I need to set up my android tab to act as a keyboard for my raspberry pi 2 b+. I have the 7 inch touchscreen mount on the raspberry pi already so I don't need a display. I also have a USB to micro USB coming out of the pi and into the tablet to connect them. Is there any way of setting it up?
The simple answer: No, a stock android device cannot act as a keyboard.
Complex answer: According to this this question you can modify the kernel on some android devices to make it act as a HID device and be a keyboard.
The code is on github.
I would not recommend it unless you have experience rooting your tablet and running non-stock android on it. Get a cheap USB keyboard.