Complete Guide to IoT Development with Raspberry Pi and Node.js

The Internet of Things (IoT) connects the physical and digital worlds, enabling automated data collection and remote hardware actuation across smart buildings, agricultural fields, and industrial plants. The Raspberry Pi represents an exceptional platform for IoT edge computing thanks to its full Linux operating system, low power consumption, and rich General Purpose Input/Output (GPIO) pins.

Required Hardware & Environmental Architecture

To construct a robust IoT telemetry monitoring node, prepare the following components:

• Raspberry Pi 4 Model B (2GB or 4GB RAM) running Raspberry Pi OS Lite.
• Digital Humidity & Temperature Sensor (DHT22): Capable of measuring temperatures from -40°C to 80°C.
• Capacitive Soil Moisture Sensor: Resists galvanic corrosion compared to resistive probes.
• 5V Solid State Relay Module: Safely triggers AC/DC pumps or lighting systems.
• Reliable 5V/3A USB-C Power Supply or solar battery unit for remote field operation.

Reading Sensor Telemetry with Node.js

Using the Linux epoll driver and Node.js hardware libraries, we can read sensor pulses and transmit processed values to central cloud dashboards:

const { Gpio } = require('onoff');

class HardwareController {
  constructor(relayPin = 27) {
    this.relay = new Gpio(relayPin, 'out');
    this.relay.writeSync(0); // Ensure relay is initially open
  }

  setPumpStatus(enable) {
    this.relay.writeSync(enable ? 1 : 0);
    console.log(`Relay status updated: ${enable ? 'ACTIVE' : 'STANDBY'}`);
  }

  cleanup() {
    this.relay.unexport();
  }
}

// Graceful shutdown handling
const controller = new HardwareController();
process.on('SIGINT', () => {
  controller.cleanup();
  process.exit();
});