This firmware is designed to work with the SIOControl PlugIn for OctoPrint. It could be used for general control from any device that can send commands over a serial line.
There are several versions listed. Each targeting a specific board. These boards can be obtained though my Tindie store front or in a number of other places. One of the goals of this project is to make it easy for people that dont have the ability to just build out a control board. This is why I have setup the Tindie store. If you have a board / MCU you perfer, you likley can just modify the Firmware and get moving. Knowing what MCU is on that board should give you a good starting point if you have another board with the same MCU.
If you are looking for some support, checkout the Firmware wiki and the PlugIn wiki. If you dont find what you are looking for there, I lurk a lot on the OctoPrint community site. Post there in the plugins section and I will likely see it and respond. You can also post an issue in the issues area here on GitHub.
Arduino IDE 1.8.19+
for Arduino.ESP32 Core 2.0.6+
for ESP32-based boards. .