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Utterly insane idea here, but... this could be used to allow discovery
of network devices and unique addressing without having to have *any*
hardcoded unique ID number or address switch. Rather, the first device
in the ring after the master is number zero, the second is number one,
and so on. Each device, rather than just passing packets not destined
for itself unmodified, *subtracts one* from their address. Whenever a
device receives a packet destined to address zero, it knows it's for itself.

Reserve some special address for packets from slaves back to master,
which will not be modified (0xFF?).

Assuming every device responds to some kind of discovery packet with a
response saying what kind of device it is, you simply have to probe
address 0, then 1, then 2, and so on. All present devices will respond
with a response packet addressed to the master; once you hit the first
nonpresent address the master will get back its original probe packet
instead (with address zero, as it was decremented all the way around the
ring).

Chris

Tamas Rudnai wrote:
| Last time I have made something like this it is ended up as a token
ring :-)
| So the 1st PIC's TX goes to the 2nd RX, then it's TX to the 3rd RX and
so on
| (and the two end is to the host/master of course). The host sends a
message
| with an address, and if a PIC is not addressed then it just passes the
| message to the next PIC... Relatively easy to implement and it was fast
| enough to me.
|
| Regards,
| Tamas
|
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