Hi there,
I have a project where one master PIC needs to communicate with many (5-10pcs) slave PICs. The master PIC will be placed around 1 meter from the first slave PIC and the slave PICs will be spaced with 1 meter each in a straight line.
I need ready made cables and connectors and found 1 meter RJ-45 network cable to be pretty cheap along with plastic RJ-45 connectors.
What would be a good choice for communication?
My thoughts are:
1. Could I connect the slave PICs to the cable and just "sniff" the data (is that what they call multidrop bus?) or should I use daisy chaining? Would I need some kind of termination if not using daisy chaining?
2. Could I connect the PIC USARTs directly through the cable or should I use tranceivers (RS-232 or RS-485) even on these short distances?
Speed requirements: The master needs to poll all the slaves in turn and should be able to poll 10 slaves in 10ms. Polling is just asking for data (maybe just a 1 byte address) and the slaves would respond with 4 bytes data.
Reliability and pricing is important, I guess reliability could be secured using checksum for the data and cheap transceivers or even no transceivers would keep price down.
The PIC device has not been selected yet, so I'm open for suggestions.
I have been using RS-232 and RS-485 before and knows how the hardware works, but I'm open for other options as well.
Edit: The slave PICs are connected to some other device that needs 3V supply, so 3V supply would be ideal. Also the cables needs to supply the power but I guess that's not a problem with 8-wire CAT5 cables, but I don't know how the supply should be connected in the cable because of the twisted pairs.