What specifically are you interested in? I’ve spent quite some time reverse engineering the source code of SiK radio to understand how it works when writing my GUI config utility. In a nutshell:
- SiK radio is not a transparent serial link - it requires MavLink1 or MavLink2 framed data.
- SiK radio operates in simplex / half-duplex mode
- SiK radio is configured using AT command set. A remote radio (when connected) can also be configured.
- SiK firmware exchanges extra signaling data in addition to user data to maintain lock on frequency hopping and inform participant on signal levels.
- SiK supports flow control on both serial and air interfaces.
- SiK TDM code is very much self-documenting (if you have some background knowledge).