NeoPixelとは
WS2812 LED stripだ
結線
電源の他に、DataはP0につなぐ。
コード
コードは参考１から利用
https://github.com/smartynov/iotfun/tree/master/arduino/deco_lights
WS2812は8個内蔵だから、下記のように変更する
#define PIN 0
#define NUMPIXELS 8
また64個内蔵の場合、BRIGHTNESS を弱めて、下記のように変更する。
#include <Adafruit_NeoPixel.h>
// set to pin connected to data input of WS8212 (NeoPixel) strip
#define PINGND 0
#define PIN 1
#define PINVCC 2
// any pin with analog input (used to initialize random number generator)
#define RNDPIN 2
// number of LEDs (NeoPixels) in your strip
// (please note that you need 3 bytes of RAM available for each pixel)
#define NUMPIXELS 64
// max LED brightness (1 to 255) – start with low values!
// (please note that high brightness requires a LOT of power)
#define BRIGHTNESS 32
// increase to get narrow spots, decrease to get wider spots
#define FOCUS 65
// decrease to speed up, increase to slow down (it's not a delay actually)
#define DELAY 4000
// set to 1 to display FPS rate
#define DEBUG 0
Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);
// we have 3 color spots (reg, green, blue) oscillating along the strip with different speeds
float spdr, spdg, spdb;
float offset;
#if DEBUG
// track fps rate
long nextms = 0;
int pfps = 0, fps = 0;
#endif
// the real exponent function is too slow, so I created an approximation (only for x < 0)
float myexp(float x) {
return (1.0/(1.0-(0.634-1.344*x)*x));
}
void setup() {
pinMode(PINVCC, OUTPUT);
digitalWrite(PINVCC, HIGH);
pinMode(PINGND, OUTPUT);
digitalWrite(PINGND, LOW);
// initialize pseudo-random number generator with some random value
randomSeed(analogRead(RNDPIN));
// assign random speed to each spot
spdr = 1.0 + random(200) / 100.0;
spdg = 1.0 + random(200) / 100.0;
spdb = 1.0 + random(200) / 100.0;
// set random offset so spots start in random locations
offset = random(10000) / 100.0;
// initialize LED strip
strip.begin();
strip.show();
}
void loop() {
// use real time to recalculate position of each color spot
long ms = millis();
// scale time to float value
float m = offset + (float)ms/DELAY;
// add some non-linearity
m = m - 42.5*cos(m/552.0) - 6.5*cos(m/142.0);
// recalculate position of each spot (measured on a scale of 0 to 1)
float posr = 0.5 + 0.55*sin(m*spdr);
float posg = 0.5 + 0.55*sin(m*spdg);
float posb = 0.5 + 0.55*sin(m*spdb);
// now iterate over each pixel and calculate it's color
for (int i=0; i<NUMPIXELS; i++) {
// pixel position on a scale from 0.0 to 1.0
float ppos = (float)i / NUMPIXELS;
// distance from this pixel to the center of each color spot
float dr = ppos-posr;
float dg = ppos-posg;
float db = ppos-posb;
// set each color component from 0 to max BRIGHTNESS, according to Gaussian distribution
strip.setPixelColor(i,
constrain(BRIGHTNESS*myexp(-FOCUS*dr*dr),0,BRIGHTNESS),
constrain(BRIGHTNESS*myexp(-FOCUS*dg*dg),0,BRIGHTNESS),
constrain(BRIGHTNESS*myexp(-FOCUS*db*db),0,BRIGHTNESS)
);
}
#if DEBUG
// keep track of FPS rate
fps++;
if (ms>nextms) {
// 1 second passed – reset counter
nextms = ms + 1000;
pfps = fps;
fps = 0;
}
// show FPS rate by setting one pixel to white
strip.setPixelColor(pfps,BRIGHTNESS,BRIGHTNESS,BRIGHTNESS);
#endif
// send data to LED strip
strip.show();
}
参考
- https://www.instructables.com/id/USB-NeoPixel-Deco-Lights-via-Digispark-ATtiny85/
