Neopixel – WS2812B
Het aansturen van leds is populair. Een RGB led bestaat uit 3 leds, een rode, een groen en een blauwe. Door deze 3 basiskleuren te mengen kan je alle verschillende kleuren maken.
WS2812B leds (door Adafruit ook Neopixel genoemd) zijn smart-RGB leds met een ingebouwde processor aan boord. Door de juiste stroom van bitjes naar de Din pin van deze led te sturen kan je de intensiteit van de 3 kleuren in deze led bepalen.
Meerdere WS2812B leds kunnen in serie geplaatst worden. Elke led heeft 3 bytes van 8 bits (samen 24 bits) nodig om de 3kleuren in die led aan te sturen. De intensiteit van elke basiskleur kan bepaald worden met een 8 bit getal. Dat geeft voor elke basiskleur 255 verschillende intensiteiten en samen geeft dat 255x255x255 (=16.581.375) verschillende kleurcombinaties.
De 4e byte die wordt doorgestuurd is de eerste byte van de volgende led.
Aansluiting Neopixel
De strip met 8 Neopixel leds werkt perfect als die aangesloten is zoals in het schema hierboven.
Deze leds trekken nogal wat stroom. Als je meer dan 8 Neopixel leds op de processor aansluit is het aangeraden om onderstaande aanpassingen te doen.
// NEOPIXEL BEST PRACTICES for most reliable operation:
// – Add 1000 uF CAPACITOR between NeoPixel strip’s + and – connections.
// – MINIMIZE WIRING LENGTH between microcontroller board and first pixel.
// – NeoPixel strip’s DATA-IN should pass through a 300-500 OHM RESISTOR.
// – AVOID connecting NeoPixels on a LIVE CIRCUIT. If you must, ALWAYS
// connect GROUND (-) first, then +, then data.
// – When using a 3.3V microcontroller with a 5V-powered NeoPixel strip,
// a LOGIC-LEVEL CONVERTER on the data line is STRONGLY RECOMMENDED.
// (Skipping these may work OK on your workbench but can fail in the field)
Demo code Neopixel
Voor deze Neopixel zijn er 2 demoprogramma’s.
Het eerste programma demonstreert mooi hoe je één voor één de kleur van de 8 leds bepaald en daarna alles in 1 keer doorstuurt naar de leds.
Het tweede programma demonstreert heel wat verschillende kleureffecten die met deze neopixel-leds te maken zijn.
Adafruit Neopixel lib installeren
Schets >> Bibliotheken gebruiken >> Bibliotheken beheren…
typ “Neopixel” in het venster rechts boven
installeer de Adafruit Neopixel lib
/* NeoPixel LEDs basis BBiot - Jan 2022 - E2CRE8.be - www.stemzone.be installeer eerste de Adafruit Neopixel lib */ #include <Adafruit_NeoPixel.h> #define PIN 6 #define NUMPIXELS 8 Adafruit_NeoPixel pixels(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800); #define DELAYVAL 500 // Time (in milliseconds) to pause between pixels void setup() { pixels.begin(); } void loop() { pixels.clear(); pixels.setBrightness(20); pixels.setPixelColor(0, pixels.Color(255, 255, 255)); // waarden voor led 0 (WIT) pixels.setPixelColor(1, pixels.Color(255, 0, 0)); // waarden voor led 1 (ROOD) pixels.setPixelColor(2, pixels.Color(0, 255, 0)); // waarden voor led 2 (GROEN) pixels.setPixelColor(3, pixels.Color(0, 0, 255)); // waarden voor led 3 (BLAUW) pixels.setPixelColor(4, pixels.Color(255, 0, 255)); pixels.setPixelColor(5, pixels.Color(255, 255, 0)); pixels.setPixelColor(6, pixels.Color(0, 255, 255)); pixels.setPixelColor(7, pixels.Color(0, 100, 100)); pixels.show(); }
/* NeoPixel LEDs uitbreiding BBiot - Jan 2022 - E2CRE8.be - www.stemzone.be installeer eerste de Adafruit Neopixel lib */ // NEOPIXEL BEST PRACTICES for most reliable operation: // - Add 1000 uF CAPACITOR between NeoPixel strip's + and - connections. // - MINIMIZE WIRING LENGTH between microcontroller board and first pixel. // - NeoPixel strip's DATA-IN should pass through a 300-500 OHM RESISTOR. // - AVOID connecting NeoPixels on a LIVE CIRCUIT. If you must, ALWAYS // connect GROUND (-) first, then +, then data. // - When using a 3.3V microcontroller with a 5V-powered NeoPixel strip, // a LOGIC-LEVEL CONVERTER on the data line is STRONGLY RECOMMENDED. // (Skipping these may work OK on your workbench but can fail in the field) #include <Adafruit_NeoPixel.h> // Which pin on the Arduino is connected to the NeoPixels? // On a Trinket or Gemma we suggest changing this to 1: #define LED_PIN 6 // How many NeoPixels are attached to the Arduino? #define LED_COUNT 8 // Declare our NeoPixel strip object: Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800); // Argument 1 = Number of pixels in NeoPixel strip // Argument 2 = Arduino pin number (most are valid) // Argument 3 = Pixel type flags, add together as needed: // NEO_KHZ800 800 KHz bitstream (most NeoPixel products w/WS2812 LEDs) // NEO_KHZ400 400 KHz (classic 'v1' (not v2) FLORA pixels, WS2811 drivers) // NEO_GRB Pixels are wired for GRB