Intro to Embedded System with ESP32 [Database]
Hi, I’m back, in this blog I’ll share my experience with inserting BMP280 sensor data into MySQL using PHP.
You can refer to the component required and circuit schematic in my blog about external sensors here.
In this project, I’ll explain how to host a web, set up the database, insert data, and display database content.
— Web Hosting
I’ll use 000webhost for the hosting service because it’s free and already enough to build this project.
First, go to www.000webhost.com then create your account.
After creating an account, click on Create New Site.
Insert your own website name and password then click Create.
That’s all for hosting the website.
— Database
Now, we’ll continue to configure and set up the database.
Click Tools > Database Manager from the manage website dashboard.
After that click on New Database to start creating the database.
Insert your database name, username, and password for access control.
Then click on Manage > PHPMyAdmin.
Click the database we’ve created.
Click SQL.
After that paste this DDL query to the editor.
CREATE TABLE SensorData (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
sensor VARCHAR(30) NOT NULL,
location VARCHAR(30) NOT NULL,
value1 VARCHAR(10),
value2 VARCHAR(10),
value3 VARCHAR(10),
reading_time TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
)
After that click the Go button and it should successfully create the table for our data.
— PHP
In this part, we’ll create a PHP script responsible for receiving requests from ESP32 and inserting the data into MySQL.
Click on File Manager > Upload Files.
Click on public_html.
Create a new post-esp-data.php file and esp-data.php file
After that paste the PHP script to the file and don’t forget to replace the credential with yours.
<?php
/*
Rui Santos
Complete project details at https://RandomNerdTutorials.com/esp32-esp8266-mysql-database-php/
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files.
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
*/
$servername = "localhost";
// REPLACE with your Database name
$dbname = "REPLACE_WITH_YOUR_DATABASE_NAME";
// REPLACE with Database user
$username = "REPLACE_WITH_YOUR_USERNAME";
// REPLACE with Database user password
$password = "REPLACE_WITH_YOUR_PASSWORD";
// Keep this API Key value to be compatible with the ESP32 code provided in the project page.
// If you change this value, the ESP32 sketch needs to match
$api_key_value = "tPmAT5Ab3j7F9";
$api_key= $sensor = $location = $value1 = $value2 = $value3 = "";
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$api_key = test_input($_POST["api_key"]);
if($api_key == $api_key_value) {
$sensor = test_input($_POST["sensor"]);
$location = test_input($_POST["location"]);
$value1 = test_input($_POST["value1"]);
$value2 = test_input($_POST["value2"]);
$value3 = test_input($_POST["value3"]);
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
$sql = "INSERT INTO SensorData (sensor, location, value1, value2, value3)
VALUES ('" . $sensor . "', '" . $location . "', '" . $value1 . "', '" . $value2 . "', '" . $value3 . "')";
if ($conn->query($sql) === TRUE) {
echo "New record created successfully";
}
else {
echo "Error: " . $sql . "<br>" . $conn->error;
}
$conn->close();
}
else {
echo "Wrong API Key provided.";
}
}
else {
echo "No data posted with HTTP POST.";
}
function test_input($data) {
$data = trim($data);
$data = stripslashes($data);
$data = htmlspecialchars($data);
return $data;
}<!DOCTYPE html>
<html><body>
<?php
/*
Rui Santos
Complete project details at https://RandomNerdTutorials.com/esp32-esp8266-mysql-database-php/
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files.
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
*/
$servername = "localhost";
// REPLACE with your Database name
$dbname = "REPLACE_WITH_YOUR_DATABASE_NAME";
// REPLACE with Database user
$username = "REPLACE_WITH_YOUR_USERNAME";
// REPLACE with Database user password
$password = "REPLACE_WITH_YOUR_PASSWORD";
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
$sql = "SELECT id, sensor, location, value1, value2, value3, reading_time FROM SensorData ORDER BY id DESC";
echo '<table cellspacing="5" cellpadding="5">
<tr>
<td>ID</td>
<td>Sensor</td>
<td>Location</td>
<td>Value 1</td>
<td>Value 2</td>
<td>Value 3</td>
<td>Timestamp</td>
</tr>';
if ($result = $conn->query($sql)) {
while ($row = $result->fetch_assoc()) {
$row_id = $row["id"];
$row_sensor = $row["sensor"];
$row_location = $row["location"];
$row_value1 = $row["value1"];
$row_value2 = $row["value2"];
$row_value3 = $row["value3"];
$row_reading_time = $row["reading_time"];
// Uncomment to set timezone to - 1 hour (you can change 1 to any number)
//$row_reading_time = date("Y-m-d H:i:s", strtotime("$row_reading_time - 1 hours"));
// Uncomment to set timezone to + 4 hours (you can change 4 to any number)
//$row_reading_time = date("Y-m-d H:i:s", strtotime("$row_reading_time + 4 hours"));
echo '<tr>
<td>' . $row_id . '</td>
<td>' . $row_sensor . '</td>
<td>' . $row_location . '</td>
<td>' . $row_value1 . '</td>
<td>' . $row_value2 . '</td>
<td>' . $row_value3 . '</td>
<td>' . $row_reading_time . '</td>
</tr>';
}
$result->free();
}
$conn->close();
?>
</table>
</body>
</html>After that let’s set the ESP32 configuration.
