LEDs, LEDs and more LEDs

After last week’s meeting I went home and started researching LED strips and settled on buying the a strip on Ebay  “RGB LED Pixels 50pc 12mm Diffused 5V Waterproof Addressable Full Color”. I believed it was using the WS2801 chipset such as those sold on Adafruit, but it turns out they are based on the SM16716 chipset which has similar features but functions differently. The LEDs arrived last night and Tyler and I quickly got down to working on them, scavenging an old Mac G4 from an Ewaste bin on campus, and using that as a 5 Volt power supply to power the strip. To do this, you have to cut some of the connectors, and wire the green wire to ground (any given black wire). The green wire allows the power supply to start up. The red wire provides 5 volts which is actually what we needed. Once the power supply was setup, we breadboarded the circuit and downloaded the Fastspi library for Arduino. Currently the strip is not behaving as expected, flickering white and only sometimes animating, and we’re not sure if the wiring is wrong since we are using cheap Ebay lights, or if it is an issue on the code side, since a lot of these libraries are hacked together. More research will be done to get these lights working. Once the lights are operational we will work to create some functions that others can call for animating the lights. Also we hope to hook up buttons and other sensors to make our demos interactive. More updates to come soon!

Update: After looking at more code online I discovered some that works great with the LED strip. Mike Tsao wrote a simple example sans hardware spi  that can be found here.  Linked below is a simple demo using his code:

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