nRF52811 on u-blox BMD-360 module: Failed to load readback protection status: async task failure for id: 4040685450 msg: JLINKARM_DLL_ERROR

[JuanHG]

Hello,

Our project is based on the "ble_app_template" example with added BLE custom profile.

We have been developing our software on the u-blox "BMD-300 evaluation board 320-00050" without any major issue on the debugging/programming side. We have now our PCB manufactured with some brand new BMD-360 modules soldered on them and now we have some readback protection issues with the exact same code that didn't show any problem on the u-blox EVK, which is supposed to have the exact same module.

The u-blox EVK has its own programmer/debugger which doesn't have an easy debugger output so I use the J-Link debugger from the nRF52840-DK (PCA10056 2.0.1 2020.43 683503066) I have. Connection is done through the P20 connector (the 0.1in/2.54mm one) with VTG connected to VDD_nRF and GND connected to GND_DETECT.

The is what I was able to do so far:

• Program the S112 softdevice with nRF Programmer v2.3.3 utility
• Read the flash to make sure the softdevice has been programmed correctly
• Program the application code with Keil µVision

Now the chip is supposed to run but it doesn't: BLE is not advertising and UART debug is not printing anything. Please note that I flashed the exact same .hex file without recompiling on the u-blox EVK and the code is running just fine.

This is what I can do then:

• To have the debugger working and recognizing the MCU I often need to disconnected and re-connect the USB cable several times. Sometimes to get it to work I must connect the nRF52840-DK debugger and then connect the target nRF52811 TAG-CONNECT cable to have it recognized by Keil
• Launch "nrfjprog --recover" to erase the uicr register but this also erases the flash code, leaving me with a chip I must re-program
• Keil sometimes prompts me that the chip is secured and I need to un-secure it to proceed. If I answer YES, it erases the whole flash as wel as the UICR

Would it be possible that I have a different hardware version of the nRF52811, other than the one that is on the u-blox EVK ?

What could I do to sort this issue out ?

Even if this readback protection is enabled, why would that prevent the application programmed on the MCU from starting correctly ?

Thanks in advance for your help.

Best regards

[JONATHAN LL]

Program the S112 softdevice with nRF Programmer v2.3.3 utility

This version of the programmer is a bit old, try to update to a newer version of the Programmer app, latest is v3.0.2

I flashed the exact same .hex file without recompiling on the u-blox EVK and the code is running just fine.

Could this be a HW issue?

Even if this readback protection is enabled, why would that prevent the application programmed on the MCU from starting correctly ?

readback protection should not prevent the program from running. 

Regards,
Jonathan

[JuanHG]

Hello Jonathan,

Thanks a lot for answering my question !

Could a PCB implementation problem be the cause of this readback error ?

Thanks in advance

Best regards

[JONATHAN LL]

JuanHG said:

Could a PCB implementation problem be the cause of this readback error ?

Do you have any other issues with other applications, have you tested different examples? 

If the issue is not reproducible in other applications, so if you test with a different example then there are no issues, that would indicate that the issue is with the custom application. 

issues that could be HW related is poor connection on some of the pins, if the soldering is bad, then lots of strange errors could occur. 

Regards,
Jonathan

[JuanHG]

Hello Jonathan,

Finally it was a code-related issue, somehow the pinout was wrong and now it is working just fine from the debugging point of view.

Sorry for the waste of time and thanks a lot for your support !

Best regards

[JONATHAN LL]

Thanks for updating :D