🔍 LDR Sensor Module - 4 pin

During this assignment, I gained practical experience working with input devices, specifically the ultrasonic sensor and the LDR sensor. We started by programming the ultrasonic sensor and used the Serial Monitor in the Arduino IDE to observe the distance data in real time. This allowed me to clearly understand how the sensor captures and transmits information.

Additionally, we used the Serial Plotter, which provided a graphical representation of the data. This visualization made it easier to analyze how the values changed over time and helped me better interpret the sensor behavior.

Overall, this experience helped me understand how to read, analyze, and visualize input data from sensors, reinforcing my knowledge in embedded programming and real-world interaction with electronic systems. ⚙️📊

Individual Group Assignment Reflection

During the group assignment for the Input Devices week, we worked with an instructor-provided microcontroller board FAB XIAO developed by Adrian Torres to better understand how input devices communicate with embedded systems. In this activity, we tested a temperature sensor connected to the board and used Arduino IDE to upload the program and monitor the sensor data through the Serial Monitor in real time. This experience helped me understand how a microcontroller reads sensor information, processes the signals, and converts them into readable digital data for user monitoring and analysis. Additionally, the assignment reinforced my understanding of sensor integration, serial communication, debugging, and the importance of combining both hardware and software tools to validate the operation of embedded electronic systems.

Individual Assignment

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

Introduction

In this individual assignment, I focused on working with different input devices to understand how electronic systems can interact with the real world. For this purpose, I used two sensors: the HC-SR04 Ultrasonic Sensor,DHT11 Temperature Sensor,.

Each of these sensors allowed me to explore different types of input signals. The ultrasonic sensor was used to measure distance, the TCRT5000 helped detect proximity or line tracking based on infrared reflection, and the touch sensor enabled interaction through physical contact. Notably, the Ultrasonic will be especially important for my final project, as it will be used as part of the detection system.

📟PCB Components

The PCB integrates the SEEED STUDIO XIAO RP2040 as the main microcontroller, connected to supporting components and external interfaces for sensor integration. In this project, I incorporated an HC-SR04 ultrasonic sensor for distance measurement and a humidity and temperature sensor to collect environmental data in real time. These input devices allow the microcontroller to read and process different types of sensor information, transforming physical measurements into digital data that can later be monitored, analyzed, or used for interactive embedded system applications. Together, the PCB and sensors create a functional electronic system focused on environmental sensing and distance detection. ⚙️📡⚙️📡

⚙️1. Programming Process: Ultrasonic sensor(Arduino IDE)

Programming Process: Potentiometer Reading with Arduinio IDE

⚙️1.1 I made a Simple Scetch

In this step, I created a simple sketch to represent the connection between the XIAO ESP32 S3 and the DHT11 temperature and humidity sensor. The diagram defines the basic wiring, connecting VCC to 3.3V, GND to GND, and the DATA pin to a digital GPIO of the microcontroller.

This sketch helped me clearly understand how the sensor communicates with the ESP32 S3 using a single data line, where both temperature and humidity values are transmitted. It also allowed me to verify the correct pin configuration before implementing the physical circuit.🌡️💧⚙️

📈1.2 Simulation of the circuit:

Before testing the physical hardware, I simulated the electronic circuit using the Wokwi platform to verify the behavior of the SEEED STUDIO XIAO RP2040 together with the HC-SR04 ultrasonic sensor. In the simulation, the ultrasonic sensor was connected to the microcontroller using the TRIG and ECHO pins to measure distance values. The Arduino code generated the trigger pulse, received the echo response, and calculated the detected distance based on the travel time of the ultrasonic signal. Through the Serial Monitor, the measured values could be visualized in real time, allowing me to confirm that the sensor communication and signal processing were functioning correctly before implementing the circuit on the real PCB. This simulation stage helped me validate the wiring connections, debug the code logic, and better understand how the ultrasonic sensor interacts with the microcontroller in an embedded input device system.

⚙️1.3 Code visualization

The program for the HC-SR04 ultrasonic sensor was developed and visualized in the Arduino IDE environment using the SEEED STUDIO XIAO RP2040 microcontroller. The code defines the TRIG and ECHO pins, initializes serial communication, and continuously measures the distance detected by the ultrasonic sensor. During execution, the microcontroller sends a short trigger pulse to the sensor, receives the echo signal, and calculates the distance based on the ultrasonic wave travel time. The measured values are then displayed in the Serial Monitor, allowing real-time visualization of the sensor data. This programming process helped me understand how input devices communicate with microcontrollers through digital signals and how sensor data can be processed and monitored using embedded programming tools.

Programming Process: HC-SR04 Ultrasonic Sensor (Arduino IDE)

1.4.1 Define Pins

#define TRIG_PIN D1
#define ECHO_PIN D0

- TRIG_PIN: Used to send the ultrasonic pulse signal.
- ECHO_PIN: Used to receive the reflected signal from the object.

1.4.2 Setup Configuration

void setup() {
  Serial.begin(115200);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
}

- Serial.begin(115200): Initializes serial communication.
- pinMode: Configures TRIG as output and ECHO as input.

1.4.3 Generate Ultrasonic Pulse

digitalWrite(TRIG_PIN, LOW);
delayMicroseconds(5);

digitalWrite(TRIG_PIN, HIGH);
delayMicroseconds(10);
digitalWrite(TRIG_PIN, LOW);

- Sends a short pulse (10 microseconds) to trigger the ultrasonic sensor.

1.4.4 Read Echo Signal

duration = pulseIn(ECHO_PIN, HIGH, 30000);

- pulseIn(): Measures the time the signal stays HIGH.
- Timeout is set to avoid blocking if no signal is received.

