Build a smart thermal monitor

Node-RED is a powerful programming language that requires no code to be written – rather we connect nodes containing functions together to perform a task. When used with MQTT (Message Query Telemetry Transport–a lightweight protocol to send and receive data) we can create applications that can talk across the world. In this tutorial we’ll build an Internet of Things temperature probe with built-in OLED screen. All powered by a Raspberry Pi.

The DHT22 sensor is an affordable and simple sensor to work with and works well for breadboard use. It requires a 10K Ohm resistor between 3V and pin 2 (data), which ensures that the data pin is always pulled up. The OLED screen