How to receive data from an external device (Android)

Hello, well i'm new here and i don't know if it's the right place to post.

Okay i need help on how to receive data from an external device (Android)... like what are the commands to receive data..

Thanks in advance.. :slight_smile:

Data from Android is usually serial via Bluetooth. You might start here

and you might find the following background notes useful.

http://homepages.ihug.com.au/~npyner/Arduino/GUIDE_2BT.pdf
http://homepages.ihug.com.au/~npyner/Arduino/BT_2_WAY.ino

I will add a link to the project from myself, which shows data exchange over Bluetooth between the Android phone and Arduino UNO+TFT shield+Bluetooth module (HC-06).
Link to the project: https://www.instructables.com/id/Unique-Arduino-TFT-Shield-Arduino-Bluetooth-Camera/