bitstream (most NeoPixel products) // NEO_RGB Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2) // NEO_RGBW Pixels are wired for RGBW bitstream (NeoPixel RGBW products) // setup() function -- runs once at startup -------------------------------- void setup() { // These lines are specifically to support the Adafruit Trinket 5V 16 MHz. // Any other board, you can remove this part (but no harm leaving it): #if defined(__AVR_ATtiny85__) && (F_CPU == 16000000) clock_prescale_set(clock_div_1); #endif // END of Trinket-specific code. strip.begin(); // INITIALIZE NeoPixel strip object (REQUIRED) strip.show(); // Turn OFF all pixels ASAP strip.setBrightness(50); // Set BRIGHTNESS to about 1/5 (max = 255) } // loop() function -- runs repeatedly as long as board is on --------------- void loop() { // Fill along the length of the strip in various colors... colorWipe(strip.Color(255, 0, 0), 50); // Red colorWipe(strip.Color( 0, 255, 0), 50); // Green colorWipe(strip.Color( 0, 0, 255), 50); // Blue // Do a theater marquee effect in various colors... theaterChase(strip.Color(127, 127, 127), 50); // White, half brightness theaterChase(strip.Color(127, 0, 0), 50); // Red, half brightness theaterChase(strip.Color( 0, 0, 127), 50); // Blue, half brightness rainbow(10); // Flowing rainbow cycle along the whole strip theaterChaseRainbow(50); // Rainbow-enhanced theaterChase variant } // Some functions of our own for creating animated effects ----------------- // Fill strip pixels one after another with a color. Strip is NOT cleared // first; anything there will be covered pixel by pixel. Pass in color // (as a single 'packed' 32-bit value, which you can get by calling // strip.Color(red, green, blue) as shown in the loop() function above), // and a delay time (in milliseconds) between pixels. void colorWipe(uint32_t color, int wait) { for(int i=0; i<strip.numPixels(); i++) { // For each pixel in strip... strip.setPixelColor(i, color); // Set pixel's color (in RAM) strip.show(); // Update strip to match delay(wait); // Pause for a moment } } // Theater-marquee-style chasing lights. Pass in a color (32-bit value, // a la strip.Color(r,g,b) as mentioned above), and a delay time (in ms) // between frames. void theaterChase(uint32_t color, int wait) { for(int a=0; a<10; a++) { // Repeat 10 times... for(int b=0; b<3; b++) { // 'b' counts from 0 to 2... strip.clear(); // Set all pixels in RAM to 0 (off) // 'c' counts up from 'b' to end of strip in steps of 3... for(int c=b; c<strip.numPixels(); c += 3) { strip.setPixelColor(c, color); // Set pixel 'c' to value 'color' } strip.show(); // Update strip with new contents delay(wait); // Pause for a moment } } } // Rainbow cycle along whole strip. Pass delay time (in ms) between frames. void rainbow(int wait) { // Hue of first pixel runs 5 complete loops through the color wheel. // Color wheel has a range of 65536 but it's OK if we roll over, so // just count from 0 to 5*65536. Adding 256 to firstPixelHue each time // means we'll make 5*65536/256 = 1280 passes through this loop: for(long firstPixelHue = 0; firstPixelHue < 5*65536; firstPixelHue += 256) { // strip.rainbow() can take a single argument (first pixel hue) or // optionally a few extras: number of rainbow repetitions (default 1), // saturation and value (brightness) (both 0-255, similar to the // ColorHSV() function, default 255), and a true/false flag for whether // to apply gamma correction to provide 'truer' colors (default true). strip.rainbow(firstPixelHue); // Above line is equivalent to: // strip.rainbow(firstPixelHue, 1, 255, 255, true); strip.show(); // Update strip with new contents delay(wait); // Pause for a moment } } // Rainbow-enhanced theater marquee. Pass delay time (in ms) between frames. void theaterChaseRainbow(int wait) { int firstPixelHue = 0; // First pixel starts at red (hue 0) for(int a=0; a<30; a++) { // Repeat 30 times... for(int b=0; b<3; b++) { // 'b' counts from 0 to 2... strip.clear(); // Set all pixels in RAM to 0 (off) // 'c' counts up from 'b' to end of strip in increments of 3... for(int c=b; c<strip.numPixels(); c += 3) { // hue of pixel 'c' is offset by an amount to make one full // revolution of the color wheel (range 65536) along the length // of the strip (strip.numPixels() steps): int hue = firstPixelHue + c * 65536L / strip.numPixels(); uint32_t color = strip.gamma32(strip.ColorHSV(hue)); // hue -> RGB strip.setPixelColor(c, color); // Set pixel 'c' to value 'color' } strip.show(); // Update strip with new contents delay(wait); // Pause for a moment firstPixelHue += 65536 / 90; // One cycle of color wheel over 90 frames } } }