Upload RUI firmware to breakout board

Issue: RAK4200 breakout switched to boot mode but firmware upload tool stuck on Boot message

Setup: RAK4200 breakout, USB to serial, dupont cables


I’ve created a small app to use an I2C sensor on RUI but I’m experiencing issues getting it on to a breakout board and now have TWO stuck saying <BOOT MODE> when I put them on the serial tool but it won’t proceed with the download using the firmware tool. I’ve found that it only really works if I provide the board with independent power. I have to cycle the power on the board for the firmware tool to see that the board is in boot loader mode, which it acknowledges on screen, and then just sits there for 15+ minutes before I get bored and try something else.

Firmware is reported to be
Boot loader says it is 3.2.6

I have successfully uploaded this firmware to a RAK4200 EVB and I’m getting the debug output I’d expect to see from my code.

Ideally I’d like instructions on the settings for using a proper programmer (like an ST-LINK v2 or SEGGER) so I don’t have to mess about with two serial based tools plus independent power plus, judging by the firmware update tool on the EVB, a quite slow download speed.

And how do I take the breakout boards out of Boot Mode - or do I have to reflash the boot loader - which on the EVB previously didn’t end well.

Hoping to catch @Nicholas or any one else that knows these things so I can finish this work today in my time zone!

Dear Nick,

What tool do you use to re-burn when you enter Boot mode?

The firmware tool that is on the website - as mentioned in the post above - it’s the one on your website and it works for the 4200 on the EVB.

I discovered the AT+RUN command to get the two stuck in boot mode out again, but they still don’t allow me to down load any firmware - the one I produced using the RUI compiler or the default downloaded from the website.

If I can get this working TODAY using a different tool, I’d appreciate instructions - you have my email address from previously.

So, after a few wasted hours, and yes, I am more than slightly annoyed, which if you translated that from Englishman to any other nationality, is really p155ed off, it’s working.

The RUI compiler produces files that can only be downloaded on to a device with boot loader 3.2.3.

This needs adding to the compiler website so it doesn’t trip up anyone else in the near future.

And RAK needs to have an announcement channel so when/if you update the online compiler &/or the boot loader download, we get told about it clearly so we don’t end up spinning our wheels like this again.


I’m sorry, We didn’t make it clear.

This will be something we need to fix. Thank you for the lead.

Best regards!

1 Like

This topic was automatically closed 2 days after the last reply. New replies are no longer allowed.