Before I found Hackaday, I had already begun working on this project. Much earlier in the year, I first tried reverse engineering a small phone meter called Gmate Smart.

Here is my setup. It required two macs, an iphone, the meter, and a very unique adapter connecting the four.

The meter had four pins, standard for an audio jack with a mic. Two were for power and ground, connected to the iphone running Gmate's app. Another was for the meter's communication with the phone, connected to the Macbook Pro (the only device with a line in). The last was connected to both the phone and the iMac to listen in on the app's communication with the meter.

The results were very interesting. There was a handshake between the app and the meter when it first turned on. Another audible bleep when the strip was plugged in, and another when the blood was applied.

It seemed hopeful, but after close examination of the waves

I decided they were actually digital signals, that would take far too long to reverse engineer. The digital wave patters look cool though.