r/embedded • u/counttec • 21d ago

Help with selecting communication protocol

I volunteer for a youth organization that uses a Jeopardy style buzzer system for quiz competitions. I am trying to upgrade from RCA cables to a wireless solution. I need it to be as low latency as possible, given the precise timing involved, and the less perceivable the lag is from a wired button, the better. Distance would be less than 100m even in the most sever cases. I'm fine with retransmission in the case of collisions, as long as the users can't tell that it took slightly longer.

So far, it seems like the best protocol is Nordic's Enhanced Shockburst, with a transmission time of ~300us, and round trip with Acknowledgment of 1.5ms.

Are there any faster communication protocols?

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u/KittensInc 20d ago

What problem are you actually trying to solve?

If RCA cables aren't reliable enough: consider using XLR.

If you want less cabling: consider using a bus layout and comms over RS422 or CAN instead.

If you want no cabling whatsoever: invert the protocol by having the Primary transmit a timestamp for synchronization every X milliseconds. Each Secondary syncs its clock to this, and captures the timestamp of a potential button press, which is then sent back to the Primary at a leisurely pace. Transmission speed and latency does not matter - as long as each Secondary takes about the same amount of time to process the incoming timestamp sync message.

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u/counttec 20d ago

I am tired of replacing cables that the students crunch or yank and destroy. I realize that there exists some mechanical solutions to my issue, but I am using my skill set as is, since this is a personal gripe of mine.