In this project, I will show you how to design and develop a Bluetooth Controlled Robot using Arduino, HC-05 Bluetooth Module and L298N Motor Driver Module. On the other end of the Bluetooth Communication, I will be using a Smart Phone and a simple Android App to control the Robotic Car.
Android phone is used as transmitting device and Bluetooth module placed in car is used as receiver. Android phone will transmit command using its in-built Bluetooth to car so that it can move in the required direction like moving forward, reverse, turning left, turning right and stop.
- Arduino UNO
- L298N Motor Driver Module
- HC-05 Bluetooth Module
- Robot Chassis
- 4 x 5V Geared Motors
- Connecting Wires
- Battery Holder
- Power Supply
- Android Phone
- Bluetooth Controller App
I wouldn’t go into the details of the construction of the robot as your robot chassis might be different from mine and you can easily figure it out how to build the robot from the available parts and possible cable management for making the robot more appealing.
Coming to the design of the circuit, first is the HC-05 Bluetooth Module. The +5V and GND pins of the Bluetooth Module are connected to +5V and GND of Arduino.
Since I will be only transmitting data related to the Robot’s movement from Android Phone to Bluetooth Module and do not intend to receive any data from Arduino, I will connect only the TX pin of the Bluetooth Module to RX Pin of Arduino.
This RX pin of Arduino is based on SoftwareSerial library (Pin 2 and Pin 3 are configured as RX and TX on Arduino). The RX pin of the Bluetooth is left open.
Now, the L298N Motor Driver Module. Digital I/O Pins 9 through 12 of Arduino are configured as Input pins of the Motor Driver and are connected to IN1 through IN4 of the L298N Motor Driver Module. Both the Enable Pins are connected to 5V through provided jumper.
The robot chassis which I am using in this Bluetooth Controlled Robot Car project is supplied with 4 geared motors. Since L298N has slots for only two motors, I have joined the left side motors as one set and the right side motors as other set and connected both these sets to the output of L298N Module.
Assemble the robot, make the necessary connections and upload the code to Arduino. If you understood the HC-05 Bluetooth Module tutorial, then understanding the Bluetooth Controlled Robot project is very easy.
First, in the Android App, I have used 5 keys as Forward, Reverse, Left, Right and Stop. The corresponding data associated with each key is as follows:
- Forward – 1
- Reverse – 2
- Left – 3
- Right – 4
- Stop – 5
When a key is pressed, the corresponding data is transmitted to the Bluetooth Module from the Phone over Bluetooth Communication.
In the Arduino code, the Arduino UNO receives any of this data from the Bluetooth Module (as per the key pressed) and performs a simple switch case operation, where each case associated with appropriate instructions to the Motor Driver Input Pins.
For example, if ‘Forward’ key is pressed in the Android Phone, then ‘1’ is transmitted. Arduino will then make IN1 and IN3 as HIGH and IN2 and IN4 as LOW to achieve a forward motion.
Similarly, other keys correspond to appropriate setting of IN1 – IN4 pins.
If you remember the HC-05 Bluetooth Module tutorial, I have used a simple app called Bluetooth Controller, which is installed on an Android Phone to communicate with the Bluetooth Module.
In this project, I have used the same app with modifications in the data to be transmitted.
The code in the code tab below is written to synchronize with the data configured in the Bluetooth Controller App.
Note: You can download the apk file of the app here
HC05 Bluetooth Module
L298N Motor Driver
Bluetooth controlled RC Car
#define IN1 12
#define IN2 11
#define IN3 10
#define IN4 9
//#define EN1 6
//#define EN2 5
SoftwareSerial mySerial(2, 3); // RX, TX
data = mySerial.readStringUntil(‘\n’);
btVal = (data.toInt());
//Serial.print(“BlueTooth Value “);
if (mySerial.available() < 0)
//Serial.println(“No Bluetooth Data “);
- As the range of the Bluetooth Communication is limited (a maximum of 10 meters for class 2 devices for example) the control range of Bluetooth Controlled Robot is also limited.
- Make sure that sufficient power is provided to all the modules especially the Bluetooth Module. If the power is not sufficient, even though the Bluetooth Module powers on, it cannot transmit data or cannot be paired with other Bluetooth devices.
- Low range Mobile Surveillance Devices
- Military Applications (no human intervention)
- Assistive devices (like wheelchairs)
- Home automation