Cat Litter Odour Motion Detector

Features

Motion detection
Air Quality Sensing
MQTT Support - For Home Assistant
OTA Updates - For easily remotely uploading firmware

Hardware required

NodeMCU ESP8266 (you can use whatever version as long as it has an analogue pin for the odour sensor since it uses varying voltage levels depending on the air quality)
Air Quality Sensor (MQ135)
Mini PIR Motion Sensor (AM312)

Prerequisites

Visual Studio Code (with Platform.IO plugin)
USB to MicroUSB cable - for uploading the firmware and debug/monitoring