/lpc-link-2/

Please try it on your side.

My test result is from the external Segger JLINK Plus, and disconnect the on board CMSIS DAP.

You can try to firmware the on board debugger directly from CMSIS DAP to the JLINK.

JLINK commander can be found from the Segger JLINK driver after you install it:

https://www.segger.com/downloads/jlink/

If you still have question, just kindly let me know.

Best Regards,

Kerry

[kerryzhou]

Hi @sergeylyubka ,

  When you download the invalid code, normally you need to enter the serial download mode, and do the external memory mass erase.

The detail information, you can refer to my document:

https://community.nxp.com/t5/i-MX-RT-Knowledge-Base/RT-board-recovery-for-debugger-connect-issues/ta...

Until now, it is the RT feature, still need to change the boot mode to the serial download mode.

Wish it helps you!

Best Regards,

Kerry