It shows the numeric keypad on the screen of the cell phone or tablet, as well as a connection button for the Bluetooth module. Once the connection to the module is achieved and as it is typed on the keyboard, the characters are sent one by one to the electronic system to which the Bluetooth module is connected.

The electronic system can be of any type: the entire range of Arduinos or microcontrollers such as PIC, ATMEL, MOTOROLA, etc.

This application can be used in the implementation of access control systems, power on home automation devices, industrial control, etc.