Problem uploading firmware to RAK4631 using Arduino IDE

WisBlock
1

I’m trying to upload an Arduino_Led_Breathing.ino firmware to a RAK4631 on Arduino IDE and I get this error:

2025-04-20 22:20:23,771 Using board at serial port: /dev/ttyACM0
2025-04-20 22:20:23,772 Sending Application image.
2025-04-20 22:20:27,286 LIBUSB_ERROR_ACCESS: Unable to connect to trigger interface.
2025-04-20 22:20:27,286 Serial: Waiting 500 ms for device to enter bootloader 1/10 time
2025-04-20 22:20:27,791 Serial: Waiting 500 ms for device to enter bootloader 2/10 time
2025-04-20 22:20:28,296 Serial: Waiting 500 ms for device to enter bootloader 3/10 time
2025-04-20 22:20:28,801 Serial: Waiting 500 ms for device to enter bootloader 4/10 time
2025-04-20 22:20:29,305 Serial: Waiting 500 ms for device to enter bootloader 5/10 time
2025-04-20 22:20:29,810 Serial: Waiting 500 ms for device to enter bootloader 6/10 time
2025-04-20 22:20:30,315 Serial: Waiting 500 ms for device to enter bootloader 7/10 time
2025-04-20 22:20:30,819 Serial: Waiting 500 ms for device to enter bootloader 8/10 time
2025-04-20 22:20:31,324 Serial: Waiting 500 ms for device to enter bootloader 9/10 time
2025-04-20 22:20:31,828 Serial: Waiting 500 ms for device to enter bootloader 10/10 time
2025-04-20 22:20:32,334 Serial: Device is either not in bootloader mode, or using an unsupported bootloader.
2025-04-20 22:20:33,335 Serial: No ping response
2025-04-20 22:20:34,337 Serial: No ping response
2025-04-20 22:20:35,338 Serial: No ping response
2025-04-20 22:20:36,340 Serial: No ping response

Background:
I did some experimenting with the RAK4631 and uploaded custom firmware to it using J-Link which overwritten the original Bootloader it had.
After that I used J-Link to flash wiscore_rak4631_board_bootloader-0.4.3.hex to RAK4631 (got it from here: WisBlock/bootloader/RAK4630/Latest at master · RAKWireless/WisBlock · GitHub)
After that I try to flash using Arduino IDE and get the error I wrote.

PS: I also tried what seems to be an older bootloader from here: Releases · RAKWireless/WisBlock · GitHub (WisCore_RAK4631_Board_Bootloader.hex)

Did I flash the right Bootloader ?

2

There are two variants with different bootloaders available for the RAK4631.
(1) RAK4631 ==> Open Source community driven Arduino BSP for nRF52
(2) RAK4631-R ==> using RUI3, a BSP developed by RAKwireless with integrated LoRa drivers and LoRaWAN stack.

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Arduino_Led_Breathing.ini is an example for RUI3. and you need the RUI3 bootloader for it.

You can switch between RUI3 and Arduino Open Source BSP following our guides in the Documentation Center:

Updating RAK4631 to RUI3
Converting RAK4631-R to RAK4631

3

How do I install the RUI3 bootloader from scratch with J-Link ?
I dont have any of those versions flashed right now

4

If you want RUI3, you get the RAK4631_latest_final.hex file from our Download Center
RAK4631_latest_final.hex, make a chip erase with JLink and flash the hex file.