Group assignment: Probe an input device’s analog levels and digital signals, document the work, and write a personal reflection on the individual page.

Team: Manuel Ayala-Chauvin, Sandra Nuñez-Torres
Institution: Fablab - Universidad Tecnológica Indoamérica
Year: 2025

1. Connection Diagram of the HCSR04 Sensor

We used the HCSR04 ultrasonic sensor connected to an Arduino Uno board as follows:

• VCC → 5V
• GND → GND
• TRIG → Pin 9
• ECHO → Pin 10

Wokwi simulation

2. Code for Data Acquisition

The following Arduino code measures distance using the sensor and prints the results to the serial monitor:

				
			#define TRIG_PIN 9
			#define ECHO_PIN 10

			
			void setup() {
			  Serial.begin(9600);
			  pinMode(TRIG_PIN, OUTPUT);
			  pinMode(ECHO_PIN, INPUT);
			}

			
			void loop() {
			  digitalWrite(TRIG_PIN, LOW);
			  delayMicroseconds(2);
			  digitalWrite(TRIG_PIN, HIGH);
			  delayMicroseconds(10);
			  digitalWrite(TRIG_PIN, LOW);

			
			  long duration = pulseIn(ECHO_PIN, HIGH);
			  float distance = duration * 0.034 / 2;

			
			  Serial.print("Distance: ");
			  Serial.print(distance);
			  Serial.println(" cm");
			  delay(500);
			}
				

3. Measured Data

We placed different objects at various distances in front of the sensor and recorded the measurements. The readings were consistent, with minimal error at short distances.

4. Oscilloscope Visualization

We connected the ECHO pin to the oscilloscope to observe the digital signals generated by the sensor. This allowed us to analyze the pulses produced for each measurement.

5. Test Video

We recorded a short video showing the full setup and real-time signal output:

Watch the test video

Group Reflection

This assignment helped us understand how sensors convert physical phenomena into digital data and how to visualize these signals using an oscilloscope. Team collaboration was key to sharing ideas, troubleshooting, and completing the project effectively.

Individual Reflection (for personal page)

I gained a better understanding of how to capture and interpret digital signals and how sensor data can be processed in physical computing projects. I also learned the importance of sensor response time in accurate measurements.

Individual Assignment: Measure Something

Objective

The primary objective of this individual assignment is to implement a real-world measurement using a sensor interfaced with a custom-designed microcontroller board. The specific task is to detect sound using a digital sensor and to process this data for a visual and logged response. By doing so, the project not only demonstrates the ability to capture a physical event but also showcases the integration between hardware components and software logic. This setup can serve as a foundational element for more complex systems that rely on environmental sensing and user interaction.

Sensor Used: KY-038

The sensor selected for this task is the KY-038, which is a sound detection module equipped with an electret microphone. The KY-038 module is widely used in prototyping and educational electronics due to its simplicity, affordability, and clear functionality. The module includes both analog and digital outputs. The analog output provides a continuously variable voltage level based on sound intensity, while the digital output emits a binary HIGH or LOW signal based on whether the detected sound level exceeds a threshold. The threshold can be manually adjusted using the onboard potentiometer, allowing for calibration based on ambient noise conditions or the desired sensitivity level.

This modular sensor is well-suited for projects that involve detecting claps, knocks, or other sudden noises in a room. Its plug-and-play design enables quick testing and integration with Arduino-compatible microcontroller boards or custom-designed boards built around ATmega or other microcontrollers.

Working Principle

The KY-038 sound sensor operates on a straightforward principle. It consists of four main components: an electret microphone, an operational amplifier, a comparator circuit, and an adjustable potentiometer. The microphone captures ambient sound and converts it into a small analog voltage. This signal is then amplified by the operational amplifier to make it more detectable by the comparator.

Wokwi simulation

The comparator takes the amplified signal and compares it to a reference voltage set by the potentiometer. If the signal surpasses this reference threshold, the comparator outputs a HIGH signal on the D0 pin, indicating that a significant sound event has occurred. This digital signal can be used to activate devices such as LEDs, buzzers, or be logged by microcontrollers for further processing.

Code Implementation

The software component of this project is implemented using the Arduino programming environment. The code is designed to initialize the digital pin connected to the KY-038 sensor as an input and the onboard LED as an output. Within the main loop, the code reads the sensor state and determines whether a sound has been detected. If the sensor's digital output is HIGH, indicating a loud sound was detected, the LED is turned on and a message is sent to the serial monitor.

This process allows the user to receive both visual (via the LED) and textual (via serial communication) feedback when a sound is detected. This kind of feedback is useful for debugging and for verifying that the system is functioning correctly.

		  int sensorPin = 2; // KY-038 digital output connected to pin 2
		  int ledPin = 13;   // Onboard LED
		  
		  void setup() {
			pinMode(sensorPin, INPUT);
			pinMode(ledPin, OUTPUT);
			Serial.begin(9600);
		  }
		  
		  void loop() {
			int sensorState = digitalRead(sensorPin);
			if (sensorState == HIGH) {
			  digitalWrite(ledPin, HIGH);
			  Serial.println("Sound detected");
			} else {
			  digitalWrite(ledPin, LOW);
			}
			delay(100);
		  }
			

Wiring and Connections

To properly connect the KY-038 to the microcontroller board, ensure the following pin mapping is used:

• VCC should be connected to the 5V power output of the microcontroller board
• GND must be connected to the ground (GND) pin
• D0 should be connected to a digital input pin on the board (e.g., pin 2)
• LED can be connected to digital pin 13 for visual indication

Always double-check your wiring to avoid incorrect connections which might damage the sensor or yield incorrect readings. Use proper connectors or soldered joints if the circuit is not being assembled on a breadboard.

Data Reading and Observations

Once everything is set up and powered on, the KY-038 sensor actively listens for sound. When a loud noise, such as a hand clap or a tap near the microphone, occurs, the sensor's D0 output goes HIGH. This transition is immediately detected by the microcontroller, which responds by turning on the LED and printing "Sound detected" to the serial monitor.

This real-time response makes the system useful for applications that require instantaneous sound recognition. Moreover, by turning the potentiometer on the sensor, you can adjust how sensitive it is to sound. This is particularly helpful in noisy environments where you want to filter out background noise and focus only on specific, louder sound events.

Demonstration Video

A video demonstrating the working setup is available at the following link. This provides visual confirmation of the behavior described above and helps users understand the sensor’s responsiveness in real-time applications.

Watch Demonstration Video

Conclusion

This project serves as an introductory exercise in the integration of sensors with custom microcontroller platforms. It effectively demonstrates how to detect physical phenomena—specifically sound—using electronic components. The KY-038 sound sensor proves to be a highly useful tool for such applications due to its simplicity, adjustability, and ease of integration.

Through this assignment, we explored key engineering practices such as sensor interfacing, threshold tuning, real-time feedback via LEDs, and debugging using serial communication. These skills are foundational for more advanced embedded systems projects where environmental monitoring or event detection is required. Additionally, this setup can be expanded to interact with other systems such as alarms, data loggers, or wireless transmitters, making it a flexible base for future innovations.