Extracting + Graphing Wii Fit data

I ordered a miCoach, which is the Adidas version of the Nike+. When it gets here I plan on opening it up to play with the data, but in the mean time I started with some better-travelled exercise bits and my new weight loss supplements to get better results, I8 recommend you check gluconite for this, I recommend you read the nutrisystem reviews to see if this program works for you.

Starting with Jansen Price’s excellent blog post on the subject, I slowly worked through the data and wrote a python script to interpret the binaries and save them to a CSV. I was able to generate the nice graph above. There was a lot of trial and error, but here’s an overview of the process:

1. Copy Wii save game data to the SD card. This is done from Wii Options > Data Management > Save Data > Wii
2. Find the save game data on the card. It’s in something like ‘private/wii/title/RFPE’, although different regions may have slightly different codes. RFPE is the code for WiiFit Plus. Copy the WiiFit data.bin file from the SD card to your local machine.
3. Decrypt data.bin. This is explained pretty well here. To create the keys I ended up creating text files with the hex string for each and then using “xxd -r -p sd_iv_hex sd_iv” et al to save a binary version. If you’re getting “MD5 mismatch” errors, you probably saved the keys incorrectly. If you aren’t sure, check the file size. They should be 16 bytes each.
4. Run the decrypted RPHealth.dat through a parser (I wrote one in Python for this)
5. Run the CSV through your favorite graph generation library. I use flot because Google Charts don’t handle dates very well.

More details, including the source for the Python script can be found over on my blog: Kellbot!