ZepMeds Admin

Arduino Uno + ESP8266-01 Cold Chain Monitor

Since the Arduino Uno does not have built-in Wi-Fi, it must be paired with a helper module like the ESP8266-01 to send data to Firebase. This requires programming both boards separately.
Follow the wiring instructions inside the code comments.

Arduino Uno Sketch

This code reads the DHT11 sensor and sends the data to the ESP8266-01 module via a serial connection.


/*
  ZEPMEDS - ARDUINO UNO SENSOR READER
  ====================================
  
  This code reads temperature and humidity data from a DHT11 sensor and sends it
  over the serial port to a connected ESP8266-01 module.

  This sketch goes on the ARDUINO UNO.

  WIRING (Arduino -> Components):
  -------------------------------
  - 5V      -> DHT11 VCC
  - GND     -> DHT11 GND
  - Pin 4   -> DHT11 DATA

  - Pin 2   -> ESP8266-01 RX pin
  - Pin 3   -> ESP8266-01 TX pin
  -------------------------------
*/

#include <SoftwareSerial.h>
#include "DHT.h"

#define DHT_PIN 4
#define DHT_TYPE DHT11

// Use pins 2 and 3 for software serial communication with the ESP8266
SoftwareSerial espSerial(2, 3); // RX, TX

DHT dht(DHT_PIN, DHT_TYPE);

unsigned long lastSendTime = 0;
const long interval = 30000; // Send data every 30 seconds

void setup() {
  Serial.begin(9600); // For debugging on the PC
  espSerial.begin(9600); // For communication with ESP8266
  dht.begin();
  Serial.println("Arduino Uno ready. Reading sensor data...");
}

void loop() {
  unsigned long currentTime = millis();
  if (currentTime - lastSendTime >= interval) {
    lastSendTime = currentTime;

    float h = dht.readHumidity();
    float t = dht.readTemperature();

    if (isnan(h) || isnan(t)) {
      Serial.println("Failed to read from DHT sensor!");
      return;
    }

    // Create a simple comma-separated string to send
    String dataToSend = String(t) + "," + String(h);

    // Send data to ESP8266-01
    espSerial.println(dataToSend);

    // Print to local serial monitor for debugging
    Serial.print("Data sent to ESP8266: ");
    Serial.println(dataToSend);
  }
}