In the microcontroller era today, Arduino ... light level is below a threshold value. Here an LDR (Light Dependent Resistor) is used to measure the light level. The alarm system is triggered when a ...

As found in the schematic of the generic PIR motion detector module, one pin of the LDR goes ... and Arduino IDE compatibility. The code is an Arduino project for the Digispark Attiny85 to turn on a ...