WS2812B (NeoPixel) strip with Raspberry Pi Pico W

On the Pico W, WS2812B strips are a MicroPython one-liner: neopixel.NeoPixel(Pin(16), 8). The RP2040’s programmable I/O generates the 800 kHz signal in hardware.

Power a short strip from VBUS (USB 5 V) and keep the brightness low; anything longer gets its own 5 V supply with a shared ground.

Wiring

Also needed: 330 Ω resistor, 1000 µF capacitor for strips on their own supply.

Every connection
Raspberry Pi Pico W	WS2812B addressable RGB LED strip (NeoPixel)	Wire	Notes
GP16	DIN	green	Via 330 Ω — GP16 is physical pin 21.
VBUS	5V	red	VBUS is USB 5 V (pin 40) — only present when the Pico runs from USB. Longer strips need their own 5 V supply with a common GND.
GND	GND	black

5 V (about 60 mA per LED at full white) part, 3.3 V board. The strip expects a data HIGH of about 3.5 V at 5 V supply. From ESP32 or Pico the 3.3 V signal often works with short wires, but to be safe drive DIN through a 74AHCT125 (or 74HCT125) powered from 5 V.

Board quirks

MicroPython’s neopixel module uses the RP2040’s PIO, so timing is exact without any library to install.
The strip is 5 V and the Pico’s data is 3.3 V — fine on short wires; add a 74AHCT125 buffer if the first LED flickers.
Brightness is scaled to 15 % in code to keep a short strip within USB limits.

Code

main.pyMicroPython

# WS2812B LED strip (8 LEDs) on a Raspberry Pi Pico W with the built-in neopixel module.
# DIN -> GP16 (pin 21) through a 330 ohm resistor, strip 5V -> VBUS (pin 40, USB 5 V), GND -> GND.
from machine import Pin
import neopixel
import time

LED_COUNT = 8
BRIGHTNESS = 0.15  # keeps a short strip well inside what USB can supply
strip = neopixel.NeoPixel(Pin(16), LED_COUNT)


def wheel(pos):
    """0-255 colour wheel -> (r, g, b)."""
    pos %= 256
    if pos < 85:
        return (255 - pos * 3, pos * 3, 0)
    if pos < 170:
        pos -= 85
        return (0, 255 - pos * 3, pos * 3)
    pos -= 170
    return (pos * 3, 0, 255 - pos * 3)


print("WS2812B rainbow on GP16")
offset = 0
while True:
    for i in range(LED_COUNT):
        r, g, b = wheel(offset + i * 256 // LED_COUNT)
        strip[i] = (int(r * BRIGHTNESS), int(g * BRIGHTNESS), int(b * BRIGHTNESS))
    strip.write()
    offset = (offset + 4) % 256
    time.sleep_ms(20)

# WS2812B LED strip (8 LEDs) on a Raspberry Pi Pico W with the built-in neopixel module.
# DIN -> GP16 (pin 21) through a 330 ohm resistor, strip 5V -> VBUS (pin 40, USB 5 V), GND -> GND.
from machine import Pin
import neopixel
import time

LED_COUNT = 8
BRIGHTNESS = 0.15  # keeps a short strip well inside what USB can supply
strip = neopixel.NeoPixel(Pin(16), LED_COUNT)


def wheel(pos):
    """0-255 colour wheel -> (r, g, b)."""
    pos %= 256
    if pos < 85:
        return (255 - pos * 3, pos * 3, 0)
    if pos < 170:
        pos -= 85
        return (0, 255 - pos * 3, pos * 3)
    pos -= 170
    return (pos * 3, 0, 255 - pos * 3)


print("WS2812B rainbow on GP16")
offset = 0
while True:
    for i in range(LED_COUNT):
        r, g, b = wheel(offset + i * 256 // LED_COUNT)
        strip[i] = (int(r * BRIGHTNESS), int(g * BRIGHTNESS), int(b * BRIGHTNESS))
    strip.write()
    offset = (offset + 4) % 256
    time.sleep_ms(20)

Expected serial output

REPL / Thonny shellOutput

WS2812B rainbow on GP16

WS2812B rainbow on GP16

Common errors

First LED flickers or shows the wrong colour

Marginal 3.3 V data. Keep the data wire short and the 330 Ω resistor in place, or add a buffer.

Pico resets when LEDs turn white

Too much current from USB. Lower the brightness or give the strip its own supply.