We (tylercrumpton and hfuller) are on the square downtown at the DayLIT event with the latest LightHSV project. Come see us!
The foam cube wirelessly commands a set of effects when it’s rotated. We used Synapse Wireless’ SNAP Modules, a MPU-6050, an Arduino UNO, and WS2812B LEDs for this project. Check out the code here.
Between rigging up a small LED matrix to my member storage and returning my 3D printer + webcam to the shop, the idea of measuring ambient light has come up several times. Finding a photoresistor to do this turned out to be beyond simple: a member gave me one to use. But once the thought had crossed my mind, I wanted to follow through with this LED sensor thing and see if it’s really up to snuff.
First, gotta find out how it all works. Easy: another shop member wrote a library for it. And the library references an Arduino page which describes the operation: Light Emitting Diodes are typically wired to produce light. But, if you attempt to apply reversed voltage, then the LED will reject current (it is a diode after all) and will do something I find pretty cool: it acts as a tiny capacitor. And even cooler: the capacitor’s characteristics will change based on how much light is reaching the LED’s substrate. So this library will “charge” the LED by applying VCC->VSS backwards on the device, and then measure the length of time it takes for the capacitor to discharge (which is dependent on the ambient light). Neat!