Laptop-based HMI For DC Motor Speed and Direction Control using Arduino

This project establishes a computer-controlled human-machine interface (HMI) for manipulating the operational behavior of a direct current motor. At the core of the system is an Arduino Uno board connected to a laptop via a USB interface. The user interacts with a custom graphical software environment built in Processing, running on the laptop. Commands for motor speed and rotational direction are sent from the laptop over the USB serial communication link to the Arduino Uno. The Arduino interprets these serial instructions and translates them into appropriate digital control signals. Because the microcontroller pins cannot supply enough current to directly drive a motor, an L293D motor driver IC (IC1) is employed as an intermediate power stage. The L293D safely routes high-current power from a dedicated 9V external power supply to the DC motor, while using low-current logic inputs from the Arduino to control state and direction. Pulse-width modulation (PWM) generated by the Arduino varies the effective voltage delivered to the motor terminals through the driver IC, allowing smooth speed adjustments. A 2-pin 5.08mm pitch plug-in screw terminal block connector secures the motor leads to the broader circuit on a breadboard using connecting wires. By separating the motor's 9V supply from the Arduino's logic power, the system prevents electrical noise and voltage drops from resetting the microcontroller.