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@Moon what kind of sensor or transductor is that? What are you measuring when press your ring into it?

@saiferion The sensor is called an iButton probe. it makes contact with a data+power line and a ground, and communicates using a protocol called 1Wire.

When I touch the ring, the probe provides power to the ring which contains a microprocessor that communicates over 1Wire. the bus master side (arduino) does a search command over the network and the ring replies back with a family id (what model of iButton) and a 48-bit unique ID, and a CRC to check that they're intact.

When I get the response, I parse the ID and compare it to the ID I have stored as belonging only to my key, and then play a tone and led pattern depending on if it matches or not.

@Moon wow i never heard of those! That is a neat idea tho. The button feeds and and connects the processor in the ring to the 1 wire pin of the arduino .. right?

I really need to undust mine. I was using it with a sim800l module to process sms as commands for a gate but i stopped at some point

@saiferion yeah. believe it or not, this system has been around since the late 1990s. That ring on the video is actually 22 years old. It has a java processor on it but the battery is dead so only the identification part works when power is supplied.
@Moon @saiferion seems like a colossal waste of resources and energy to make a non-rechargeable computer.
also: ibuttons are still in use! my old apartment used them for electronic door locks to prevent key sharing or duplication (although i'm sure there's a way to spoof it)
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