#include <WiFi.h>
#include <PubSubClient.h>
WiFiClient espClient;
PubSubClient client(espClient);
void setup() { Serial.begin(115200); connectWiFi(); client.setServer(mqtt_server, 1883); }
void loop() {
float co2 = readCO2();
client.publish("airq/sensor1", String(co2).c_str());
delay(5000);
}
const express = require('express');
const { Pool } = require('pg');
const app = express();
const pool = new Pool({connectionString: process.env.DATABASE_URL});
app.get('/api/measurements', async (req, res) => {
const result = await pool.query('SELECT * FROM measurements ORDER BY timestamp DESC LIMIT 100');
res.json(result.rows);
});
app.listen(3000, () => console.log('Server running on port 3000'));
import { useEffect, useState } from 'react';
import { Line } from 'react-chartjs-2';
function AirQualityChart() {
const [data, setData] = useState([]);
useEffect(() => {
fetch('/api/measurements').then(res => res.json()).then(setData);
}, []);
const chartData = {
labels: data.map(d => new Date(d.timestamp).toLocaleTimeString()),
datasets: [{ label: 'PM2.5', data: data.map(d => d.pm25), borderColor: 'red' }]
};
return <Line data={chartData} />;
}
