This tutorial demonstrates how to interface a servo motor with an 8051 microcontroller, allowing precise control over the motor’s position and movement.

One of the most commonly used motors for precise angular movement is the stepper motor. Its advantage lies in its ability to control the angular position without requiring any feedback mechanism. It finds widespread use in industrial and commercial applications, moreover, it is commonly employed in drive systems such as robots and washing machines.

Contents

0.1 Stepper Motor

1 Connection
2 8051 Interface Servo C code
- 2.1 Code Explanation
- 2.2 NEXT
  - 2.2.1 Explore more

Stepper Motor

We are using a unipolar stepper motor, which can be either unipolar or bipolar. In this case, we are utilizing a unipolar stepper motor. It comprises six wires, with four connected to the motor’s coil and two serving as common wires.

Certainly! A stepper motor is an electromechanical device that converts electrical pulses into precise mechanical movements. It operates by dividing a full rotation into a number of equal steps. These motors are commonly used when precise control over the rotation angle is required, without the need for feedback mechanisms.

Stepper motors come in various types, including bipolar and unipolar configurations. In a bipolar stepper motor, current flows through two coils, while in a unipolar stepper motor, each coil has a center tap connected to a common wire.

One of the main advantages of stepper motors is their ability to move in precise increments, making them suitable for applications such as robotics, 3D printers, CNC machines, and automated systems.

Moreover, stepper motors offer excellent torque at low speeds, providing smooth and accurate motion control. They are also relatively simple to control using microcontrollers or dedicated motor control circuits.

Overall, stepper motors are versatile devices with a wide range of applications, from industrial automation to consumer electronics, owing to their precise control, reliability, and ease of use.

Connection

8051 Interface Servo C code

GitHub Source: https://github.com/ArunEworld/Embedded/blob/master/8051-MCU/8051-Interface/8051-Interface-Servo-Motor.c

// C program for interfacing servo motor with 8051 microcontroller
// www.ArunEworld.com

#include<reg51.h>

sbit output=P2^0;

void msdelay(unsigned int time) // Function for creating delay in milliseconds.
{
    unsigned i,j ;
    for(i=0;i<time;i++)
        for(j=0;j<1275;j++);
}

void servo_delay(int times) // Creating Delay in multiple of 50us using 8051 Timers
{
    int m;
    for(m=0;m<times;m++)
    {
        TH0=0xFF;
        TL0=0xD2;
        TR0=1;
        while(TF0==0);
        TF0=0;
        TR0=0;
    }
}

void main()
{
    int n;
    TMOD=0x01; // Selecting Timer 0, Mode 1
    output=0;
    
    while(1)
    {
        for(n=13;n<28;n=n+2)
        {
            output=1;
            servo_delay(n);
            output=0;
            servo_delay(260);
            msdelay(200);
        }
    }
}

Code Explanation

Component	Explanation
Header File	`#include<reg51.h>` includes the header file specific to the 8051 microcontroller family, providing access to register definitions and configurations.
Pin Declaration	`sbit output = P2^0;` declares `output` as a single bit variable and assigns it to pin 0 of port 2. This pin is used to control the servo motor.
Delay Functions	`msdelay(unsigned int time)` creates a delay in milliseconds using nested loops. `servo_delay(int times)` creates a delay in multiples of 50 microseconds using Timer 0 of the 8051 microcontroller.
Main Function	`void main()` is the main function of the program.
Timer Configuration	`TMOD=0x01;` configures Timer 0 in Mode 1, which is an 8-bit timer mode.
Loop	The `while(1)` loop continuously rotates the servo motor back and forth within a certain angle range.
Servo Control	Inside the loop, the `for` loop adjusts the pulse width sent to the servo motor by changing the delay value (`n`). The `output` pin is set high and low accordingly to generate the desired pulse width.
Delay and Timing	`servo_delay` is used to control the pulse width applied to the servo motor, while `msdelay` controls the speed of the servo motor’s movement.