NRF52840 dongle is not working after selecting recover option in NRFgo studio

[Saagar]

HI 

I am programming NRF52840 dongle using nrf52840 dk 

i have flashed blinky code to my nrf52840 dongle it programmed sucessfully after that i have erased the dongle by selecting recover option in nrfgo studio from then my dongle is stopped working.

Thanks and Regards

[Einar Thorsrud]

Hi,

nRFgo Studio is not compatible with the nRF52840 dongle. However, it should be able to cause any problems either, since nRFgo Studio needs a debugger. Can you double-check that you are using a nRF52840 dongle and not a nRF51 dongle? Or that you are using nRFgo Studio and not nRF Connect for Dekstop?

If you are using a nRF52840 dongle, then please try to program it again from nRF Connect for Desktop Programmer. You may need to press the sideways reset button to get it into USB DFU mode, which is required in order to be able to program it. You will then see a red pulsating LED indicating that it is in DFU mode.

[Saagar]

HI 

I am using nrf52840 dk to program nrf52840 dongle and  i have programmed the blinky application and it was running sucessfully and after that to erase the board i have selected recover option in nrfgo studio and after that it stopped working

[Einar Thorsrud]

Ah, I see. I read your question too quickly. Then the problem is clear. You have erased the entier flash of the nRF52840 dongle, including the UICR, which holds the configuration for regulator 0. The default configuration (which is now used) is 1.8 V, and that is too low to be programmed from the nRF52840 DK. To recover you either need to use a debugger with a level shifter, or do some HW modifications to the dongle. This is described in the past part of the nRF52840 Dongle Programming Tutorial.

[Saagar]

 I have refered nRF Connect for Desktop Programmer and while flashing the bootloader its shows error as --IDcode not found check target interface ..i am using nrf commandline tool for flashing bootloader. 
 Can you please explain in detail procedure

Thanks and regards

[Einar Thorsrud]

Hi,

As mentioned, it seems you have erased the UICR of the chip (as part of the full chip erase). Therefore, the board chip has a too low VDD voltage to be debugged from a DK. The procedure is described in detail in the last part of the nRF52840 Dongle Programming Tutorial.

You have two options. Either use a professional debugger with a level shifter or modify the dongle HW to use a higher supply voltage. If the first is out of the question, then you need to:

1. modify the dongle as explained in detail under External regulated source.
2. Power the dongle from an external regulator that is about 3 V
3. Now program the device via a debugger (for instance the DK can be used now). Make sure that the hew firmware properly configures REG0. (see nRF52840 Dongle Programming Tutorial for details).