RGB LED Effects

1. RGB Colorful Light Overview

WS2812 (also known as NeoPixel) is a single-wire addressable RGB LED chip. Each LED has a built-in control IC, and only one data wire is needed to cascade and control hundreds of LEDs. This experiment drives the single onboard WS2812 (GPIO48), cycling through 7 rainbow colors, switching once per second while printing the current color name via serial.

Typical application scenarios:

2. Core Concepts

2.1 WS2812 Communication Protocol

The WS2812 uses a single-wire return-to-zero code: there is only one data wire, and different pulse widths represent 0 and 1.

0 code: ██░░              0.4μs high + 0.85μs low
1 code: ████░░            0.8μs high + 0.45μs low
RESET: ░░░░ > 50μs        low > 50μs = latch signal

Each LED requires 24 bits of data (8 bits each for G-R-B); cascading N LEDs requires 24×N bits. The RESET signal latches the data in the shift register to the output.

2.2 WS2812 Color Format — GRB

The native color order of the WS2812 is GRB (Green-Red-Blue), which differs from the common RGB order:

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#                  G    R    B
RAINBOW = [
    (150, 0,   0),   # red:   G=0,   R=150, B=0
    (0,   150, 0),   # green: G=150, R=0,   B=0
    (0,   0,   150), # blue:  G=0,   R=0,   B=150
]

(150, 0, 0) in GRB format = G=150, R=0, B=0 → dim green. To write red, use (0, 150, 0): G=0, R=150, B=0.

2.3 Seven-Color Rainbow List

This experiment predefines 7 rainbow colors and cycles through them by array index:

2.4 Core API — neopixel

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from machine import Pin
from neopixel import NeoPixel

np = NeoPixel(Pin(48), 1)     # GPIO48, 1 LED
np[0] = (150, 0, 0)            # set LED 0 to red (GRB)
np.write()                     # send the color data to the LED

np[0] = (g, r, b) only modifies the buffer in memory; you must call np.write() to actually send it to the LED.

3. Hardware Dependencies

The WS2812 on this board is onboard; no external components are required.

4. Project Architecture and Flow

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Script execution (single-file .py)
  │
  ├─ Config: LED_PIN=48, INTERVAL=1000ms
  ├─ RAINBOW = [7 GRB colors]                    // predefined color array
  ├─ np = NeoPixel(Pin(48), 1)                   // 1 WS2812
  ├─ color_index = 0                             // color index
  │
  └─ while True:                                 // cycle switching
       ├─ print("Current color: ...")             // print the current color name
       ├─ np[0] = RAINBOW[color_index]           // set the color
       ├─ np.write()                              // send to the LED
       ├─ color_index = (index + 1) % 7          // cycle the index
       └─ sleep_ms(1000)                          // 1s interval

5. Source Code Details

Full source code: 5.Source Code → MicroPython → 1.Basic Peripherals → 8.RGB → 8.RGB.py

5.1 Parameter Configuration and Color Definition

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from machine import Pin        # Pin class
from neopixel import NeoPixel  # WS2812 driver
import time                    # delay

# Configuration parameters
LED_PIN  = 48                # LED data pin
LED_NUM  = 1                 # number of LEDs
INTERVAL = 1000              # color switch interval (ms)

# Seven rainbow colors (GRB order, WS2812 native format)
RAINBOW = [
    (150, 0,   0),            # Red     (R=150, G=0,   B=0)
    (150, 60,  0),            # Orange  (R=150, G=60,  B=0)
    (150, 150, 0),            # Yellow  (R=150, G=150, B=0)
    (0,   150, 0),            # Green   (R=0,   G=150, B=0)
    (0,   150, 150),          # Cyan    (R=0,   G=150, B=150)
    (0,   0,   150),          # Blue    (R=0,   G=0,   B=150)
    (120, 0,   150),          # Purple  (R=120, G=0,   B=150)
]

COLOR_NAMES = ["Red", "Orange", "Yellow", "Green", "Cyan", "Blue", "Purple"]

5.2 Initialization and Cycle Switching

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# Init NeoPixel (WS2812, GPIO48)
np = NeoPixel(Pin(LED_PIN), LED_NUM)

color_index = 0

while True:
    print("Current color: %s" % COLOR_NAMES[color_index])  # print color

    np[0] = RAINBOW[color_index]  # write to buffer
    np.write()                    # send to LED

    color_index = (color_index + 1) % len(RAINBOW)  # cycle index
    time.sleep_ms(INTERVAL)

(color_index + 1) % len(RAINBOW) wraps the index back to 0: 6→7→0→1... .

6. Operation Procedure

6.1 Flashing and Running

Thonny IDE steps: See the 1. Before Development → 3.Thonny IDE chapter.

6.2 Normal Phenomenon

• The RGB LED switches to one color per second: red→orange→yellow→green→cyan→blue→purple→red, repeating

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  Current color: Red
  Current color: Orange
  Current color: Yellow
  Current color: Green
  Current color: Cyan
  Current color: Blue
  Current color: Purple
  Current color: Red       ← cycle
  ...
  

  

• The Shell prints the current color name every second

6.3 Verification Methods

7. Common Problems