The easiest way to visualize Arduino Sensor-Data directly on your Android-Device in REALTIME! The App is able to display the values of up to 10 Sensors simultaneously (in Receiver-Mode).
With the new Terminal-Mode you even can send data to your Arduino. The responds will also be shown in the App.
Only required is to load some Code to your Arduino-Board, wire a Bluetooth-Module (like the HC-05) to the Arduino and couple Android-Device and Bluetooth-Module in the System-Preferences.
The App will establish a wireless Bluetooth-Serial-Connection between Arduino and Smartphone.
For a How-To click on the link:
-Bluetooth-Modul (HC-05, HC-06, ...)
The Bluetooth-Module has to be wired as shown at the labeling of the Module (Caution: HC-05 TX has to be wired to Arduino Pin 10 (RX), HC-05 RX has to be wired to Arduino Pin 11(TX)).
The newest versions of Arduino-Code you can find on Github: