Message handled framework

[jmnc2]

The protocol is message based and does not have an address but just broadcasts the message CAN network style. Maybe use the RTR and add some functions to help automatically reply when a unit that can handle the message receives it.

For example: If the unit at a light switch sends a message to say the light switch has turned on. Then the controller unit could reply saying message received. The sender then knows the message got through, and the controller was not too busy to get it.

If RTR is used, any new message would automatically have priority.

This would only be needed when the additional Ack bit that is acknowledged in the message frame is too complicated to do in an interrupt or in time, for example. If the controller could always handle message IDs that could be filtered with a bit mask, in the example, then this should not be needed.