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9. Input Devices

In this week’s assignment, I worked on understanding and integrating input devices with a microcontroller. The goal was to sense data from the environment using a sensor and process the information.

Understanding the basics

What are input devices?

An input device is a component that takes information from the environment and sends it to a microcontroller for processing. These devices can detect things like sound, light, temperature, or motion.

Types of Input devices

  • Active Input Devices: Active input devices are sensors that require an external power source to operate. These devices actively send out signals or require power to function and then detect the changes in their environment.

Examples include microphones, ultrasonic sensors, and infrared sensors.

  • Passive Input Devices: Passive input devices do not require an external power source to function. Instead, they detect environmental changes and generate signals based on physical interactions.

Examples include light-dependent resistors(LDR), switch, and capacitor

Choosing the input device

This week I want to try using the sound sensor. The sound sensor I used is an analog microphone module that detects sound waves and converts them into electrical signals. It works by picking up variations in air pressure (caused by sound) and translating them into a changing voltage output.

The sensor has three main pins:

  • VCC – Power supply (3.3V or 5V)

  • GND – Ground

  • AOUT (Analog Output) – Provides a varying voltage based on sound intensity

Sound sensor

For this week assignment make music interactive lights. I was inspired by interactive light installations that respond to music and ambient sounds. Many artists and designers use sound-reactive LEDs in art exhibitions, concerts, and public spaces to create immersive experiences. I wanted to replicate this concept on a smaller scale to understand how it works.

As i was already familiar with Arduino I tried testing the sensor on that first. So based on the intensity of the sound the leds respond to it by turing on or off

Implementing on a Custom

Using Xiao

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

Compares Sound Level to Thresholds:

  • If the sound level is very high (>700), all LEDs turn on.
  • If the sound level is moderately high (600-700), three LEDs turn on.
  • If the sound level is medium (500-600), two LEDs turn on.
  • If the sound level is low (400-500), only one LED turns on.
  • If the sound level is very low (<400), all LEDs remain off.

Step Response

​In addition to the sound sensor, I explored step response sensors to broaden my understanding of input devices.

I referred to Adrian Torres and Robert Hart's documentation to understand how step response works

These sensors work by sending an electrical pulse and measuring how it changes when an object (like a hand) comes close.

How It Works?

  • The sensor consists of two conductive plates.

  • One plate sends an electrical pulse, while the other receives it.

  • When an object comes near, the capacitance between the plates changes, altering the response signal.

  • The microcontroller measures this change and processes it to determine proximity or touch.

Testing Step Respose

To test step response, I used two copper plates connected to an Arduino. One plate was connected to pin 4 (output), and the other to A0 (input). The plates act as capacitive sensors, and the system measures the change in electric field coupling between them.

Serial Monitor Test

First, I tested the setup using the Serial Monitor in the Arduino IDE. When the copper plates were brought closer together, the numbers displayed on the serial monitor changed significantly.

This confirmed that the setup was successfully detecting changes in capacitance due to proximity. I used chatgpt to write the code. Prompt:

Serial Plotter Test

Next, I visualized the data using the Serial Plotter in the Arduino IDE. To open the Serial Plotter, go to Tools > Serial Plotter in the Arduino IDE.

Chatgpt Prompt:

The graph displayed the variation in capacitance as the plates moved closer or farther apart, showing clear changes in the readings over time.

When the copper plates are away

When the copper plates were touch together.

Observations

  • When the copper plates were far apart, the readings remained relatively stable at a lower value.
  • As the plates moved closer, the plotted values increased, showing a clear response to proximity.

Exercise files

Below are the files for: