Hi,

As an electronics hobbyists we come across Motor interfacing at some point of our Hobby Days. You may be knowing different kind of Motors available in Market, it depends on your application requirement that you choose either a DC Motor, a Servo or a Stepper. Each motor has some Quality and disadvantages over other. Like DC motor can be High RPM and High torque (using Gear Heads) but DC motors carries problem of Inertia so its not very accurate. You can not make DC motor to rotate by an accurate angle value due to inertia effect. Unlike DC, servo can be controlled with precision in amount of rotation required. Servo motors had High torque also but it can’t be used in Continues rotation scenarios like a Wheel rotation and of course High RPM values can’t be achieved using Servos.

Stepper motor is somewhere between DC and Servo, for instance Stepper motor can take precise turns like Servo in terms of steps per revolution and it can be rotated continually like DC Motors. It does not have That much Torque so can’t be used in High Load situations. So Stepper gives you a middle level solution due to accuracy of Open loop control system and Gives a continues rotation due to Rotor and Stater arrangement like DC motors. So today we are going to see the details of How can we get a stepper motor running ?

Working of Stepper Motor

Like most of the Motors (AC,DC,Servo etc) Stepper motors basic principle is Magnetic Induction or Electromagnetic effect (Remember Faraday !). A rotor rotates in the magnetic field of a stater. Stater is generally a Coil made up of Copper wire, stepper motor can have many number of such coils arranged in a circular shape inside the motor housing. The figure shown above is a 4 Coil Stepper motor. An electric pulse excite a single coil at any time in Full step mode (to be explained later… ) and the rotor (made up of Magnetic material) gets attracted toward the excited Copper coil (Now an Electro Magnet) and this way if we give a proper sequence of pulses to the coils of Stepper we can get a continues rotation in small steps.

A Normal stepper motor can take turns with precision of as high as 0.9 degrees of angular displacement in each step. An illustration of working of Stepper motor is shown in the image below, We hope that you got the working of Steppers, if You still have doubts, comments are always invited …

Now, once you got the inner working of Stepper Motor working its easy for you to make it useful in your next application requirement. There can be many ways to have our Stepper running but using a Micro Controller is certainly an advantage and easy way to do so.

In second part of this tutorial, we will explore how can we Interface our Stepper motor using an AVR Micro-controller and what kind of external circuit requirements are there.

This entry was posted in AVR Sheets, AVR Tutorials, Interfacing Tutorials