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ESP32C3-Based Multi-Sensor Data Logger with Wi-Fi and SD Card Storage

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Circuit Documentation

Summary

This circuit is designed to collect data from various sensors including the BME/BMP280, HMC5883L compass, MAX30102, and GPS NEO 6M. The collected data is recorded to an SD card and sent over WiFi using API calls. The circuit is powered by a 3.7V LiPo battery and controlled by an XIAO ESP32C3 microcontroller.

Component List

  1. HMC5883L Compass

    • Description: 3-axis digital magnetometer
    • Pins: DRDY, SDA, SCL, GND, VCC

  2. BME/BMP280

    • Description: Temperature, pressure, and humidity sensor
    • Pins: GND, SCL, SDA, VIN

  3. 3.7V LiPo Battery

    • Description: Rechargeable lithium polymer battery
    • Pins: +Ve, GND

  4. Resistor (4700 Ohms)

    • Description: Resistor with 4700 Ohms resistance
    • Pins: pin1, pin2

  5. MAX30102

    • Description: Pulse oximeter and heart-rate sensor
    • Pins: VIN, SDA, SCL, GND, RD, IRD, INT

  6. GPS NEO 6M

    • Description: GPS module
    • Pins: VCC, RX, TX, GND

  7. SD SDHC

    • Description: SD card module
    • Pins: 3V3, CS, MOSI, CLK, MISO, GND

  8. XIAO ESP32C3

    • Description: Microcontroller with WiFi and Bluetooth capabilities
    • Pins: GPIO2/A0/D0, GPIO3/A1/D1, GPIO4/A2/D2, GPIO5/A3/D3, GPIO6/SDA/D4, GPIO7/SCL/D5, GPIO21/Tx/D6, 5V, GND, 3V3, GPIO10/MOSI/D10, GPIO9/MISO/D9, GPIO8/SCK/D8, GPIO20/Rx/D7

Wiring Details

HMC5883L Compass

BME/BMP280

3.7V LiPo Battery

Resistor (4700 Ohms)

MAX30102

GPS NEO 6M

SD SDHC

XIAO ESP32C3

Documented Code

Code for XIAO ESP32C3

/*
 * This Arduino Sketch collects data from various sensors (BME/BMP280, HMC5883L, 
 * MAX30102, GPS NEO 6M) and records the data to an SD card. Additionally, it 
 * sends the data over WiFi using API calls.
 */

#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <WiFi.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>
#include <Adafruit_HMC5883_U.h>
#include <Adafruit_MAX30105.h>
#include <TinyGPS++.h>

// Pin definitions
#define SD_CS_PIN 10

// Sensor objects
Adafruit_BME280 bme;
Adafruit_HMC5883_Unified mag = Adafruit_HMC5883_Unified(12345);
Adafruit_MAX30105 max30105;
TinyGPSPlus gps;

// WiFi credentials
const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";

// API endpoint
const char* server = "http://your_api_endpoint.com/data";

void setup() {
  Serial.begin(115200);
  Wire.begin();

  // Initialize SD card
  if (!SD.begin(SD_CS_PIN)) {
    Serial.println("SD card initialization failed! Retrying...");
    delay(1000);
    if (!SD.begin(SD_CS_PIN)) {
      Serial.println("SD card initialization failed again. Check connections.");
      return;
    }
  }
  Serial.println("SD card initialized.");

  // Initialize BME280
  if (!bme.begin(0x76)) {
    Serial.println("BME280 initialization failed! Check sensor connections.");
    return;
  }
  Serial.println("BME280 initialized.");

  // Initialize HMC5883L
  if (!mag.begin()) {
    Serial.println("HMC5883L initialization failed! Check sensor connections.");
    return;
  }
  Serial.println("HMC5883L initialized.");

  // Initialize MAX30105
  if (!max30105.begin(Wire, I2C_SPEED_FAST)) {
    Serial.println("MAX30105 initialization failed! Check sensor connections.");
    return;
  }
  Serial.println("MAX30105 initialized.");

  // Initialize GPS
  Serial1.begin(9600, SERIAL_8N1, 20, 21);

  // Connect to WiFi
  WiFi.begin(ssid, password);
  unsigned long startAttemptTime = millis();
  while (WiFi.status() != WL_CONNECTED && millis() - startAttemptTime < 10000) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("Failed to connect to WiFi. Check credentials and network.");
    return;
  }
  Serial.println("Connected to WiFi.");
}

void loop() {
  // Read BME280 data
  float temperature = bme.readTemperature();
  float pressure = bme.readPressure() / 100.0F;
  float humidity = bme.readHumidity();

  // Read HMC5883L data
  sensors_event_t event;
  mag.getEvent(&event);
  float heading = event.magnetic.heading;

  // Read MAX30105 data
  long irValue = max30105.getIR();

  // Read GPS data
  while (Serial1.available() > 0) {
    gps.encode(Serial1.read());
  }
  float latitude = gps.location.lat();
  float longitude = gps.location.lng();

  // Create data string
  String dataString = String(temperature) + "," + String(pressure) + "," + 
                      String(humidity) + "," + String(heading) + "," + 
                      String(irValue) + "," + String(latitude) + "," + 
                      String(longitude);

  // Write data to SD card
  File dataFile = SD.open("