Here, a standard light-dependent resistor (LDR) is used as an analog input sensor and directs its output to the Serial ... After uploading the Arduino code (as usual), just copy/paste the Processing ...

[Gord Payne] has one with an elegant sensor ... reaching the LDR from the LED decreases as the pipe is bent, and with a simple divider circuit a voltage can be read by an Arduino.

In the microcontroller era today, Arduino is ... Here an LDR (Light Dependent Resistor) is used to measure the light level. The alarm system is triggered when a “Logic High (H)” level signal is ...