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Please be positive and constructive with your questions and comments.


by stewkingjr on Fri Jan 21, 2022 3:59 pm

My students would like to build timers. Picture a setup with two devices that are interconnected wirelessly (because wired is easy enough but not flexible enough). One device detects the start of an event by some external signal and notifies the other device which is the one that really keeps the time. This other device sees its own input signal to stop the timer. Students have had experience with micro:bit devices so most of this task should be ok. The only unknown is the wireless part. I'd like to expand their knowledge to include feathers and the like and i was hoping that i could do that. I envision the wireless part being BLE, but it's not a show-stopper. And these are 9th grade students so setup should not be a tremendously tedious task.

My real question is which device(s) should i use to be the starter and which device can i use to be the timer/display/stopper? There are so many choices to go wrong on. Also, can i do this cheaply enough (less than $100US per pair)?

Thanks in advance,
p.s. To keep multiple sets from confusing each other, we could use a dip switch to set matching 'addresses.'

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Re: Timers

by kevinjwalters on Tue Jan 25, 2022 9:28 pm

What language do you intend to use?

I did some timing, synchronisation and BLE communication in Circuit Playground Bluefruit Quick Draw Duo. That code should also run with minor modification on the CLUE. A gizmo display can be bolted onto a CPB if you can tolerate the loss of most of the pads for IO. BLE competes in an often busy radio spectrum which means you'll need to work out if those (variable) delays are significant for your application.

CLUE Rock, Paper, Scissors Game using Bluetooth also uses BLE but it's using advertisements as an unreliable broadcast which involves more work by programmer and shouldn't be used if you only have pairs of devices that need to communicate.

I think the best value device would be the micro:bit V2 but I don't know if BLE has been made to work and tested on that.

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Please be positive and constructive with your questions and comments.