NeoPixel Control Example Explanation (K230)

Overview

This example demonstrates how to control WS2812 (NeoPixel) RGB LEDs on the K230 development board using the neopixel module. With this module, users can flexibly control the color of each individual RGB LED, enabling dynamic lighting effects, smooth color transitions, and pixel-level testing.

NeoPixel (WS2812) LEDs use single-wire serial communication, allowing multiple LEDs to be daisy-chained and controlled simultaneously.

This example includes:

• Setting all pixels to a solid color

• Lighting up LEDs one by one

• Clearing (turning off) all LEDs

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Example Code

import time
from machine import Pin
import neopixel

# === CONFIGURATION ===
NEOPIXEL_PIN = 42     # GPIO pin number (adjust based on your wiring)
NUM_PIXELS   = 10     # Number of WS2812 LEDs

# === INITIALIZE NEOPIXEL OBJECT ===
np = neopixel.NeoPixel(Pin(NEOPIXEL_PIN), NUM_PIXELS)

# === FUNCTION: Show solid colors ===
def test_colors():
    print("[TEST] Setting colors...")
    colors = [(255, 0, 0), (0, 255, 0), (0, 0, 255), (128, 128, 0)]  # Red, Green, Blue, Yellow

    for i, color in enumerate(colors):
        for j in range(NUM_PIXELS):
            np[j] = color
        np.write()
        print(f"  → Color: {color}")
        time.sleep(0.5)

# === FUNCTION: Test individual pixel addressing ===
def test_pixels():
    print("[TEST] Lighting up pixels one by one...")
    for i in range(NUM_PIXELS):
        np.fill((0, 0, 0))         # Clear all pixels
        np[i] = (0, 255, 128)      # Light up pixel i in teal
        np.write()
        print(f"  → Pixel {i} ON")
        time.sleep(0.2)

# === FUNCTION: Clear all pixels ===
def clear():
    np.fill((0, 0, 0))
    np.write()
    print("[TEST] Cleared all pixels.")

# === MAIN TEST SEQUENCE ===
def run_test():
    test_colors()
    test_pixels()
    clear()
    print("[DONE] NeoPixel test completed.")

run_test()

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Code Structure Explained

1. Initialize NeoPixel

np = neopixel.NeoPixel(Pin(42), 10)

• Uses GPIO 42 to control the LED strip

• Configured for 10 LEDs

• Each LED is RGB (default bpp=3)

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2. Set All Pixels to Solid Colors (test_colors)

colors = [(255, 0, 0), (0, 255, 0), (0, 0, 255), (128, 128, 0)]

• Sets all pixels to red, green, blue, and yellow in sequence

• Can use either np.fill() or set each pixel manually

• np.write() sends the data to the LED strip

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3. Light Pixels One by One (test_pixels)

np[i] = (0, 255, 128)

• Lights up one LED at a time, clears the rest

• Useful for verifying pixel order and direction

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4. Clear All Pixels (clear)

np.fill((0, 0, 0)); np.write()

• Turns off all pixels by setting color to black (0, 0, 0)

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Notes & Recommendations

Item	Description
GPIO Selection	Choose an unused GPIO, e.g., GPIO42 or GPIO43
Max Pixels	Due to timing and interrupt constraints, it’s recommended to use ≤ 16 LEDs
Power Supply	Each WS2812 LED can draw up to 60 mA at full brightness; use external power
Performance	Interrupts are disabled during data transmission; limit length/refresh rate

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More Information

For advanced effects like rainbow animations, fading, or brightness control, refer to the MicroPython official documentation: 👉 https://docs.micropython.org/en/latest/library/neopixel.html

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