The Arduino, Bluetooth module (check your specs, some HC-05, and HC-06 may come on a breakout board expecting 5V), and USB Host shield all run off of 3.3V, but devices you want to plug into the ...

This is a simple project. It uses an Android device to switch an LED driven by the Arduino. Connectivity is provided by the Bluetooth module inserted in the breadboard. But one look at the UI on th… ...