NeoPixel Fully addressable multicolour LED

[David Gamble]

https://www.adafruit.com/product/1938

These are a very good alternative to RGB LED. They are available in many formats including 5mm LED, strips, panels and sticks. They are very cheap, $1 each for a 5mm LED. Any number can be wired in series (often up to 60), require only one pin (cf 3 per RGB LED) and use VCC or Vin so that high current will not damage an ESP6822.

Coding is very simple as shown below.
Any pixel on a string can be addressed simply by pixel number and colour. The progam shows 2 Neopixels, nominally front and tail lights. The front and reverse swap depending on diection of travel and then flash yellow as if waiting.

//Program to demonstrate Neopixels for model trains
//David Gamble Feb 2023

// 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 2 // D4 on board
// How many NeoPixels are attached to the Arduino?
#define LED_COUNT 2

// 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() {
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() {

uint32_t red = strip.Color(0, 150, 0);
uint32_t green = strip.Color(150, 0, 0);
uint32_t blue = strip.Color(0, 0, 150);
uint32_t white = strip.Color(150, 150, 150);
uint32_t yellow = strip.Color(150, 175, 0);
uint32_t magenta = strip.Color(150, 0, 150);
uint32_t cyan = strip.Color(0, 150, 150);
uint32_t off = strip.Color(0, 0, 0);

strip.show();
//Forward – headlight (0) Taillight (1)
strip.setPixelColor(0,white); //white
strip.setPixelColor(1,red); //red
strip.show();
delay(1000);
//Reverse
strip.setPixelColor(1,white); //white
strip.setPixelColor(0,red); //red
strip.show();
delay(1000);
// Wait – flashing
for (int i=0; i<10; i++) {
strip.setPixelColor(1,yellow); //yellow
strip.setPixelColor(0,off); //yellow
strip.show();
delay(200);
strip.setPixelColor(1,off); //off
strip.setPixelColor(0,yellow); //off
strip.show();
delay (200);
}
}

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