Week 09 Input devices

This week's assignment is about Input Devices. Since my PCB fabrication is not yet completed, I am using an Arduino UNO to complete this week's work.

Learning Objectives

👥 Group Assignment

• Probe an input device(s)'s analog levels and digital signals.

👤 Individual Assignment

• Measure something: add a sensor to a microcontroller board that you have designed and read it.

Learning highlights

Noise Alarm System

1 Introduction

💡1.1 Sound Sensor

A sound sensor is a component that receives sound waves and converts them into electrical signals. It works like a microphone to detect the sound intensity in the surrounding environment. It has various applications, such as noise monitoring, voice control, and security alarms.

Component

📜Sound Sensor Pins

Pin	Function
A0	Analog Output (Range 0~1023)
VCC	Power Input (5V)
G	Ground

💡1.2 Buzzer

A buzzer is an audio signaling device that can be controlled by electrical signals to produce sounds of different frequencies and intensities. It is commonly used for alarms, notifications, and sound feedback applications.

📜Passive Buzzer Pins

Pin	Function
VCC	Power Inpuy (5V)
I\O	Connected to D9 via tone() control
GND	Ground

📜Active Buzzer & Passive Buzzer

Feature	Active Buzzer	Passive Buzzer
Internal Oscillator	✅ Built-in Oscillator	❌ Requires PWM
Control Method	Simply turn on/off with HIGH/LOW signal	Requires PWM signal for sound generation. Requires tone()
Sound Types	Fixed frequency	Can produce multiple tones and melodies
Sound Modulation	❌ Fixed Frequency	✅ Can Play Melodies
Wiring	Directly Connect to Arduino	Requires PWM Control
Common Uses	Alarms, simple notifications	Music tones, sound effects

🛠2 Component Introduction

2.1 Main Hardware

Component	Function
Arduino UNO	Controls the entire system
Sound Sensor	Detects sound intensity in the environment
Passive Buzzer	Generates alarm sounds
Jumper Wires	Connects components
Breadboard	Used for circuit assembly

3 Circuit Connections

3.1 Connecting the Sound Sensor

Sound Sensor	Arduino
A0	A0
VCC	5V
G	GND

3.2 Connecting the Passive Buzzer

Passive Buzzer	Arduino
VCC	5V
I/O	D9
GND	GND

4 Arduino Code

#define SOUND_SENSOR_AO A0
#define BUZZER_PIN 9

int threshold = 600;

void setup() {
    pinMode(BUZZER_PIN, OUTPUT);
    Serial.begin(9600);
}

void loop() {
    int soundLevel = analogRead(SOUND_SENSOR_AO);
    Serial.print("Sound Intensity: ");
    Serial.println(soundLevel);
    delay(10);
    if (soundLevel > threshold) {
        tone(BUZZER_PIN, 3000);
    } else {
        noTone(BUZZER_PIN);
    }
    delay(100);
}
    

5 Compilation & Testing

Upload the code and test it by monitoring sound intensity in the Serial Monitor.

🔍 Buzzer signal is unstable

Issue	Cause	Solution
Buzzer keeps beeping	Threshold too low or sensor too sensitive	Adjust threshold (e.g., set to 400)
No sound from buzzer	Sound level below threshold	Increase sound source or lower threshold
Unstable sensor values	Connection issue or noise interference	Check wiring and minimize interference

⚙️Buzzer Keeps Beeping

Issue	Possible Cause	Solution
Buzzing too frequently	Sound sensor threshold too low	Increase the threshold value in the code.
Incorrect buzzer type usage	Using passive buzzer with digitalWrite(HIGH)	Use tone(BUZZER_PIN, frequency) for passive buzzers.
Incorrect wiring	Incorrect VCC or GND connection	Verify the buzzer’s VCC and GND connections to Arduino.
Unstable sensor values	Connection issue or noise interference	Check wiring and minimize interference

Code01 for this week

Upload and Run Arduino Program

Step-by-Step Guide:

1. 🔌 Connect the Arduino Board: Use a USB cable to connect the Arduino to computer.
2. 🖥 Open Arduino IDEArduino official website.
3. ⚙️ Select Board & Port:
   • Go to Tools → Board and select your Arduino Uno.
   • Go to Tools → Port and select the correct port COM5.
4. 📋 Code: Open the code.
5. ✅ Compile & Upload Code:
   • Click the ✔️ (checkmark icon) to verify the code.
   • Click the ⬆️ (upload icon) to upload the code.
6. 📟 Open Serial Monitor:
   • Go to Tools → Serial Monitor .(shift+alt+M)
   • Set baud rate to 9600.
   • Check code