Unable to use Debug out on nRF 52840 dev kit to program nrF 52840 usb dongle

RE: Unable to use Debug out on nRF 52840 dev kit to program nrF 52840 usb dongle

haakonsh — Mon, 23 Sep 2019 14:50:04 GMT

I think you need to include the bootloader in the application you want to debug, see https://devzone.nordicsemi.com/nordic/short-range-guides/b/getting-started/posts/nrf52840-dongle-programming-tutorial?CommentId=89e0af9b-7279-4548-9d9c-8ef7d60699fb for details.

RE: Unable to use Debug out on nRF 52840 dev kit to program nrF 52840 usb dongle

Ank — Thu, 19 Sep 2019 22:41:53 GMT

Update: If I erase the whole chip with the J-Link (thus removing the Nordic bootloader), & then program my firmware through the Jlink, it works. My firmware has the proper setting for REGOUT 0 done already.
What is the missing step that I am not doing, if I want to keep the Nordic bootloader AND program my application firmware to the USB dongle? If I program the same through nRF Connect on the same USB dongle, it works!

RE: Unable to use Debug out on nRF 52840 dev kit to program nrF 52840 usb dongle

haakonsh — Thu, 19 Sep 2019 13:11:20 GMT

If you've run an erase all j-link command then the output voltage settings for REG0 will be 1.8V instead of 3.0V. This means that the OB J-link debugger can't interfaces with the dongle as it's I/O voltage level is ~2.8V.

If that's the case then I suggest you disconnect the dongle from the USB supply and provide 3.0V power to the 'VDD nRF' test pad on the bottom side. This will then allow you to interface the debugger with the dongle.

If you need to interface with the OB J-link and use the USB at the same time, in the event that REG0's output is 1.8V, then you need to cut a solder bridge who's located right next to the 10-pin connector on the bottom side. This will disconnect the 5V USB rail from VDDH, preventing REG0 to output anything on the VDD nRF supply.