Multi-Sensor Data Visualization and Analysis

This project demonstrates how to use the Seeed Studio XIAO ESP32C3 to gather and visualize data from multiple sensors (MCP9808, SHT45, BME680) and a battery voltage measurement using a voltage divider.

Features

• WiFi Connectivity: Connects to a specified WiFi network.
• Web Server: Hosts a web server on port 80 to serve a webpage with sensor data visualization.
• Sensor Data: Reads data from MCP9808 (temperature), SHT45 (temperature and humidity), and BME680 (temperature, humidity, pressure, and gas resistance).
• Battery Voltage Measurement: Reads battery voltage using a voltage divider circuit.
• Calibration Phase: Calibrates BME680 sensor during startup to ensure accurate readings.

Hardware Requirements

• Seeed Studio XIAO ESP32C3
• MCP9808 Temperature Sensor
• SHT45 Temperature and Humidity Sensor
• BME680 Environmental Sensor
• Voltage Divider (100kΩ and 60kΩ resistors)
• Breadboard and jumper wires
• USB Type-C cable

Circuit Diagram

Voltage Divider for Battery Measurement

• Resistor 1: 100kΩ
• Resistor 2: 60kΩ

Connect the resistors in series between the battery positive terminal and ground. Connect the midpoint of the resistors to GPIO3 (A0) on the XIAO ESP32C3.

Battery Positive --- 100kΩ ---+--- 60kΩ --- Ground
                              |
                            GPIO3

Software Setup

Prerequisites

• Arduino IDE with ESP32 support installed.
• Required libraries: WiFi, WebServer, Wire, Adafruit_MCP9808, Adafruit_SHT4x, Adafruit_BME680, ArduinoJson.

Installation

1. Download and Install Libraries: Ensure the following libraries are installed in your Arduino IDE.

   • WiFi
   • WebServer
   • Wire
   • Adafruit_MCP9808
   • Adafruit_SHT4x
   • Adafruit_BME680
   • ArduinoJson

2. Clone or Download the Repository: Download the source code from this repository.

3. Configure WiFi Credentials: Update the ssid and password variables in the code with your WiFi network credentials.

4. Upload the Code: Connect your XIAO ESP32C3 to your computer using a USB Type-C cable and upload the code using the Arduino IDE.

Usage

1. Power the XIAO ESP32C3: Connect the XIAO ESP32C3 to a power source via USB or battery.

2. Access the Web Interface: Once the device is connected to WiFi, it will print the IP address to the Serial Monitor. Open a web browser and navigate to the provided IP address to view the sensor data and battery voltage.

Code Explanation

Calibration Phase

During the setup, the BME680 sensor undergoes a calibration phase to stabilize the readings. This ensures accurate environmental data before normal operation begins.

void calibrateBME680() {
  Serial.println("Calibrating BME680...");

  // Wait for the BME680 to stabilize
  for (int i = 0; i < 10; i++) {
    if (bme680.performReading()) {
      Serial.print("Temperature: ");
      Serial.print(bme680.temperature);
      Serial.print(" °C, Humidity: ");
      Serial.print(bme680.humidity);
      Serial.print(" %, Pressure: ");
      Serial.print(bme680.pressure / 100.0);
      Serial.print(" hPa, Gas: ");
      Serial.print(bme680.gas_resistance / 1000.0);
      Serial.println(" KΩ");
    } else {
      Serial.println("Failed to perform reading :(");
    }
    delay(1000); // Wait 1 second between readings
  }

  Serial.println("BME680 calibration complete.");
}

Battery Voltage Measurement

The battery voltage is measured using a voltage divider circuit connected to GPIO3. The voltage is then used to calculate the battery percentage.

float readBatteryVoltage() {
  const float attenuation = 2.4706;
  int raw = analogRead(3);
  float voltage = (raw / 4095.0) * 3.3 * attenuation;
  return voltage;
}

float calculateBatteryPercentage(float voltage) {
  if (voltage > 4.2) return 100.0;
  if (voltage < 3.0) return 0.0;
  return (voltage - 3.0) / (4.2 - 3.0) * 100.0;
}

License

This project is licensed under the MIT License - see the LICENSE file for details.