Basic communication between Android and Arduino devices using BLE
This code demostrates the usage of BLE communication (echo test) between Android device and ESP32 (or any other compatible Arduino device)
The samle code shows a list with any available BT device. Then, select your Arduino device (in this case the name of the device is "BLE-ESP32"). After the device is connected, you can send any text from the Android device to the ESP. When the ESP receives the text, it will reply back the same text to the Android device.