koldfront

Soehnle scale usb connection #hardware #programming

Soehnle makes a scale with a wireless display that collects measurements, and can be attached to a computer using usb, called "Body Balance Comfort Select".

Unfortunately the ComfortSelect software is only available for Windows, and when I asked the manufacturer (in 2012) for information so I could write my own software for Linux, they declined.

So, I installed Virtualbox, got a test image from Microsoft, and used usbmon to capture the communication between the Windows software and the scale.

I'm no expert in this (having only connected to a simple eBuddy before), but so far it looks like the communication is done via bulk transfers.

Update: I have now written a small program that can list the users registered on the scale, and dump the measurements for a user.

It only dumps date + weight, because I don't know what the two remaining 16-bit values are (probably some conductance measurement or similar).

Finally I can get a graph without having to type in the weight every day!

Incidently, it has memory for more than 6 years of measurements (and it keeps them when batteries are removed), which isn't surprising (each measurement takes up 10 bytes) but stupider things have been seen...