2. LED progressions
2.1. Colour lists
A list of colours can be used to create a colourful display.
Two for-loops are used, one nested inside the other.
for c in colour_list: loops through the colours.for i in range(4): loops through each LED to set the colour for it.This example requires a strip of 4 Neopixels (WS2812) connected to pin8.
from microbit import *
import neopixel
white = (255, 255, 255)
red = (255, 0, 0)
yellow = (255, 255, 0)
green = (0, 128, 0)
cyan = (0, 255, 255)
blue = (0, 0, 255)
magenta = (255, 0, 255)
colour_list = [white, red, yellow, green, cyan, blue, magenta, ]
lights = neopixel.NeoPixel(pin8, 4)
for c in colour_list:
for i in range(4):
lights[i]=c
lights.show()
sleep(200)
Tasks
See https://www.indezine.com/products/powerpoint/learn/color/color-rgb.html
Modify the code to use a shorter list of colours, with just the primary colours.
Modify the code to use a shorter list of colours, with just the secondary colours.
2.2. Random brightness
Repeatedly display random colours on the LED strip.
This example requires a strip of 4 Neopixels (WS2812) connected to pin8.
from microbit import *
import neopixel
from random import randint
# Setup the Neopixel strip on pin8 with a length of 4 pixels
lights = neopixel.NeoPixel(pin8, 4)
while True:
#Iterate over each LED in the strip
for pixel_id in range(0, len(lights)):
red = randint(0, 60)
green = randint(0, 60)
blue = randint(0, 60)
# Assign the current LED a random red, green and blue value between 0 and 60
lights[pixel_id] = (red, green, blue)
# Display the current pixel data on the Neopixel strip
lights.show()
sleep(100)
2.3. Random colours
Repeatedly display random colours on the 4 LEDs connected to pin8.
This example requires a strip of 4 Neopixels (WS2812) connected to pin8.
from microbit import *
import neopixel
import random
# Setup the Neopixel strip on pin8 with a length of 4 pixels
lights = neopixel.NeoPixel(pin8, 4)
def same_random_pixels():
# Iterate over each LED in the strip
red = random.randint(0, 255)
green = random.randint(0, 255)
blue = random.randint(0, 255)
for pixel_id in range(4):
# Assign the current LED a random red, green and blue value between 0 and 60
lights[pixel_id] = (red, green, blue)
# Display the current pixel data on the Neopixel strip
lights.show()
while True:
same_random_pixels()
sleep(400)
2.4. Front and rear lights
Display front lights as green and rear lights as red.
This example requires a strip of 4 Neopixels (WS2812) connected to pin8.
from microbit import *
import neopixel
import random
# Setup the Neopixel strip on pin8 with a length of 4 pixels
lights = neopixel.NeoPixel(pin8, 4)
def front_lights():
# LED 0 and 1; red, green and blue value between 0 and 255
lights[0] = (0, 255, 0)
lights[1] = (0, 255, 0)
# Display the current pixel data on the Neopixel strip
lights.show()
def rear_lights():
# LED 2 and 3; red, green and blue value between 0 and 255
lights[2] = (255, 0, 0)
lights[3] = (255, 0, 0)
# Display the current pixel data on the Neopixel strip
lights.show()
front_lights()
rear_lights()
2.6. Colour wheel
This code is used to create a rainbow color effect on a Neopixel strip.
The wheel function generates a color based on an input position, transitioning from red to green to blue and back to red. The rainbow function applies this color effect to each pixel in the Neopixel strip.
The color of each pixel is determined by its position in the strip, creating a rainbow effect.
The Neopixel strip is then updated to display the new colors.
This example requires a strip of 12 Neopixels connected to pin13.
from microbit import *
import neopixel
# Setup the Neopixel strip on pin13 with a length of 12 pixels
np = neopixel.NeoPixel(pin13, 12)
def wheel(pos):
"""
Generate color based on the input position, transitioning from red to green to blue and back to red. The rainbow function applies this color effect to each pixel in the Neopixel strip.
Parameters:
pos (int): Position value ranging from 0 to 255.
Returns:
tuple: Returns a color value as a tuple (R, G, B).
"""
# Input a value 0 to 255 to get a color value.
# The colours are a transition r - g - b - back to r.
if pos < 0 or pos > 255:
return (255,255,255)
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)
def rainbow(np):
"""
Generate a rainbow color effect on the Neopixel strip.
Parameters:
np (NeoPixel): The Neopixel strip object.
