RAK4600 breakout board DFU mode

Hello everyone!
Ive been following the github guide on programming the RAK4600 breakout in arduino. The board documentation seems to be wrong with regard to the uart pins for AT commands (should be uart1, not uart2), and there is no mention on how to enter DFU mode.

I understand (based on the github guide) that “pin 10” must be grounded together with RST to enter DFU mode, but no matter which pin i try this on, it always boots up normally (AT interface prints initial messages over uart1). How can i enter DFU mode on the board? and which uart interface can be used for programming in arduino/platformio? Can i enter the mode via for example bluetooth?

Ive also tried programming it over st-link in platfromio, but i am not able to confirm that it is able to boot at all, so i ended up flashing the original firmware .hex again.

RAK4600 breakout board connected to PC via USB to UART, and also tried via st-link running on a flipper zero (crazy right?).



Welcome to RAK forum @WireFly ,

With regards to the guide of Arduino RAK4600, were you able to upload first the bootloader firmware via RAKDAP 1 or Jlink. If not, you wont be able to proceed to DFU mode.

I’d like to follow up on this too.

I’ve build a custom board based around the RAK4600 and would like to use the Arduino stack on it. I’ve flashed the feather_nrf52832_bootloader.hex bootloader using jlink/dap on the board successfully. I can confirm that the board has it running, because with the “nRF Connect” iOS app, I can discover an “AdaDFU” device and connect to it.

However, I can’t seem to upload code to it using UART DFU. I try to short nRST + P0.18/P0.19 (not sure which is the real one, I’ve seen multiple mentions), but my firmware upload just times out with the following message:

Upgrading target on COM3 with DFU package C:\Users\S�k�sd Attila\AppData\Local\Temp\arduino\sketches\55EEC7B9B2BAABF73E8F39117CEAD061\RAK4600_bleuart.ino.zip. Flow control is disabled, Single bank, Touch disabled
Opened serial port COM3
Starting DFU upgrade of type 4, SoftDevice size: 0, bootloader size: 0, application size: 96624
Sending DFU start packet
Timed out waiting for acknowledgement from device.
Sending DFU init packet

I’m a bit lost on what to try next, any help would be appreciated!