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Bluetooth Controlled Robot Using 8051 Microcontroller

Writer's picture: Sanskruti AshtikarSanskruti Ashtikar
Nov 15, 20244 min read

Updated: Jan 23

Introduction


A Bluetooth controlled robot is a versatile project that combines wireless communication and robotics. Using the 8051 microcontroller, this project demonstrates how to control a robot's movement via Bluetooth commands sent from a smartphone. The robot can move forward, backward, left, and right based on the received commands. This project is ideal for learning about wireless communication, motor control, and microcontroller programming.





Components Required



Circuit Diagram


The 8051 microcontroller interfaces with the HC-05 Bluetooth module for wireless communication and the L293D motor driver to control the DC motors.


+5V ----- +5V
          |
          |
        HC-05
        +---+
    +5V |VCC| 
    GND |GND|
    TX  |TXD|------- RXD (P3.0 of 8051)
    RX  |RXD|------- TXD (P3.1 of 8051)
         +---+
L293D Motor Driver
      +---+
1,9  | VCC2 | ----- 12V (Motor Power Supply)
8,16 | VCC1 | ----- +5V
    4,5,12,13 | GND | ----- Ground
  2 | IN1 | ----- P2.0 (8051)
  7 | IN2 | ----- P2.1 (8051)
10 | IN3 | ----- P2.2 (8051)
15 | IN4 | ----- P2.3 (8051)
  3 | OUT1| ----- Motor 1
  6 | OUT2| ----- Motor 1
11 | OUT3| ----- Motor 2
14 | OUT4| ----- Motor 2
      +---+
DC Motors
Motor 1 - Connected to OUT1 and OUT2 of L293D
Motor 2 - Connected to OUT3 and OUT4 of L293D




Pin Connections


  • HC-05 Bluetooth Module:

  • VCC to +5V

  • GND to Ground

  • TXD to RXD (P3.0 of 8051)

  • RXD to TXD (P3.1 of 8051)

  • L293D Motor Driver IC:

  • VCC2 to 12V (Motor Power Supply)

  • VCC1 to +5V

  • GND to Ground

  • IN1 to P2.0 of 8051

  • IN2 to P2.1 of 8051

  • IN3 to P2.2 of 8051

  • IN4 to P2.3 of 8051

  • OUT1 and OUT2 to Motor 1

  • OUT3 and OUT4 to Motor 2


Software Implementation


The code is written in C using Keil uVision IDE. It involves initializing the UART for Bluetooth communication, reading commands from the Bluetooth module, and controlling the motors based on these commands.


#include <reg51.h>
sbit IN1 = P2^0; // Motor 1 IN1
sbit IN2 = P2^1; // Motor 1 IN2
sbit IN3 = P2^2; // Motor 2 IN3
sbit IN4 = P2^3; // Motor 2 IN4
void delay(unsigned int count) {
    int i, j;
    for(i=0; i<count; i++)
        for(j=0; j<1275; j++);
}
void uart_init(void) {
    TMOD = 0x20; // Timer1 in mode 2
    TH1 = 0xFD; // Baud rate 9600
    SCON = 0x50; // 8-bit data, 1 stop bit, REN enabled
    TR1 = 1; // Start Timer1
}
char uart_receive(void) {
    while(RI == 0); // Wait for reception to complete
    RI = 0; // Clear reception interrupt flag
    return SBUF; // Return received character
}
void move_forward() {
    IN1 = 1; IN2 = 0;
    IN3 = 1; IN4 = 0;
}
void move_backward() {
    IN1 = 0; IN2 = 1;
    IN3 = 0; IN4 = 1;
}
void turn_left() {
    IN1 = 0; IN2 = 1;
    IN3 = 1; IN4 = 0;
}


void turn_right() {
    IN1 = 1; IN2 = 0;
    IN3 = 0; IN4 = 1;
}
void stop() {
    IN1 = 0; IN2 = 0;
    IN3 = 0; IN4 = 0;
}
void main() {
    char command;
    
    uart_init(); // Initialize UART
    
    while(1) {
        command = uart_receive(); // Receive command from Bluetooth
        
        switch(command) {
            case 'F': // Forward
                move_forward();
                break;
            case 'B': // Backward
                move_backward();
                break;
            case 'L': // Left
                turn_left();
                break;
            case 'R': // Right
                turn_right();
                break;
            case 'S': // Stop
                stop();
                break;
            default:
                stop();
                break;
        }
        
        delay(100); // Small delay for motor control
    }
}




Explanation


  1. Initialization:

  2. UART Initialization: The uart_init() function configures the UART for Bluetooth communication at a baud rate of 9600.

  3. Receiving Commands:

  4. The uart_receive() function waits for and reads a character from the Bluetooth module via UART.

  5. Motor Control:

  6. Functions like move_forward(), move_backward(), turn_left(), turn_right(), and stop() control the direction of the motors based on the received commands.

  7. Command Processing:

  8. The main loop continuously receives commands and uses a switch-case structure to call the appropriate motor control function based on the command received.


Conclusion


This project demonstrates the use of the 8051 microcontroller to create a Bluetooth controlled robot. The system can receive commands from a smartphone via a Bluetooth module and control the robot's movement accordingly. This project is a great way to learn about wireless communication, motor control, and using microcontrollers in robotics applications.


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