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Attempting to create tiny, wearable, covert, simple button click counter for behavioral mod Answered

Hi all,

I've been searching both this forum and the internet in general and strangely have not come across what I'm looking to do even
though to me it seems very simple.

Here are the specifications/requirements of the device that I am trying to create:

-extremely tiny form factor (ideally a ring sized device but I'll settle for a thin bracelet)
-unobtrusive/inconspicuous (I guess a thin bracelet that could hide under a sleeve might be best)
-battery powered/untethered (This is essential. The device would be useless if depended on a connection to a computer or wall socket)
-battery life must last a full day
-data logged is just a simple time/day stamp that would indicate when a button was clicked by the wearer
     (wearer would manually click the button during the day when certain thoughts came up for him/her)
      This requirement indicates that the micro controller chosen would need a clock built in and
       some kind of storage
- be able to upload the data to a computer

I did my preliminary research considering these requirements and I came up with the following electronic components that might

- teensy 3 (has real time clock and 2K EEPROM which should be plenty of memory for storing date stamps)
- ulog (1MB of usable space across 3 analog channels, couldn't find anything about a built in clock)
- Pro Micro - 3.3V/8MHz (not sure about built in real clock  but storage is 32K flash space)
- OpenLog (wasn't clear about how much built in storage and didn't see any build in real time clock)

These are the best I could find. If anyone has better suggestions please let me know?

My idea is to connect a Mini Push Button Switch to one of the digital inputs on one these micro controllers/data loggers
and write a simple sketch that records the time the button was pushed in a MMDDYYhhmm format (10 bytes per click).
To power any of these micro controllers/data loggers I was planning to use a Coin Cell Battery - 12mm.
I was going to sew the micro controllers/data loggers on one side of a thin piece of material that would serve as a bracelet and
sew the battery on the other side. Although I'm not sure how to fix the battery to the cloth and how to connect it to the
micro controllers/data loggers. I'm guessing I could find some kind of battery holder for the 12mm cell battery?

Other Questions about my assumptions:

Will I have enough storage left over on the flash space or EEPROM to store
the data click after the sketch code has been loaded in?

Will a watch battery provide enough energy to run this device all day?

Is the Coin Cell Battery - 12mm the correct external power source for this project?

I encourage any feed back, criticism, comments, help of any kind to move me along with this preparation
so that I can move forward and purchase the parts I need.





7 years ago

~Have you thought about using pre-built hardware like a smart watch?

The Chronos from Texas Instruments might be suitable. Or something similar, there are many available. Look for one that allows you to map functions to buttons. Without reading through all the documentation I can't be sure the Chronos will do this, I'll leave that up to you, but it's a direction to look in that you might not have tried.



Reply 7 years ago

Or this:


7 years ago

For one the data wouldn't be able to be stored on the EEPROM. Temporary variables can be stored there but you wouldn't be able to plug the micro controller back into the PC and retrieve those values. It would have to go to an SD card or some other storage medium if you want to access the data. So you will need additional hardware to send the data out over serial to an SD/micro SD card reader/writer.

You will need a 5V power source to run things and the smaller the battery is the less time it will run. Most 12mm coin cell batteries only offer 3V so you'll need 2 of them to power the controller. You may find you'll need to use AA batteries to get more that a few hours of run time. But power requirements and run time will depend on the needs of the micro controller in question and storing the data.