sticky How the OCS works
Like OnStep the OCS an Arduino IDE based project, this one runs ONLY on the Arduino Mega2560. This simplifies development and enhances reliability which I rate as being of great importance to this project. To that end there is even industrial class Arduino Mega2560 hardware available if you want it. The Mega2560 also fits the role here as MCU performance is not a big concern and we want lots of I/O.
So basic hardware for an OCS consists of a Mega2560 and a W5100 Ethernet shield. Technically the OCS can run without its website, but that takes a lot of the coolness out of it! To see the charts of weather sensor data you'll need a little micro sd card (with the Charts.js file) plugged into the W5100 sd slot and to enable this optional feature.
To configure you decide which panels you want active to customize to your particular application, all panels except the "Status Panel" are optional. Most items within each panel are optional, you pick what is enabled and what isn't to customize to any situation.
For example if just getting started and all you have is the Sky Quality Meter you might turn everything else off:
If you buy a cheap 8 channel relay board from eBay you can use a jumper lead set to plug it right in then enable relay control in the OCS:
You can keep going on and on this way getting things working one step at a time so it doesn't become too much all at once. :)
The OCS panels are modular so new features can be added by following the same method. For example I will probably add an IP interface to OnStep so the OCS can park the mount and verify success before closing the roof. An option to take that task out of the hands of "less predictable" Windows/Linux machines is a good backup. Another panel I'm considering adding is a weather info. forwarding panel that sends up temperature humidity and barometric pressure to OnStep.
The OCS weather sensor support is modular (everything is in the Weather.ino file), if a library exists for a given sensor even an novice programmer can usually add support for it.
There are also ASCOM Safety and Roof/Dome drivers available for very low cost (sorry, not free!) I'll probably get around to adding the ASCOM switch driver at some point too.
More info. about the OCS is available on my site.