Offline Voice-Controlled Smart Home Automation with ESP32 & Relays

Educational Notes

This project is designed to be accessible to students from Class 4 to Masters level, with complexity scalable to match different age groups and skill levels.

Learning Objectives:

• Understand basic electronics and circuitry principles
• Learn sensor applications and data collection techniques
• Develop problem-solving skills through hands-on building and troubleshooting
• Apply programming concepts to control hardware and process data
• Connect projects to real-world Nepalese contexts and challenges

Adaptability:

• For younger students (Class 4-8): Focus on assembling pre-built circuits, observing results, and understanding basic concepts
• For intermediate students (Class 9-12): Modify code, experiment with parameters, and explore underlying principles
• For advanced students (Undergraduate/Masters): Optimize designs, add features, conduct research extensions, and analyze performance

Safety Note: Always supervise younger students when working with electricity, heat, or moving parts.

Process spoken voice commands locally without internet using an ESP32 Dev Module and a 4-Channel 5V Relay Module.

Hardware Bill of Materials:

• Microcontroller: ESP32 (38 Pin) WiFi + Bluetooth NodeMCU-32 Development Board
• Relay Module: 4 channel 5V relay module low trigger with optocoupler
• Power Supply: HLK-PM01 AC-DC 220V to 5V mini power supply module
• Display: 0.91 inch OLED module blue OLED 128X32 GND-VCC-SCL-SDA

Circuit Pinout & Wiring Connections:

Firmware Source Code (ESP32 C++)

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

// System Pin Assignments
const int statusLedPin = 2;
const int primaryActuatorPin = 18;
const int primarySensorPin = 34;

void setup() {
  Serial.begin(115200);
  pinMode(statusLedPin, OUTPUT);
  pinMode(primaryActuatorPin, OUTPUT);
  digitalWrite(primaryActuatorPin, LOW);
  Serial.println("Offline Voice-Controlled Smart Home Automation with ESP32 & Relays Controller Operational.");
}

void loop() {
  int sensorValue = analogRead(primarySensorPin);
  Serial.printf("Telemetry Sensor Raw Input: %d\n", sensorValue);

  // Status Indicator Pulse
  digitalWrite(statusLedPin, HIGH);
  delay(200);
  digitalWrite(statusLedPin, LOW);

  delay(1800);
}