Smart Thermostat using ESP8266 & Blynk IoT:

This project is a Wi-Fi enabled smart thermostat built on the ESP8266 NodeMCU microcontroller. It monitors real-time temperature and humidity using a DHT11 sensor and displays the readings on a 16x2 I2C LCD screen. The system is remotely monitored and controlled through the Blynk IoT platform via a smartphone app.

Core Functionality:

The DHT11 sensor continuously reads temperature and humidity every second. These values are sent to the Blynk app (virtual pins V0 and V1) and displayed on the LCD in real time. When the temperature exceeds a defined threshold of 40°C, the system triggers an alert both on the LCD ("!! ALERT >40C !!") and through the LED indicator.

Two Operating Modes:

The system supports two distinct modes, switchable from the Blynk app:

Auto Mode (V3 = ON) — The LED is controlled automatically based on temperature. If the temperature rises above 40°C, the LED turns ON as a warning indicator. Once it drops back below the threshold, the LED turns OFF. Manual control is blocked in this mode.

Manual Mode (V3 = OFF) — The user can directly toggle the LED on or off from the Blynk app using the V2 button. The LCD shows "Manual ctrl only" to indicate the active mode. Auto temperature-based control is disabled.

LCD Feedback:

The 16x2 I2C LCD provides on-device visual feedback at all times. During startup, it runs a loading animation. In normal operation it shows live temperature and humidity. When auto mode detects high temperature, it switches to an alert message. Mode changes (auto/manual) are also briefly displayed on the LCD so the user knows the current state without checking the app.

Blynk Cloud Integration:

The device connects to Wi-Fi and communicates with Blynk cloud over port 80. Virtual pins are used as follows:

V0 — Temperature value (gauge/display widget)

V1 — Humidity value (gauge/display widget)

V2 — LED control button (manual toggle)

V3 — Auto mode toggle switch

On reconnection, the device syncs V2 and V3 from the cloud to restore the last known state, ensuring consistent behavior after power loss or network drops.

Components Used:

ESP8266 NodeMCU (Wi-Fi microcontroller)

DHT11 (temperature and humidity sensor)

16x2 LCD with I2C module (address 0x27)

LED with 220Ω current-limiting resistor

Blynk IoT platform (smartphone app + cloud)

To Know more: Refer Documentation "github.com/heyjsx-cloud/Smart-Thermostat/blob/main/SmartThermostat_Documentation.pdf"