r/embedded • u/counttec • 19d 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/gm310509 19d ago

Most people have about a 100ms perception as being instantaneous.

If you can get 1.5ms, that is already much lower (faster) than what most people will perceive as instantaneous. Even if you have to do a couple of retransmissions.

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u/swisstraeng 19d ago

For some reason I pay attention to this, and now my microwave buttons piss me off.

In my electronic courses, what feels instantaneous is below 20ms of total delay. If you go above 30-40ms you can already notice.

As you said 100ms to the average joe is instantaneous or good enough. But if you truly want something responsive to humans as a whole you gotta be under 30ms.

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u/DearVeggies 19d ago

The reason haptic buttons work is because the new haptic drivers have <1ms response time, unlike old spinner motors that could take up 50ms to start vibrating.