After I have compiled a simple "Hello World" type of program into a hex file for the nRF52840. How do I upload it to the nRF52840 dongle over the USB connection from a PC running Windows?
I tried uploading using the nRF Connect Programmer, but that seemed not to work, and now it says "No devices available", whereas before it could at least find the nRF52840 dongle as a usb connected device. What to do now?
You are correct to use the nRF Connect Programmer app. Are you using the latest version of nRF Connect & Programmer (i.e. nRF Connect v2.5.0 , nRF Programmer v1.0.0-experimental.5). I would recommend following the getting started guide here. Have you put the dongle in bootloader mode by pressing the reset button on the dongle?
Yes, I've confirmed the version numbers: nRF Connect v2.5.0 , nRF Programmer v1.0.0-experimental.5 Those are what I used.
However, I did forget to put the dongle in bootloader mode by pressing the reset button on the dongle before uploading. Oops. Now ithe dongle seems to be bricked, because even though I press the reset button now, the nRF Connect v2.5.0 , nRF Programmer v1.0.0-experimental.5 can't even recognize the USB connection to the Dongle. It says "No devices available" This is all from within Windows 10 by the way.
Is there anything I can do to unbrick the dongle and bring it back to factory fresh condition? For instance, what is the factory hex file that's uploaded to it? Maybe if I try that, I can somehow bring it back to its original state.
I think I may see part of the problem: the dongle contains no dedicated USB chip. So, unless the "Hello World" sketch that I upload to the dongle contains some USB initialization code in it, the dongle basically loses all USB connectivity at that point. Correct? At least that might explain why nRF Connect can no longer find the dongle after I uploaded my Hello World sketch to it.
If that is true, what is some very simple USB initialization code that I can include with my "Hello World" sketch so that this doesn't happen in the future?
