I don't really know much about writing protocols or implementing them,
but I had the following idea. I don't really know if it's the "right"
way to go about it, so please comment on it.

I'm trying to design a multi master protocol for RS485 networks
(specifically working on how the microcontroller will handle the data
at this point).

The MCU will have an ISR as follows, which will be called every time a
byte is received:

ISR() {
    if buffer not full
        push byte into a FIFO buffer
    start(processing_thread)
}

processing_thread() {
    if frame complete (if we have a full, complete frame in the buffer)
        process_frame() (process the frame, handle the message, whatever)
    stop(processing_thread)
}

Pastebin link for those who have trouble reading the above formatted
text: http://pastebin.com/Z8YRt69k


In this way, the ISR stays relatively free most of the time. It only
executes some short code when a byte is received. So, even if the
processing of the message data takes a long time (for whatever
reason), the ISR is free to continue pushing data into the buffer.
Meanwhile, the processing thread runs "in the background" to handle
the received data.

I would imagine that using an interrupt (rather than consistently
polling for data) is far more efficient. Is this the way it's usually
done in the microcontroller world? Or have I totally missed something?
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