On August 4 a patent was filed by Nintendo detailing what’s inside Wii U’s tablet controller, and it looks as though some of what we already know has been confirmed along a bit of interesting tech as well.
Dug up by NeoGAF, the schematics suggest the tablet contains a magnetometer, which if like the one contained in Sony’s PS Move, will likely be used for calibration. Magnetometers seem to be becoming standard in tech of late, especially with smartphones, and even Sony’s PS Vita will also contain one for motion sensing.
The tablet also features a built-in microphone ans speaker, and a bit of flash memory like with the Wii controller. The diagrams don’t show how much flash memory is included, and while known about for a while, Nintendo has yet to discuss how much will be included.
It also appears to have rechargeable lithium-ion battery built-in, which would not be too surprising.
You can look over the schematics through here.