HC-05 Bluetooth link with zero code
So you want to two HC-05 modules to automatically connect together, as soon as they’re powered up and with zero code? Well this is your lucky day since this can be done using the AT+BIND command.
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Let’s do this thing!
For this, you will need:
- 1 Arduino (I’m using UNO)
- 2 HC-05 modules
- 1 breadboard
- Wires
- Arduino IDE (I’m using version 1.0.5-r2)
Step 1 – Code and Wires
To bind the two HC-05s, we will need to input AT commands manually which can be done using this simple code made by techbitar.
1.1 Upload the code to your Arduino.
1.2 Using one of your 2 HC-05, follow very carefully the wiring instructions (this is where most people make mistakes.)
 Note that the pins layout on your HC-05 might be different so read the pin label and be sure to connect the right ones.
Step 2 – Configure the Slave
2.1 Make sure the power wire(5.0v or 3.0v) is disconnected from the HC-05
2.2 Make sure the Key wire is connected to pin 9
2.3 In the Arduino IDE, goto the Tools\Serial Monitor menu
2.4 The two following settings are correctly set (at the bottom right of the window):
2.4.1 Line ending should be set to “Both NL & CR”
2.4.2 Baud speed should be set to “9600 baud”
Note: f you had to modify those settings, I suggest to close and re-open the Serial Monitor dialog
For more detail: HC-05 Bluetooth link with zero code
