PicDude wrote:
> So far, my thoughts for most of this are as follows...
> - Master will query each node in sequence asking "do you want to send
> anything"?
> - Master will wait for a specified time for a response.  No response in
> specified time means an error occurred.  I've been toying with the idea
> of re-trying once or twice, but haven't determined that yet.  Any error
> is indicated at the master station (specifics TBD).
> - When the master gets a response, it will be addressed on the bus to
> the master, but the data will indicate if it is intended for another
> station, and the master will pass it along.
> - I'm planning to implement an acknowledgement to the slave that
> message was received.
> - Master will send out message on the bus, which the appropriate slave
> will respond to.
> - Master will expect an acknowledgement within a certain time, else
> error.
> - Master will continue with next node.
> - I might need a broadcast message, but will not expect an
> acknowledgement for that.  If I do, I'll have the master send it to all
> stations individually/sequentially.  Latency is not an issue here.
>
> At this point, there will be about 10 stations, but I was planning to
> allow for 16.  However, for simplicity, and since traffic will be
> relatively low, I'm thinking I'll just send a full byte as the station
> id/address, and another with the command, and perhaps a third with some
> checksum, etc.  That last part is yet TBD.
>
> The messaging will be very specific to each station, so new nodes will
> require a firmware change at the master, since it will need to be setup
> based on the type of node.  I don't plan to put anything automatic in
> for this.

A lot more complicated than you first thought, isn't it?  And there are a
few more details you haven't yet thought about.  Yes, I've done this.

Now, is this *really* simpler than CAN?


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