id144 / SparkCore-DotStar-Alt

SparkCore-DotStar

A library for manipulating DotStar RGB LEDs for the Spark Core. Implementation based on Adafruit's DotStar Library.

DotStar LED's are APA102: Datasheet

Components Required

• A DotStar digital RGB LED (get at adafruit.com)
• A Spark Shield Shield or breakout board to supply DotStars with 5V (see store at spark.io)

Example Usage

Adafruit_DotStar strip = Adafruit_DotStar(NUMPIXELS, DATAPIN, CLOCKPIN);
void setup() {
  strip.begin();
  strip.show();
}
void loop() {
  // change your pixel colors and call strip.show() again
}

Nuances

• Make sure get the # of pixels, clock and data pin numbers (SW SPI can be any pins, HW SPI can only be A3 (clock) & A5 (data))

• DotStars require 5V logic level inputs and the Spark Core only has 3.3V logic level digital outputs. Level shifting from 3.3V to 5V is necessary, the Spark Shield Shield has the TXB0108PWR 3.3V to 5V level shifter built in (but has been known to oscillate at 50MHz with wire length longer than 6"), alternatively you can wire up your own with a SN74HCT245N, or SN74HCT125N. These are rock solid.

Useful Links

• DotStar Guide: https://learn.adafruit.com/adafruit-dotstar-leds
• Quad Level Shifter IC: SN74ACHT125N (Adafruit)
• Quad Level Shifter IC: SN74HCT125N (Digikey)
• Quad Level Shifter IC: SN74AHCT125N (Digikey)