I am half-way through building my home automation system. As an electronic engineer/software developer a lot of this has been rolled myself from scratch and I will hopefully be starting to blog more and build up/publish my story and workings once complete.
I am now at the point of lighting automation. I have approximately 30 wall switches running a prototype touch sensor faceplate and I need to now connect these back to my Win7 Embedded automation computer. I also need to connect about 30-40 dimmers and relays.
As far as I can see I have a couple of options for protocols both at physical/application level and really am looking for any comments or advice on the below options, plus if anyone has any other suggestions.
Right now, all controllers are running off ARM M3 processors and I have both Ethernet and CANopen stacks available. The system needs to be "multi master" and ideally support both event driven (e.g. someone presses a button) and process driven (querying a sensor every 30 seconds, or asking a specific node a question).
- Multi-master and automatic error correction/collision avoidance
- Process, service and event options for messages
- Can be complicated to "virtually wire" up device. Lots of configuration potentially required
- Cheap to implement in hardware, relatively scalable. Limit of 127 devices on a bus. Daisy-chain network.
- Multicast UDP, or broadcast? Not sure which is more appropriate
- Probably have to roll my own messaging protocol or API on-top to handle all the types of events I require, not sure about event driven actions
- Star network, BUT could support PoE which is nice
- More expensive in hardware
- Much more expandable in software (potentially infinite number of devices, etc).
Has anyone got any comments or thoughts on which may be the best route to proceed? I have a feeling Ethernet may be the way but worry there is far more implementation required in software.