Documentation

// WS2812 16-LED Ring - Arduino Example
// DI->D6 via 330 ohm, 5V->5V, GND->GND
// Library: "Adafruit NeoPixel"

#include <Adafruit_NeoPixel.h>

#define PIN      6
#define NUM      16

Adafruit_NeoPixel ring(NUM, PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  ring.begin();
  ring.setBrightness(60);
  ring.show();
}

void spinner(uint32_t color, int loops) {
  for (int t = 0; t < loops * NUM; t++) {
    ring.clear();
    ring.setPixelColor(t % NUM, color);
    ring.setPixelColor((t + 1) % NUM, color);        // 2-px head
    ring.setPixelColor((t + NUM - 1) % NUM,
                       ring.Color(10, 10, 30));      // faint tail
    ring.show();
    delay(60);
  }
}

void gauge(int percent) {                            // 0-100
  int lit = map(percent, 0, 100, 0, NUM);
  ring.clear();
  for (int i = 0; i < lit; i++) {
    // green -> yellow -> red as the gauge fills
    uint8_t r = map(i, 0, NUM - 1, 0, 255);
    uint8_t g = map(i, 0, NUM - 1, 255, 0);
    ring.setPixelColor(i, r, g, 0);
  }
  ring.show();
}

void loop() {
  spinner(ring.Color(0, 120, 255), 4);

  for (int p = 0; p <= 100; p += 5) {                // gauge sweep
    gauge(p);
    delay(80);
  }
  delay(600);
}

# WS2812 16-LED Ring - ESP32 MicroPython Example
# DI->GPIO 13 via 330 ohm, 5V->VIN, GND->GND

from machine import Pin
import neopixel, time

NUM = 16
ring = neopixel.NeoPixel(Pin(13), NUM)
BRIGHT = 0.25

def scale(c):
    return tuple(int(v * BRIGHT) for v in c)

def spinner(color, loops=4):
    for t in range(loops * NUM):
        ring.fill((0, 0, 0))
        ring[t % NUM] = scale(color)
        ring[(t + 1) % NUM] = scale(color)
        ring[(t - 1) % NUM] = scale((10, 10, 30))
        ring.write()
        time.sleep_ms(60)

def gauge(percent):
    lit = percent * NUM // 100
    ring.fill((0, 0, 0))
    for i in range(lit):
        r = i * 255 // (NUM - 1)
        g = 255 - r
        ring[i] = scale((r, g, 0))
    ring.write()

def breathe(color, cycles=2):
    for _ in range(cycles):
        for lv in list(range(0, 100)) + list(range(100, 0, -1)):
            ring.fill(tuple(int(v * lv / 100 * BRIGHT) for v in color))
            ring.write()
            time.sleep_ms(10)

while True:
    spinner((0, 120, 255))
    for p in range(0, 101, 5):
        gauge(p)
        time.sleep_ms(80)
    breathe((150, 0, 255))

#!/usr/bin/env python3
# WS2812 16-LED Ring - Raspberry Pi Example (rpi_ws281x)
# DI->GPIO18 (pin 12) via 330 ohm; run with sudo
# Install: sudo pip3 install rpi_ws281x

import time
from rpi_ws281x import PixelStrip, Color

NUM = 16
strip = PixelStrip(NUM, 18, brightness=60)
strip.begin()

def clear():
    for i in range(NUM):
        strip.setPixelColor(i, 0)

def spinner(color, loops=4):
    for t in range(loops * NUM):
        clear()
        strip.setPixelColor(t % NUM, color)
        strip.setPixelColor((t + 1) % NUM, color)
        strip.show()
        time.sleep(0.06)

def gauge(percent):
    lit = percent * NUM // 100
    clear()
    for i in range(lit):
        r = i * 255 // (NUM - 1)
        g = 255 - r
        strip.setPixelColor(i, Color(r, g, 0))
    strip.show()

try:
    while True:
        spinner(Color(0, 120, 255))
        for p in range(0, 101, 5):
            gauge(p)
            time.sleep(0.08)
        time.sleep(0.6)
except KeyboardInterrupt:
    clear(); strip.show()
    print("Stopped by user")

# WS2812 16-LED Ring - Pico MicroPython Example
# DI->GP0 via 330 ohm, 5V->VBUS, GND->GND
# Countdown-timer demo: ring empties over N seconds, then flashes.

from machine import Pin
import neopixel, time

NUM = 16
ring = neopixel.NeoPixel(Pin(0), NUM)
BRIGHT = 0.25

def scale(c):
    return tuple(int(v * BRIGHT) for v in c)

def countdown(seconds=16):
    per_led = seconds / NUM
    for lit in range(NUM, 0, -1):
        ring.fill((0, 0, 0))
        for i in range(lit):
            color = (0, 255, 60) if lit > NUM // 4 else (255, 30, 0)
            ring[i] = scale(color)
        ring.write()
        time.sleep(per_led)

def flash(color, times=4):
    for _ in range(times):
        ring.fill(scale(color)); ring.write(); time.sleep_ms(120)
        ring.fill((0, 0, 0));    ring.write(); time.sleep_ms(120)

while True:
    countdown(16)          # 1 LED per second
    flash((255, 0, 0))
    time.sleep(1)