Returns:
None
"""
# Loop through each pixel in the strip.
for i in range(len(np)):
# Calculate the color index for the current pixel.
rc_index = (i * 256 // len(np)) % 256
# Set the color of the current pixel.
np[i] = wheel(rc_index)
# Update the Neopixel strip to display the colors.
np.show()
# Call the rainbow function to display the effect on the Neopixel strip.
rainbow(np)
2.7. Colour wheel with brightness control
This code is used to create a rainbow color effect on a Neopixel strip.
The wheel function uses a brightness_factor from 0 to 1 to dim the LEDs.
This example requires a strip of 12 Neopixels connected to pin13.
from microbit import *
import neopixel
# Setup the Neopixel strip on pin13 with a length of 12 pixels
np = neopixel.NeoPixel(pin13, 12)
def wheel(pos, brightness_factor=1):
"""
Generate color based on the input position and brightness factor.
Parameters:
pos (int): Position value ranging from 0 to 255.
brightness_factor (float): Brightness scaling factor ranging from 0.1 to 1.0.
Returns:
tuple: Returns a color value as a tuple (r, g, b).
"""
# Input a value 0 to 255 to get a color value.
# The colours are a transition r - g - b - back to r.
if pos < 0 or pos > 255:
return (0, 0, 0)
if pos < 85:
return (int((255 - pos * 3) * brightness_factor), int((pos * 3) * brightness_factor), 0) # scale down the brightness
if pos < 170:
pos -= 85
return (0, int((255 - pos * 3) * brightness_factor), int((pos * 3) * brightness_factor)) # scale down the brightness
pos -= 170
return (int((pos * 3) * brightness_factor), 0, int((255 - pos * 3) * brightness_factor)) # scale down the brightness
def rainbow(np, brightness_factor):
"""
Generate a rainbow color effect on the Neopixel strip.
Parameters:
np (NeoPixel): The Neopixel strip object.
Returns:
None
"""
# Loop through each pixel in the strip.
for i in range(len(np)):
# Calculate the color index for the current pixel.
rc_index = (i * 256 // len(np)) % 256
# Set the color of the current pixel.
np[i] = wheel(rc_index, brightness_factor)
# Update the Neopixel strip to display the colors.
np.show()
# Call the rainbow function to display the effect on the Neopixel strip.
rainbow(np, 0.01)
2.8. Rainbow cycle
This code is used to create a rainbow color effect on a Neopixel strip.
The wheel function generates a color based on the input position, and the rainbow_cycle function applies this color to each pixel in the Neopixel strip, creating a beautiful rainbow effect.
The effect continuously loops due to the while True loop at the end of the script.
This example requires a strip of 12 Neopixels connected to pin13.
from microbit import *
import neopixel
# Setup the Neopixel strip on pin13 with a length of 12 pixels
np = neopixel.NeoPixel(pin13, 12)
def wheel(pos, brightness_factor=1):
"""
Generate color based on the input position and brightness factor.
Parameters:
pos (int): Position value ranging from 0 to 255.
brightness_factor (float): Brightness scaling factor ranging from 0.1 to 1.0.
Returns:
tuple: Returns a color value as a tuple (r, g, b).
"""
# Input a value 0 to 255 to get a color value.
# The colours are a transition r - g - b - back to r.
if pos < 0 or pos > 255:
return (0, 0, 0)
if pos < 85:
return (int((255 - pos * 3) * brightness_factor), int((pos * 3) * brightness_factor), 0) # scale down the brightness
if pos < 170:
pos -= 85
return (0, int((255 - pos * 3) * brightness_factor), int((pos * 3) * brightness_factor)) # scale down the brightness
pos -= 170
return (int((pos * 3) * brightness_factor), 0, int((255 - pos * 3) * brightness_factor)) # scale down the brightness
def rainbow_cycle(np, wait, brightness_factor):
"""
Create a rainbow cycle effect on the Neopixel strip.
Parameters:
np (neopixel.NeoPixel): The Neopixel strip.
wait (int): The delay time in milliseconds.
brightness_factor (float): Brightness scaling factor ranging from 0.1 to 1.0.
"""
for j in range(0, 256, 12):
for i in range(len(np)):
rc_index = (i * 256 // len(np) + j) % 255
np[i] = wheel(rc_index, brightness_factor)
np.show()
sleep(wait)
brightness_factor = 0.5 # Set your desired brightness factor here
while True:
# Continuously display the rainbow cycle effect
rainbow_cycle(np, 100, 0.02)