How to make HC-05 connect to all users with Android application without pairing?

Question

I want to use the HC-05 Bluetooth module together with the Arduino Nano for an access control system.

I want users with the Android application to click a button to open the boom gate. I have made the connection between the boom gate and the Arduino Nano with a relay module.

The user shouldn't have to manually pair to the bluetooth device.

How can I achieve this?

Must the HC-05 be in master or slave state?

Answer 1

This cannot be achieved with Bluetooth classic. Bluetooth Low Energy has to be used for this purpose.

You have to look at other modules such as ESP32 / ESP32-CAM, HM-10, or Arduino Nano 333 BLE.