For Toffee posted this project using a trinket and a Pi to control one of our Neopixel rings.
OK, so not 100% accurate; a Pi controlled Adafruit Trinket controlled NeoPixel ring
I got the idea from seeing Dave Whale’s serial based Arduino interface with the Pi. The Trinket doesn’t have serial so I had to use something else to talk to it.
Enter I²C; on the Trinket side I’m using the TinyWireS library, on the Pi side I’m calling smBus.writeList() with a list of the bytes I wish to send. You’ll notice in the video there’s an extra breakout in the circuit, this is a bi-directional level converter to allow the 5v Trinket to talk to the 3.3v Pi without releasing any magic smoke.
My aim is to implement the commands in the Neopixel library however at the moment it just calls setPixelColor with the 4 values (LED, Red, Green, Blue) provided by the Pi. I have a special case of LED==0xFF which lights all LEDs the specified colour (a concept I have pinched from David). I have included the code below in it’s current (probably hacky) state.
Featured Adafruit Products!
NeoPixel Ring – 16 x WS2812 5050 RGB LED with Integrated Drivers: Round and round and round they go! 16 ultra bright smart LED NeoPixels are arranged in a circle with 1.75″ (44.5mm) outer diameter. The rings are ‘chainable’ – connect the output pin of one to the input pin of another. Use only one microcontroller pin to control as many as you can chain together! Each LED is addressable as the driver chip is inside the LED. Each one has ~18mA constant current drive so the color will be very consistent even if the voltage varies, and no external choke resistors are required making the design slim. Power the whole thing with 5VDC (4-7V works) and you’re ready to rock. Read more.
Adafruit Trinket – Mini Microcontroller – 5V Logic: Trinket may be small, but do not be fooled by its size! It’s a tiny microcontroller board, built around the Atmel ATtiny85, a little chip with a lot of power. We wanted to design a microcontroller board that was small enough to fit into any project, and low cost enough to use without hesitation. Perfect for when you don’t want to give up your expensive dev-board and you aren’t willing to take apart the project you worked so hard to design. It’s our lowest-cost arduino-IDE programmable board! Read more.
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