How "Hackable" are the smartthings Multipurpose Sensor?

Can anybody confirm if the new smartthings Multipurpose Sensor

have “wirefriendly” PCB connectors like others I saw on the market:

No, they do not. I’m sure you could hack at it but we don’t provide connectors for you to integrate other solutions. Fibaro and Ecolink sensors have these.


They don’t have connectors like the Ecolink or Monoprice sensors. You could get creative with a soldering iron, but you’d ruin a good sensor.


…or gain flexibillity:

That video is what triggered the question: thanks to both for the fast answer.
I always being a big fun of dividing tasks in smaller specialized units and divide the protocol transmission electronic from the actual hardware just open up a bunch of different scenario and uses.


Yep, The very first problem that I was trying to solve was the limited temperatures/distances supported by IoT devices in general. Using dedicated outdoors solid package seem a no brainer to me and use the ZWave/zigbee sensor as a “IoT gateway” (plus I love to always keep the original package as a separated back-up alternative to control something so critical).
I know the STMP are not the ideal choice for something like this but since they are part of the ST bundle I was curios to know if they were at least suitable.
They could even repackage one of those switches as “generic IoT gateway” exactly for these kind of hybrid solutions to use in traditional electric boxes but they don’t seem to really love much the hack attitude.

If you do use the aux terms on a contact, you still have to have the magnet attached to the contact as both must be closed to show a closed. At least this is the way it is with the monoprice contacts.

Also, instead of using the outside magnet to keep the reed switch closed you could use one of those tiny super magnets that are about the diameter of a pencil and half the thickness of a dime. Stick that on the inside of the plastic casing.

I read that on here somewhere that the magnet had to be close in order for the terminals to be closed too as there was just one reading (open/closed) for both the reed/magnet and terminals.

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Yes, that makes sense. I guess what I read was incorrect.

So, would I be able to hack together a battery operated smoke alarm’s 2 beeper leads to a contact sensors terminals? Thus, when the smoke alarm beeps the contact sensor’s terminals would be closed from the closed loop thru the smoke alarm.

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I can see the advantage of hooking up a IoT module to external hardware only If you have a very specialized (i.e. expensive, precise, that work in specific condition only) piece of your infrastructure that you want connect to your automation system.
Beside that t the market already have zwave smoke alarms.
But if you want just tinker around and see if playing around spark new idea and concept Im all for it.

Dear sir I could use your services and knowledge at some point.
That sentence made my nerdsenses start tingle.

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It was suppose to be a compliment.
Your reply was “overly” technical and I felt you weren’t really answer to nobody but to yourself and the to the nobility of the “Problem”.
Take one to know one

Hi all, having just taken one of these apart I can say they are not easily hackable.

For starters there is no reed switch, instead they use a Hall Effect Sensor, situated centrally up the edge indicated by the alignment marks for the magnet. This sensor look like a surface mount transistor and on mine has the text “YAAH” which yielded nothing useful to me on Google. It is marked as IC4 on the PCB and measures a mere 3.0x1.7mm (yep it’s tiny!!)

If you apply power to the sensor you get the following readings on the output leg…

You are going to need some nerve and a very steady hand to connect a wire to the output leg so you can toggle the state manually.

Personally I’m not rushing to trash my sensor as there are better options

I came across this conversation while contemplating hacking my ST Multipurpose V3 sensor. simspos’s post is quite close to what I found, with a couple of small variations and one important one that may be due to the version difference (My note refers to the V3 sensor - the picture above and previous posts are about an earlier version).

  • The part number I found on the Hall sensor was 3TAH (nothing useful found on this number via google). It does not have an IC number label on my circuit board.
  • It is a 3 pin Hall effect sensor.
  • The pin on one side by itself is ground.
  • The pin away from the edge of the board on the other side of the sensor is +3V (supply).
  • The pin closest to the edge of the board is signal out.
  • (the big difference) The signal pin is low (0V) when a magnet is nearby and high (3V) when the magnet is far away (opposite what was noted previously).
  • To hack this, you will need to remove the hall sensor chip - otherwise, you will be fighting the output of the hall sensor and will kill the battery as was noted above.
  • I removed the sensor chip. The signal input to the controller is a high impedance input to the controller. If I connect it to +3V through a 1Meg-Ohm resistor, the SmartThings hub reports it to be “open”. If I connect it to 0V through the same 1Meg-Ohm resistor, it switches to “closed”. If I leave the pin disconnected, it stays “open” or “closed”, but even attaching my DVM to measure voltage on the input with respect to ground was enough to flip it to “closed” (probably around a 1Meg-Ohm impedance).
  • To hack this, I plan to use a pull up resistor large enough to be a negligible current for the battery and a reed switch (or collection of them in series) that when closed pull the sensor pin low.
  • Since I am powering mine with a 3.3V supply derived from a USB power source, I’ll use a 5K or 10K-Ohm resistor. If I were using the button battery on this unit, I would have chosen a resistor of 100K-Ohm or larger to draw less than what the rest of the sensor draws.
  • Here is a screen shot of the pull up resistor described