* A serial debugging cable for your device. '''You will need to make this yourself''', so prior experience with soldering and soldering tools is recommended. (You might be able to make a cable without soldering if you find the right parts, though.)
An USB-UART adapter that will allow you to connect the UART cable from your phone/tablet to your computer.
* A piece of software like screen, PuTTY or CuteCom that will be used to access the output from the USB-UART adapter on the computer.