Today I found a Jawbone UP2 on the street and picked it up. I have no in-depth knowledge about those fitness trackers at all, but I did a bit of research...
From the beginning I was interested in the Lipo battery of the wristband and in getting a use out of it. The first thing I wanted to know was the pinout of the charging connector. But I found no information about that. The next thing I remember was me trying to take the tracker apart.
NOTE: I am currently traveling and have no tools whatsoever. I disassembled this whole tracker just with a big knife and it took me around 20 minutes. This teardown is not professional, nor correct.
I will follow this up as fast as I can. Help is welcome.
Step 1: Disassembly
First I tried to pull and break the wristband apart, but this did not show any sign of opening at all. My next, successful, attempt included cutting the rubber near the metal top away (pic 1).
Afterwards I could pry the bottom plate with a knife away, it bend and broke into multiple pieces. Under the panel were two magnets, left and right of the charging contacts, and two silver circles (pic 2).
The top lid came of in one part, but required more force to do so (pic 3). 3 LED pairs in the middle and a golden pin in the top right corner were the first parts I noticed. The black plastic covering the heart of the fitness tracker was removed with some force after that.
Step 2: Electronics
Without all the covers three separate PCB's, connected with flexible PCB-traces, came into view (pic 1).
I removed the three LED's in the next step. They were only hold in place with foamy tape. Now the first inspection of the chips started. Every PCB of the tree has at least one big black IC on it (pic 2). The two outermost and one in the middle are for data gathering, I would presume. I would continue to say, that the other, shiny, IC's in the middle are for cleaning up the raw data and sending it via BLE. On retrospect I think one of the outer chips is for the Bluetooth stuff, because it minimizes the interference.
The final step I took was to bend up the main PCB's and to reveal the battery (pic 3). On the other side of the power input (middle) was a metal cylinder. In my opinion it looks like a standart sized electret microphone, but this would be stupid. First of all there are smaller versions out there and second, why would a wristband need this?
One of my goals from beginning was to acquire the pinout of the power connector. I tried hard, but with my limited tools I can't do this right now (pic 4). All I can see is that the Lipo battery has three wires: red (positive), white and black (negative). The white wire could be a thermometer or the connection for a second cell of a 2S Lipo. But I strongly believe this is a single cell battery. The three wires all end in a PCB with the charging connections on the other side. My guess is, that the big middle connections of the charger are for power and the small outer connections for data.
Things I forgot:
- The metal pin mentioned in step 2 is a springy, gold plated piece of metal, used as a normally closed switch.
- The PCB assembly gets power through two metal rails on each side of the housing.
This is all I can do at this point in time, but I will continue my research in a few days!