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10. Output Devices

Understanding the basics

What are Output devices?

Output devices are components that take signals from a microcontroller or computer and turn them into actions. These actions can be light, sound, movement, heat, or display.

Types of Input devices

Visual Output Devices (Show Light or Images)

  • LEDs – Light-emitting diodes that turn on/off or change brightness.

  • LCD/OLED Displays – Show text, images, or graphics.

  • Projectors – Display visuals on a larger screen.

Motion Output Devices (Create Movement)

  • Servo Motors – Move in precise angles, used in robotics.

  • DC Motors – Rotate continuously, used in fans or wheels.

  • Stepper Motors – Move in steps, useful for CNC machines and 3D printers.

Audio Output Devices (Produce Sound)

  • Buzzers – Create simple beeps or tones.

  • Speakers – Play music or voice sounds.

Electromechanical Output Devices (Control Other Components)

  • Relays – Switch high-power devices on/off using a small signal.

Choosing the input device

The goal of this assignment is to integrate an output device with a microcontroller board and program it to perform a specific function. For this task, I have chosen to use a servo motor as the output device.

Understanding the mechanism

A servo motor is a type of motor that moves to a specific angle instead of rotating continuously like a regular motor. It is controlled by sending PWM (Pulse Width Modulation) signals from a microcontroller.

It works using a small motor, gears, and a position sensor. When the microcontroller sends a signal, the motor adjusts its position accordingly and holds it steady. This makes servo motors ideal for tasks that need precise movement, like robotics, automation, and control systems.

Connections in Servo Motor

The sensor has three main pins:

  • Power (VCC/Red Wire)
  • Ground (GND/Black or Brown Wire)
  • Control Signal (PWM/Yellow or Orange Wire)

Types of Servo Motors

Based on the application servo motors are classified into different types:

  • AC Servo Motor – Operates using AC power, used in industrial applications.

  • DC Servo Motor – Operates using DC power, commonly used in small robotic systems.

  • Brushless DC Servo Motor – Offers high efficiency and durability, used in high-performance applications.

  • Positional Rotation Servo Motor – Moves within a fixed range (0° to 180°), used for precise positioning.

  • Continuous Rotation Servo Motor – Rotates in either direction without a fixed stop, used in wheels and conveyor systems.

  • Linear Servo Motor – Converts rotational motion into linear movement, useful for actuators and sliding systems.

Individual Assignment

To do this I will be using the breakout board that i made during week 8

Before writing any code, I first connected the servo motor to the XIAO RP2040.

First Attempt: Controlling the Servo with Fixed Angles

I started with a simple program to move the servo to 0°, 90°, and 180° with a delay between each movement.

I began by writing a simple program to control the servo motor at specific angles.

The idea was to move the servo to 0°, 90°, and 180° with a delay in between. This was meant to verify that the servo was responding correctly to commands

Issue encountered: In Arduino IDE the correct port was not automatically selected. To fix this I manually selected the port from Tools > Port.

Second Attempt: Controlling the Servo with Fixed Angles

To achieve smoother motion, I modified the code so that the servo would move gradually from 0° to 180° and back, instead of jumping directly between positions.

This was done using a for loop to change the servo position incrementally

Solenoid

I also tried experimenting with solenoid. A solenoid is an electromechanical device that converts electrical energy into linear motion. When an electric current passes through the coil, it creates a magnetic field, which moves a metal plunger inside the coil.

To understand solenoid mechanisms better, I referred to an online guide on making solenoid coils Instructables link. This helped me learn how the coil is wound and how solenoids function practically

I started off by taking a plastic tube. For which i used a pen and cut of its edges.

To support the sides of the pen. I made a donut shaped laser cut out.

Then I took an enamel-coated copper wire and wrapped it around a plastic tube. Leave the two wire ends ends exposed for electrical connections.

Ensured the wire is wound tightly and neatly to maximize the efficiency of the electromagnetic field.

Then I scrapped off the enamel coating at the wire ends using a blade to ensure proper connectivity.

I used a DC Voltage motor and set its value to 12V.

Then I connected the two ends of the wire to the pins

I inserted an nail inside the coil to enhance the magnetic effect. Observed the nail for movement, expecting it to get pulled inside the coil due to the magnetic field.

Learnings

Even though the solenoid did not work as expected, I gained important insights into the challenges of working with electromagnets and solenoids. Key takeaways:

  • The number of coil turns and power source selection are crucial for proper functioning.
  • The length-to-diameter ratio of the solenoid impacts efficiency—shorter, thicker coils often work better
  • Magnetic field strength is directly proportional to the current and the number of turns, so optimizing these factors is key.

8x8 Matrix

Exercise files

Below are the files for: