How to Control Servo Motors via Bluetooth with Node MCU and BT Lab App

Hello, reader!

In this post, I will explain how to control multiple servo motors via Bluetooth using a Node MCU and the BT Lab app. You can apply this method to various projects, such as an Arduino robotic arm, fan speed control, and more. And you can also use an Arduino Board  (such as an Arduino Uno or Arduino Nano) with a few modifications in the code.

Required Components for this project :

• Node MCU or Arduino Board
• HC-06 Bluetooth Module
• Two 9g Servo Motors
• Jumper Wires

Use the diagram below to assemble the components correctly.

Download Diagram

You can download the sample code using the link below :

Download Code

Full code is available

#include <Servo.h> 

Servo servo1;
Servo servo2;

#define SERVO1_PIN D4
#define SERVO2_PIN D3
String buffer;

void setup() {
 
  servo1.attach(SERVO1_PIN , 500 , 2400);
  servo2.attach(SERVO2_PIN , 500 , 2400);
}

void loop() {

if(Serial.available()){
  char data = Serial.read();

  if(data == '\n'){
    writeToServo(buffer);
    buffer = "";
  }else{
    buffer = buffer + data;
  }
}

}

void writeToServo(String value){
  String tag = value.substring(0,2);
  String rest = value.substring(2);
  int angle = rest.toInt();


  if(tag == "S1"){
    servo1.write(angle);
  }
  else if(tag == "S2"){
    servo2.write(angle);
  }
}

Make the following changes in the code when using an Arduino:

#include <Servo.h>

Servo servo1;
Servo servo2;

#define SERVO1_PIN 9
#define SERVO2_PIN 10
String buffer;

void setup() {
 
  servo1.attach(SERVO1_PIN);
  servo2.attach(SERVO2_PIN);
}

Important Note: 

Disconnect the TX and RX pins on your Bluetooth module before uploading the code.

Next Configuring the BT Lab App for This Project

Step 1: 

Install the BT Lab App.

If you don’t have the BT Lab app, install it from play store using the link below.

BT Lab

Step 2:

Open the BT Lab app.

Click the plus (+) icon at the bottom of the screen.

Step 3 :

Click Add Seekbar option.

Fill in the details as follows:

• Controller Name  ->  Servo 1
• Main Tag  ->  S1
• Max Value  ->  180

Click the Add button.

Now, you will see a Seekbar in the BT Lab app.

Step 4:

Add Another Seekbar

Repeat the previous steps and create another Seekbar with the following details.

• Controller Name: Servo 2
• Main Tag: S2
• Max Value: 180

Now, you should see two Seekbars in the BT Lab app.

Step 5 :

Connecting BT Lab to Your Bluetooth Module

Click the Connect button at the top-right corner of the BT Lab app.

Select your Bluetooth module from the list.

    Note: To see your Bluetooth module in the list, you must first pair it with your phone.

Controlling the Servo Motors

Once the connection is established, move the Seekbars in the BT Lab app to control the servo motors and enjoy it.😉

This method allows you to control multiple servo motors using Bluetooth with an Arduino or NodeMCU.

Watch the Video Tutorial

For better understanding, watch the video below.

In this post I explain how to control multiple servo motors with via bluetooth with BT Lab app. I hope you find it helpful in your arduino projects. 

Thank you for reading this article!