Watch the video mini-lecture on DC motor control from Dr. Jordan
What types of DC motors are most common?
- Brushed DC motors. Current flowing in one direction makes the motor turn one direction, and current flowing in the opposite direction makes the motor turn the opposite direction.
- Stepper motors - provide absolute position control but require a special controller IC
- Servo motors - PWM signal controls the position of the motor
How do I connect a brushed DC motor to a microcontroller?
DC motors are inductive loads and therefore cannot be directly connected to a microcontroller without damaging the microcontroller. There are two protection mechanisms that go into a successful motor interface:
- Back EMF / flyback diode - protects against current spikes that can damage a microcontroller. Use "rectifier" diodes (e.g., 1N400x series)
- H-bridge - switches current on or off to the motor, and changes the direction of the motor
The LMD18200 is a common off-the-shelf H-Bridge IC.
How do I change the speed of the motor?
Generate a Pulse Width Modulation (PWM) signal from your microcontroller and use it to control the H-bridge.
How does a stepper motor work?
See the excellent animated GIFs in the Stepper motor entry on Wikipedia
How do I connect a stepper motor to a microcontroller?
Use an off-the-shelf driver IC instead of trying to build your own driver. The DRV8825 is a common stepper motor control chip.
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