— ESP32 Code
/*
Rui Santos
Complete project details at https://RandomNerdTutorials.com/esp32-esp8266-mysql-database-php/
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files.
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
*/
#include <WiFi.h>
#include <WiFiClientSecure.h>
#include <HTTPClient.h>
#include <Wire.h>
#include <Adafruit_BMP280.h>
// Replace with your network credentials
const char* ssid = "yourwifi";
const char* password = "yourpassword";
// REPLACE with your Domain name and URL path or IP address with path
const char* serverName = "yourposturl";
// Keep this API Key value to be compatible with the PHP code provided in the project page.
// If you change the apiKeyValue value, the PHP file /post-esp-data.php also needs to have the same key
String apiKeyValue = "tPmAT5Ab3j7F9";
String sensorName = "BMP280";
String sensorLocation = "Office";
#define SEALEVELPRESSURE_HPA (1013.25)
Adafruit_BMP280 bmp; // I2C
void setup() {
Serial.begin(115200);
WiFi.begin(ssid, password);
Serial.println("Connecting");
while(WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.print("Connected to WiFi network with IP Address: ");
Serial.println(WiFi.localIP());
// (you can also pass in a Wire library object like &Wire2)
bool status = bmp.begin(0x76);
if (!status) {
Serial.println("Could not find a valid BMP280 sensor, check wiring or change I2C address!");
while (1);
}
}
void loop() {
//Check WiFi connection status
if(WiFi.status()== WL_CONNECTED){
WiFiClientSecure *client = new WiFiClientSecure;
client->setInsecure(); //don't use SSL certificate
HTTPClient https;
// Your Domain name with URL path or IP address with path
https.begin(*client, serverName);
// Specify content-type header
https.addHeader("Content-Type", "application/x-www-form-urlencoded");
// Prepare your HTTP POST request data
String httpRequestData = "api_key=" + apiKeyValue + "&sensor=" + sensorName
+ "&location=" + sensorLocation + "&value1=" + String(bmp.readTemperature())
+ "&value2=" + String(bmp.readAltitude(SEALEVELPRESSURE_HPA)) + "&value3=" + String(bmp.readPressure()/100.0F) + "";
Serial.print("httpRequestData: ");
Serial.println(httpRequestData);
// You can comment the httpRequestData variable above
// then, use the httpRequestData variable below (for testing purposes without the BME280 sensor)
//String httpRequestData = "api_key=tPmAT5Ab3j7F9&sensor=BME280&location=Office&value1=24.75&value2=49.54&value3=1005.14";
// Send HTTP POST request
int httpResponseCode = https.POST(httpRequestData);
// If you need an HTTP request with a content type: text/plain
//https.addHeader("Content-Type", "text/plain");
//int httpResponseCode = https.POST("Hello, World!");
// If you need an HTTP request with a content type: application/json, use the following:
//https.addHeader("Content-Type", "application/json");
//int httpResponseCode = https.POST("{\"value1\":\"19\",\"value2\":\"67\",\"value3\":\"78\"}");
if (httpResponseCode>0) {
Serial.print("HTTP Response code: ");
Serial.println(httpResponseCode);
}
else {
Serial.print("Error code: ");
Serial.println(httpResponseCode);
}
// Free resources
https.end();
}
else {
Serial.println("WiFi Disconnected");
}
//Send an HTTP POST request every 30 seconds
delay(3000);
}Finally, after running the code with your own credential, you can view your database through <databasename>.000webhostapp.com/esp-data.php and it’ll update the sensor data according to the delay code(refresh the web to view the update).
Here’s the result of my sensor data.
By following the step above you’ve already finished this simple project about Database with ESP32. Congrats 🎉. This is simply a simple experiment with Databases; you may try more complex circuits and programs.
I hope this blog can be useful for those who are learning and getting started using ESP32. That’s all for this project, stay tuned for the next experiment with ESP32 !!
