HC-05 Configuration with Arduino

Follow the steps below in order to set the HC-05 module in AT command mode:

Step 1

Connect the Arduino (without HC-05 module) to the computer and run empty code.

Step 2

Disconnect the Arduino from the computer, wire the HC-05 module according the diagram below, then while pressing the button on the ZS-040 break-out board, connect the Arduino to the computer again. Now, The red LED on the ZS-040 break-out board must be blinking in 0.5Hz (one second on, one second off).

Step 3

Run the sketch. Open the Arduino serial monitor, set baud rate to 38400 and choose both NL & CR for line ending. Type AT, then press enter. You should see OK. Now, you can configure your HC-05 module with AT commands. 🎉

Note 1. I've used Clion + PlatformIO as IDE. But using the official Arduino IDE would be ok as well.

Note 2. To make the HC-05 module respond to all AT commands, keep the button on the ZS-040 break-out board pressed while entering commands.