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Connecting 2 boards with wires

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Bustigo

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hello,
i have this problem
i want to communicate two xilinx fpga of type sparton 3E with 5 signals (wires)
the two boards have the same clock .. the communication between them through 1 data wire and its enable and 2 other data wires and their enable
how to synchronize 2 clocks without addition of bits
thank you

---------- Post added at 10:54 ---------- Previous post was at 09:21 ----------

another question
i have to detect this output
01010101(000000....00)10101010101
when having stream of zeros more than 4 i want output to be zero but the stream is anded with clock :)
 

joelby

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If you don't want to do any additional synchronisation, transmit the clock from one FPGA to the other along with the data. If communication is bidirectional and high speed, you could generate a transmit clock at both ends.

If clocks are embedded, you could oversample the data at the receiver end if the signalling rate isn't too high. For higher speeds, you will need to perform clock recovery, special encoding, additional bits, etc.

I don't understand your additional question at all, sorry!
 

xtcx

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I dont understand why would you use,
1D+1E
2D+1E, since you said only enable for all data wires, instead you could use
4D+1E and send more data in same time and increase throughput, if at all it is your requirement.

> You said two clocks are same, does that mean they are coming from the same oscillator or how?. How do you say it is same clock while it is two physical boards?.
> If it is from same osciallator, then just add offset constraint to adjust the incoming signal phase and it is all done.

But instead....

Sending clocks is one way, but when it comes to high speed, it will cause too much skew. You have to either use some clock recovery mechanisms like Manchester endocing or 8b\10b encoding. I've done manchester encoding upto speeds of 20MHz between two Virtex -4 board for an optical fibre system. It worked perfect, with wire lenght < 1 feet. I'd recommend such mechanism to be used instead of wasting time in SSD or others until you really need that.
 

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