Updating SO2R Mini Firmware


The update procedure for the SO2R Mini is simple and painless. You will, however, have to download two files onto your computer to complete the process. As with the rest of our software, this process is designed for those on a Windows PC. However, with a little bit of Googling, this is easily achieved on any modern computer. As a side note, if you are technically inclined, and already have and use the Arduino IDE, and would rather use that, you may update the firmware using the uncompiled Arduino sketch, which can be found here.

Prerequisite Downloads:

SO2R Mini Arduino Firmware Compiled (Hex)

XLoader Firmware Writer


  1. Download both of the above links, and extract them from their respective zip files. Each will extract to a folder.
  2. Open your newly created folder labeled “XLoader”
  3. Inside of said folder, double click on “XLoader”, which should appear as a “.exe” with a small icon adjacent to its name.
  4. The program should launch and should appear similar to the screenshot pictured below.
XLoader Launched and Unconfigured

5. Click the “…” button to the right of the “Hex file” bar, and browse to your previously downloaded .hex file.

6. Click on the “Device” dropdown, and select “Duemilanove/Nano(ATmega328).”

The author’s view of XLoader with the all needed fields filled in. Leave “Baud rate” untouched. Know that the Hex file path may be different for you.

7. In the COM port drop-down, select the COM port to which your SO2R Mini is connected. If unknown, launch Device Manager, and find the COM port that correlates to a device labeled with CH340 or similar as described in the Cabling and Installation Guide.

8. Press upload, and wait for the status at the bottom of XLoader to indicate a successful update! We have had reports that some users with Arduino-Clones have found that they needed to set the baud rate to 115200 for programming. If you run into an error, give that a try.

9. Success! If you encounter any issues, feel free to email us, and marty@so2r.org.