Can't update bootloader/enter DFU on rak4631

WisBlock
1

I have a rak4631 on a 19007 board that I can’t enter DFU on. I was trying to flash meshcore and ran into issues so I updated the bootloader and now it’s stuck.

I think I accidentally flashed it with 4631-r instead of the regular 4631 one. Double tapping the reset button no longer puts it in DFU mode, and using web flashers “Enter DFU mode” buttons gives errors now. Connecting to it via minicom or tera term won’t let me send AT+BOOT and does nothing, and all the commands to send firmware/bootloader to the device found in the docs fail with a device timeout. This happens on archlinux and windows 11.

The only other solution I’ve found is grounding UART2_TX but I can’t find any info on where that pin is. I don’t have access to a DAPlink or any other debug/flash tool. Attempting this all over USB, bluetooth is unresponsive.

What do I do?

2

Welcome to RAK forum @jonwade92 ,

If double-click reset doesn’t proceed on DFU mode, your bootloader has problem (assuming USB cable, PC and drivers are all ok).

If you accidentally upload RAK4631-R (RUI3 FW), you should have at least have COM port detected then a reply to AT+VER=? If either of these two is not working in your RAK4631-R update attempt then something got wrong along the way.

The only way you have to recover it is via DAPlink (RAKDAP1) or Jlink (which is more reliable approach).

3

No commands from minicom work at all including AT+VER=?. Com port is detected on windows, ttyACM0 on linux, but any attempt to send anything to the device fails. Sounds like I’ll have to order a DAPlink.