1.4.5 Calculate Distance

if (duration == 0) {
  Serial.println(0);
} else {
  distance = (duration * 0.0343) / 2;
  Serial.println(distance);
}

- Converts time into distance using the speed of sound.
- Divided by 2 because the signal travels to the object and back.

1.4.6 Loop Execution

delay(100);

- Adds a small delay between measurements for stability.

✅1.4.7 Program Objective

Measure the distance between the sensor and an object using ultrasonic waves, and display the result in real time through the Serial Monitor.

⚙️1.5 HC-SR04 Ultrasonic Sensor

The HC-SR04 Ultrasonic Sensor is a sensor used to measure distance without contact using ultrasonic waves. It sends a sound wave and calculates the distance based on the time it takes to bounce back from an object. Key specifications: operates at 5V, measures from 2 cm to 4 m, has an accuracy of ±3 mm, and uses a 40 kHz frequency. It has 4 pins: VCC, GND, TRIG (signal output), and ECHO (signal input).

⚙️1.6 I tasted in PCB

After validating the circuit through simulation, I proceeded to test the system using my custom PCB based on the SEEED STUDIO XIAO RP2040. The HC-SR04 ultrasonic sensor and the humidity and temperature sensor were connected directly to the board to verify real hardware communication and sensor functionality. Using the Arduino IDE and Serial Monitor, I was able to observe the sensor readings in real time, confirming that the PCB connections, power distribution, and signal communication were working correctly. This stage allowed me to validate the transition from simulation to physical implementation while also testing the reliability of the PCB design and the interaction between the microcontroller and the input devices.

⚙️2. Programming Process: DHT11 temperature and humidity sensor(Arduino IDE)

⚙️2.1 I made a Simple Scetch

Before designing the final electronic connections, I created a simple sketch to organize the general structure of the system and visualize how the components would interact with each other. In this sketch, I identified the SEEED STUDIO XIAO RP2040 as the central microcontroller and mapped the connections for the DHT11 temperature and humidity sensor. This preliminary drawing helped me understand the required input pins, power connections, and signal flow between the sensor and the PCB. Additionally, the sketch served as an initial planning step before moving to the simulation and programming stages, making the development process more organized and easier to understand.

📈2.2 Simulation of the circuit:

Before implementing the physical hardware, I simulated the circuit in the Wokwi platform using the DHT11 temperature and humidity sensor connected to the SEEED STUDIO XIAO RP2040 microcontroller. This simulation allowed me to verify the communication between the sensor and the microcontroller while testing the Arduino code in a virtual environment. Through the Serial Monitor available in Wokwi, I was able to visualize the temperature and humidity readings in real time, confirming that the sensor data was being processed correctly. This stage helped me validate the wiring connections, the sensor library configuration, and the logic of the embedded program before testing the circuit on the physical PCB. Additionally, the simulation improved my understanding of how digital environmental sensors communicate with microcontrollers and transmit data for monitoring and analysis applications.

⚙️2.3 Code visualization

The program for the DHT11 temperature and humidity sensor was developed and visualized in the Arduino IDE using the SEEED STUDIO XIAO RP2040 microcontroller. The code initializes the DHT11 sensor library, configures the communication pin, and continuously reads the environmental data generated by the sensor. During execution, the microcontroller processes both the temperature and humidity values and sends the information to the Serial Monitor for real-time visualization. This programming stage helped me understand how digital sensors communicate with embedded systems and how environmental data can be acquired, processed, and monitored through Arduino-based programming.

Programming Process: DHT11 Temperature & Humidity Sensor (Arduino IDE)

2.4.1 Import Required Library

#include "DHT.h"

- DHT library: Used to interface with the DHT11 sensor and read temperature and humidity values.

2.4.2 Define Sensor Type and Pin

#define DHTPIN D2
#define DHTTYPE DHT11

DHT dht(DHTPIN, DHTTYPE);

- DHTPIN: Digital pin where the sensor is connected.
- DHTTYPE: Specifies the sensor model (DHT11).
- DHT object: Initializes the sensor.

2.4.3 Setup Configuration

void setup() {
  Serial.begin(115200);
  dht.begin();
}

- Serial.begin(115200): Starts serial communication.
- dht.begin(): Initializes the sensor.

2.4.4 Read Sensor Data

float temperature = dht.readTemperature();
float humidity = dht.readHumidity();

- Reads temperature in Celsius and humidity percentage from the sensor.

2.4.5 Validate and Display Data

if (isnan(temperature) || isnan(humidity)) {
  Serial.println("Error reading from DHT11");
} else {
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" °C");

  Serial.print("Humidity: ");
  Serial.print(humidity);
  Serial.println(" %");
}

- isnan(): Checks if the reading failed.
- If valid, the data is printed to the Serial Monitor.

2.4.6 Loop Delay

delay(2000);

- The DHT11 sensor requires a delay between readings (minimum 1–2 seconds).

✅ 2.4.7 Program Objective

Measure environmental temperature and humidity using the DHT11 sensor and display the values in real time through the Serial Monitor. This allows monitoring environmental conditions for further analysis.

3. I tasted in PCB

In this stage, I tested the DHT11 temperature and humidity sensor directly on the fabricated PCB using the XIAO ESP32 S3 as the main microcontroller. After connecting the sensor to the corresponding power, ground, and data pin, I uploaded the program to read temperature and humidity values.

I monitored the output through the Serial Monitor, where I was able to observe real-time environmental data. This allowed me to verify that the sensor was correctly connected and communicating properly with the microcontroller.