Using a small embedded device (Arduino) with a motion sensor, provide notifications of a graffiti tagging events. The device is intended to be placed within sensor distance of a wall or building that is chronically tagged by graffiti "artists" (if the wall is newly cleaned or purposefully painted white it would be called a "honey pot"), and left unattended for months to record when illegal activity occurs.
What You Will Learn - Step By Step
Create a basic 9V battery powered circuit, using a PIR (Passive Infra-Red) sensor, to detect when a person crosses the field of view of the sensor. Initially, only the sensor's on-board LED (Light Emitting Diode) will illuminate when the sensor detects a person.
Augment the above circuit with a FET (Field Effect Transistor) and RC (resistance-capacitance) + diode network to turn on another LED for a time period set by the RC network. The LED is meant to simulate turning on the microprocessor (next step), so when a person is detected the LED should stay on for 5 seconds or so even if the person moves out of range.
Use the above circuit to power up an Arduino UNO or Arduino Nano microcontroller board. The Arduino will need to be programmed to Blink when powered up. This involves setting up a development environment like Arduino IDE or using the web based Arduino Create software and a USB cable.
Modify the circuit and program above to add a "sense" function, using an input pin to the Arduino and another FET, to detect when the sensor no longer detects motion, which allows the Arduino to finished processing before it is turned off.
Add a LoRaWan radio device or "hat" and modify the sketch to notify a central location about events in near real-time.
Add non-volatile storage (SDCard) and modify the Arduino sketch to allow the duration (and time&date if available) of the detected motion event to be stored for later analysis.
Add an output circuit and modify the Arduino sketch to take a picture by connecting it to the headphone jack of a cell phone.