Hi, this is a frame to convert an Omron M3 blood pressure meter to automatic working, to make a night blood pressure holter while you sleep. There's no modification in the meter, the Arduino controlled servo makes the same as your finger while you are awake.

A basic Arduino code is also attached, I used an Arduino Due I had for other little project but I recommend to use a UNO (you should rename and arrange the input and output variables for convenience), connections are very simple and you can see them in the arduino's webpage (https://www.arduino.cc/en/Tutorial/Sweep). There is also a little code line description in the .txt code file.

Anyway, you can use whatever timed automation with a little servo (SM-S2309S recommended, it fits perfectly in the frame). The servo lever has at its end a little magnetic tape cassette wheel with a soft o-ring or something similar to simulate the soft touch of your finger (see photos). You must cutaway the four thin triangular supports with a cutter, before you can mount the servo

To fix the frame to the blood-pressure meter I addopted a tricky solution with a screw and a nut, try a better one (Arduino board must be unmounted to unmount the meter, see photos). I suggest to mount the Arduino board with only two screws to the top free edge of the frame instead of the front side, so you can unscrew easily. Holes are not provided in STL, it is better to drill them tailor-made.

I tested the Arduino with a 9V battery in order to make the device portable and it didn't work, I had to power the Arduino with the programming cable with a handy transformer.