I spent the afternoon looking for some code I wrote in 2013. I'm glad I found it. Is a little C++ to interface the Beagle Bone (any) to the Adafruit 16-channel, 12 bit PWN servo driver board- the PCA9685- over I2C. I then tried the old upgrade trick on my BBB. It turned out that the device is an A6 model with only 2GB storage in the eMMC, not 4GB like the Rev C production models. I will probably clean that code up and post it to github once it's all pretty.