Sending Data from ESP32 to Google Sheets (IoT Data Logger Tutorial)

Introduction

Logging sensor data to the cloud is one of the most common uses of ESP32. In this tutorial, you’ll learn how to send data from an ESP32 to a Google Sheet in real-time using Google Apps Script and a simple HTTP POST request.

What You’ll Need

• ESP32 Board
• Arduino IDE
• Wi-Fi Network
• Google Account (for Sheets & Script)
• (Optional) Sensor (e.g., DHT11, DHT22, LDR)

Step 1: Create Your Google Sheet

• Go to Google Sheets
• Create a new sheet and name it, e.g., ESP32_Data_Logger
• In Row 1, add headers like:Timestamp, Temperature, Humidity

Step 2: Create a Google Apps Script

In your Google Sheet, click Extensions > Apps Script

Replace the default code with this script:

function doPost(e) {
  var sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  var data = JSON.parse(e.postData.contents);
  sheet.appendRow([new Date(), data.temp, data.hum]);
  return ContentService.createTextOutput("Success");
}

Save the script and name it ESP32 Logger

Click Deploy > New deployment

Select “Web App”, name it, and set:

• Execute as: Me
• Who has access: Anyone

Click Deploy and Authorize the permissions

Copy the Web App URL (you’ll need it for ESP32)

Step 3: ESP32 Arduino Code

1. Replace WiFi Credentials

Find these two lines in your code:

const char* ssid = "Your_WiFi_Name";
const char* password = "Your_WiFi_Password";

Replace "Your_WiFi_Name" and "Your_WiFi_Password" with your actual WiFi network name and password.

2. Replace Google Script URL

Find this line:

const char* scriptURL = "https://script.google.com/macros/s/YOUR_SCRIPT_ID/exec";

Replace the whole URL with your real Web App URL from Google Apps Script:

#include <WiFi.h>
#include <HTTPClient.h>

// Replace with your WiFi and Web App details
const char* ssid = "Your_WiFi_Name";
const char* password = "Your_WiFi_Password";
const char* scriptURL = "https://script.google.com/macros/s/YOUR_SCRIPT_ID/exec";

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting...");
  }
  Serial.println("Connected to WiFi");
}

void loop() {
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;

    http.begin(scriptURL);
    http.addHeader("Content-Type", "application/json");

    // Replace with your sensor data
    float temp = random(20, 30);  // Simulated temperature
    float hum = random(40, 60);   // Simulated humidity

    String jsonData = "{\"temp\": " + String(temp) + ", \"hum\": " + String(hum) + "}";

    int httpResponseCode = http.POST(jsonData);

    Serial.println("Response code: " + String(httpResponseCode));
    http.end();
  } else {
    Serial.println("WiFi Disconnected");
  }

  delay(10000); // Send data every 10 seconds
}

Expected Output

• Your ESP32 will connect to WiFi.
• Every 10 seconds, it sends temperature & humidity data.
• Google Sheet automatically updates with a timestamp.

Security Tips

• Use HTTPS in the script URL.
• Restrict access using Google Apps Script token/authentication (for advanced users).
• Avoid hardcoding Wi-Fi passwords in production.

Why Use Google Sheets?

• Free & cloud-based
• Easy to visualize and export data
• Accessible from any device

Wrap Up

You’ve successfully built a basic IoT data logger using ESP32 and Google Sheets. You can now expand this by:

• Logging real sensor data (DHT11, MQ2, etc.)
• Adding charts in Sheets
• Automating email alerts when thresholds are crossed.