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NeoPixel Lab

NeoPixel Demo Lab

The Maker Pi RP2040 comes with two built-in NeoPixels. Each NeoPixel has a red, green and blue LED inside it. Each of these LEDs can be set to any one of 256 values from 0 (off) to 255 (brightest value).

NeoPixel Setup

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from neopixel import Neopixel

NUMBER_PIXELS = 2
STATE_MACHINE = 0
LED_PIN = 18

# The Neopixels on the Maker Pi RP2040 are the GRB variety, not RGB
strip = Neopixel(NUMBER_PIXELS, STATE_MACHINE, LED_PIN, "GRB")

In this lab, we will turn the first NeoPixel element on red for 1/2 second and then turn it off for 1/2 second. We repeat this until the program is terminated.

Setting up the NeoPixel Library

We will be calling a NeoPixel driver in the /lib directory. We initiaze our NeoPixel strip by calling the init method all Neopixel() and pass it three parameters:

  1. The number of pixels in the strip (in our case there are just two)
  2. The state machine (in our case 0)
  3. The LED PIN (in our case this is GP18)
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from utime import sleep
# We are using https://github.com/blaz-r/pi_pico_neopixel
from neopixel import Neopixel

NUMBER_PIXELS = 2
STATE_MACHINE = 0
LED_PIN = 18

# The Neopixels on the Maker Pi RP2040 are the GRB variety, not RGB
strip = Neopixel(NUMBER_PIXELS, STATE_MACHINE, LED_PIN, "GRB")

while True:
    # turn on first pixel red for 1/2 second
    strip.set_pixel(0, (255, 0, 0))
    strip.show()
    sleep(.5)   
    strip.set_pixel(0, (0, 0, 0)) # turn all colors off
    strip.show()
    sleep(.5)

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import time
# We are using https://github.com/blaz-r/pi_pico_neopixel
from neopixel import Neopixel

NUMBER_PIXELS = 2
STATE_MACHINE = 0
LED_PIN = 18

# The Neopixels on the Maker Pi RP2040 are the GRB variety, not RGB
strip = Neopixel(NUMBER_PIXELS, STATE_MACHINE, LED_PIN, "GRB")

# Color RGB values
red = (255, 0, 0)
orange = (255, 60, 0) # Gamma corrected from G=128 to be less like yellow
yellow = (255, 150, 0)
green = (0, 255, 0)
blue = (0, 0, 255)
indigo = (75, 0, 130) # purple?
violet = (138, 43, 226) # mostly pink
color_names = ('red', 'orange', 'yellow', 'green', 'blue', 'indigo', 'violet')
num_colors = len(color_names)
colors = (red, orange, yellow, green, blue, indigo, violet)

# set to be 1 to 100 for percent brightness
strip.brightness(100)

color_index = 0
while True:
    for color in colors:
        for i in range(NUMBER_PIXELS):
            print(i, color_names[color_index])
            strip.set_pixel(i, color)
            strip.show()
            time.sleep(1)
        color_index += 1
        if color_index >= num_colors: color_index = 0