ST Nucleo WB55RG - Can't enter DFU anymore

[Quentin Morlet]

Hello,

After playing around with the Nucleo board and wanting to try the simple BLE Beacon example, I believe I somehow got the bootloader stuck.

I could enter DFU mode the first time and flash accordingly to the instruction given. However, trying to flash another binary gave the STCubeProgrammer a segfault, and now the device is not recognised anymore and can't seem to be flashed through USB.

Is there any way to recover? Possible to rewrite bootloader / FUS through the STLink?

Thanks a lot

[Quentin Morlet]

So, end word is that there absolutely no way to revert this state? No mass erase or factory reset for the chip is available, by JTAG or anything else?

[NJian.1]

Hey man,

i have the same issue with you, and i already fixed this problem, i'm come here to solve your problem.

if you want to into DFU mode that you need change the nBOOT0 = 0 in option bytes and apply program in MCU as below picture

, and when you run the application code that you needs change the nBOOT0 back to 1, hope this has solved your problem!

[Remi QUINTIN]

Indeed you have to check the option bytes when you move from the SWD port to the USB port and vice versa.

But this is of no use if the SFSA option byte = 0.

Note a very important point: If you are using CubeWB FW package V1.5.0 and update the FUS to the new version 1.1.0, then you will be able to revert to the manufactory configuration (even with SFSA = 0)  if you perform the sequence below:

• Write 0x00008000 at @0x5800040c
• Set RDP level1 then Level0

This will prevent having a blocked board forever. After this sequence, the board is blank with only the last FUS V1.1.0 and the SFSA back to the value 0xF4.