Stepper Motor Stepping Modes

Stepper Motor Connections:
Unipolar motor should have five or six connections depending on the model. If the motor has six connections like the one pictured above, you have to join pins 1 and 2 (red) together and connect them to a (+) 12-24V voltage supply. The remaining pins; a1 (yellow), b1 (black), a2 (orange), b2 (brown) should be connected to a driver (ULN2003 etc).

Stepper Motor Connections

Stepping Modes:

There are several stepping modes that you can use to drive the stepper motor.

• Single Stepping - the simplest mode turns one coil ON at a time. 48 pulses are needed to complete one revolution. Each pulse moves rotor by 7.5 degrees. The following sequence has to be repeated 12 times for motor to complete one revolution.

Pulse	Coil a1	Coil b1	Coil a2	Coil b2
1	ON
2		ON
3			ON
4				ON

• High Torque Stepping - high power / precision mode turns ON two coils on at a time. 48 pulses are needed to complete one revolution. Each pulse moves rotor by 7.5 degrees. The following sequence has to be repeated 12 times for motor to complete one revolution.

Pulse	Coil a1	Coil b1	Coil a2	Coil b2
1	ON	ON
2		ON	ON
3			ON	ON
4	ON			ON

• Half Stepping - stepping is doubled and motor needs 96 pulses to complete one revolution. Each pulse moves rotor by approximately 3.75 degrees. Notice the mix of single stepping mode (lighter green) and high torque mode (darker green).

Pulse	Coil a1	Coil b1	Coil a2	Coil b2
1	ON
2	ON	ON
3		ON
4		ON	ON
5			ON
6			ON	ON
7				ON
8	ON			ON

	- single stepping mode, normal strength, quiet
	- high torque mode, high strength, slightly louder

We have now learnt most of the necessary things regarding a stepper motor. In the next section we will discuss about the various techniques to interface a stepper motor.