The typical dc brushed motor has two terminal, positive and negative. To make the motor run we just need to plug in the two terminals with a dc power supply.
But what if we want the motor to run at different speed? Bear in mind the speed of motor is depend on the voltage supply to the motor. Speed of motor is linearly proportional to amount of voltage supply.
Generally, there are several methods can varies the speed of motor such as potential divider method and pulse-width modulation. Potentiometer is used for application of potential divider to control motor speed, whereas pulse-width modulation is generated from a microcontroller.
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| pulse-width modulation |
To do so, we need to have a microcontroller chip and a motor driver chip, L293D. This L293D can used to control the speed and direction of two dc brushed motors.
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| pinout of L293D |
From the pin-out diagram above, output 1 and output 2 is connect motor 1, whereas output 3 and 4 is connect to another dc motor, motor 2. Input 1, 2, 3, and 4 each has to connect to pin of microcontroller. These four pins are used to give signal to L293D to control the rotational direction of motor. Enable 1 is the PWM signal port for motor 1, enable 2 for motor 2. These two port have to connect to the PWM output port of the microcontroller.
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