IoT-Based Smart Home Controller Using Blynk

The IoT-Based Smart Home Controller Using Blynk is built around the NodeMCU ESP8266 microcontroller, which acts as the central processing unit and connects to a local Wi-Fi network to communicate with the cloud. Power is supplied by a 12V battery, stepped down via a 5V regulator (IC1) to safely power the logic circuitry and sensors, while higher-power components utilize the 12V rail. The system integrates multiple sensors to continuously gather environmental data: a DHT11 sensor measures ambient temperature and humidity, a 5V DC soil moisture sensor evaluates ground conditions, and an HC-SR04 ultrasonic sensor uses high-frequency sound waves to measure liquid or spatial distances for water level monitoring. This telemetry is processed by the ESP8266 and transmitted wirelessly to the Blynk Mobile App running on an Android device, allowing users to view real-time metrics remotely. Conversely, users can send commands from the mobile app to trigger automated actions. The microcontroller outputs control signals to drive four 12V single-changeover relays (RL1 through RL4). These electromechanical switches act as isolated barriers, enabling the low-voltage digital pins of the NodeMCU to safely control higher-current electrical loads, specifically two light bulbs designated as Load2 and Load3, as well as other connected devices.