Hacky sack kick counter with remote digital display counter

I would like to have a remote counter that counts how many times in a row I have kicked a hacky sack.

For example, a small accelerometer that sends a pulse over AM/FM when kicked, that is picked up and rendered on an alarm clock-like display. The display should have a reset button on it for the counter.

The “bean” aka accelerometer or whatever gadget that I put inside the hacky sack should be as small as realistically possible.

I supposed that is probably still too large? It’s the smallest integrated package I know of with rechargeable battery and accelerometer in one package. It has bluetooth and wifi and could send message to your phone.

The MPU I used in Time Turner: Time Tracking Tool in a dodecahedron they haven’t released information on how to use the interrupt function, which would be exactly what you would want in this application.

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Now I have to get one to play with! I know Don needs one too!

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I DO NOT NEED THESE!, I DO NOT NEED THESE!,I DO NOT NEED THESE!,I DO NOT NEED THESE!..

https://docs.m5stack.com/#/
https://docs.m5stack.com/#/en/uiflow/uiflow_home_page

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There are motion-sensing switches that are basically a weighted wire spring inside a loop of wire that is the other contact that are designed to connect when moved. I don’t know what they are called to link to a part, though. It would be possible to use such a sensor instead of an MPU but it could miss hits that are aligned with the axis of the sensor wire.

I think most accelerometers have “fall detection” built in.

Yeah, I just discovered sadly that the one I used recently, the MPU-6050 that I thought was open-source-friendly, lets you use half the features (basically all the ULP features) if you get their proprietary API and tools. That really messed up my project.

@mcdanlj @HalfNormal @donkjr I have found a finished prototype hacky sack called the Iguana Smart Sack: https://www.iguanasmartsack.com/specs

However, there are issues with it. Firstly, why does it need a battery? When you kick it, it could ‘chirp’. Secondly, why does it need to be as large as a large watch battery? That way you can simply insert it inside any hacky sack. Their hacky sack does not look ergonomic to me, I prefer my own. What about some sort of ‘piezoelectric chirper’ that can be picked up by ie smartphone audio, but is possibly even not detectable by humans?

If I were trying to design one to do energy harvesting I’d more likely use 433Mhz than audio. Using the battery seems easier to me. I’d expect ultrasonic signal to be muffled by beads in a sack. YMMV.

You are right. When I kick a hacky sack the sound it makes is due to the inverse piezoelectric effect. I should just develop a smartphone app that works on audio, without anymore electronics than the beans inside the hacky sack.

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