NeoPixels are a revolutionary and ultra-popular way to add lights and color to your project. These stranded RGB lights have the controller inside the LED, so you just push the RGB data and the LEDs do all the work for you. They're a perfect match for CircuitPython!
You can drive 300 NeoPixel LEDs with brightness control (set brightness=1.0 in object creation) and 1000 LEDs without. That's because to adjust the brightness we have to dynamically recreate the data-stream each write.
Wiring It Up
You'll need to solder up your NeoPixels first. Verify your connection is on the DATA INPUT or DIN side. Plugging into the DATA OUT or DOUT side is a common mistake! The connections are labeled and some formats have arrows to indicate the direction the data must flow.
For powering the pixels from the board, the 3.3V regulator output can handle about 500mA peak which is about 50 pixels with 'average' use. If you want really bright lights and a lot of pixels, we recommend powering direct from an external power source.
- On Gemma M0 and Circuit Playground Express this is the Vout pad - that pad has direct power from USB or the battery, depending on which is higher voltage.
- On Trinket M0, Feather M0 Express, Feather M4 Express, ItsyBitsy M0 Express and ItsyBitsy M4 Express the USB or BAT pins will give you direct power from the USB port or battery.
- On Metro M0 Express and Metro M4 Express, use the 5V pin regardless of whether it's powered via USB or the DC jack.
- On QT Py M0, use the 5V pin.
If the power to the NeoPixels is greater than 5.5V you may have some difficulty driving some strips, in which case you may need to lower the voltage to 4.5-5V or use a level shifter.
The Code
This example includes multiple visual effects.
To use with CircuitPython, you need to first install a few libraries, into the lib folder on your CIRCUITPY drive. Then you need to update code.py with the example script.
Thankfully, we can do this in one go. In the example below, click the Download Project Bundle button below to download the necessary libraries and the code.py file in a zip file. Extract the contents of the zip file, open the directory CircuitPython_Essentials/CircuitPython_NeoPixel/ and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your CIRCUITPY drive.
Your CIRCUITPY drive should now look similar to the following image:
# SPDX-FileCopyrightText: 2018 Kattni Rembor for Adafruit Industries
#
# SPDX-License-Identifier: MIT
"""CircuitPython Essentials NeoPixel example"""
import time
import board
from rainbowio import colorwheel
import neopixel
pixel_pin = board.A1
num_pixels = 8
pixels = neopixel.NeoPixel(pixel_pin, num_pixels, brightness=0.3, auto_write=False)
def color_chase(color, wait):
for i in range(num_pixels):
pixels[i] = color
time.sleep(wait)
pixels.show()
time.sleep(0.5)
def rainbow_cycle(wait):
for j in range(255):
for i in range(num_pixels):
rc_index = (i * 256 // num_pixels) + j
pixels[i] = colorwheel(rc_index & 255)
pixels.show()
time.sleep(wait)
RED = (255, 0, 0)
YELLOW = (255, 150, 0)
GREEN = (0, 255, 0)
CYAN = (0, 255, 255)
BLUE = (0, 0, 255)
PURPLE = (180, 0, 255)
while True:
pixels.fill(RED)
pixels.show()
# Increase or decrease to change the speed of the solid color change.
time.sleep(1)
pixels.fill(GREEN)
pixels.show()
time.sleep(1)
pixels.fill(BLUE)
pixels.show()
time.sleep(1)
color_chase(RED, 0.1) # Increase the number to slow down the color chase
color_chase(YELLOW, 0.1)
color_chase(GREEN, 0.1)
color_chase(CYAN, 0.1)
color_chase(BLUE, 0.1)
color_chase(PURPLE, 0.1)
rainbow_cycle(0) # Increase the number to slow down the rainbow
Create the LED
The first thing we'll do is create the LED object. The NeoPixel object has two required arguments and two optional arguments. You are required to set the pin you're using to drive your NeoPixels and provide the number of pixels you intend to use. You can optionally set brightness and auto_write.
NeoPixels can be driven by any pin. We've chosen A1. To set the pin, assign the variable pixel_pin to the pin you'd like to use, in our case board.A1.
To provide the number of pixels, assign the variable num_pixels to the number of pixels you'd like to use. In this example, we're using a strip of 8.
We've chosen to set brightness=0.3, or 30%.
By default, auto_write=True, meaning any changes you make to your pixels will be sent automatically. Since True is the default, if you use that setting, you don't need to include it in your LED object at all. We've chosen to set auto_write=False. If you set auto_write=False, you must include pixels.show() each time you'd like to send data to your pixels. This makes your code more complicated, but it can make your LED animations faster!
NeoPixel Helpers
Next we've included a few helper functions to create the super fun visual effects found in this code. First is wheel() which we just learned with the Internal RGB LED. Then we have color_chase() which requires you to provide a color and the amount of time in seconds you'd like between each step of the chase. Next we have rainbow_cycle(), which requires you to provide the mount of time in seconds you'd like the animation to take. Last, we've included a list of variables for our colors. This makes it much easier if to reuse the colors anywhere in the code, as well as add more colors for use in multiple places. Assigning and using RGB colors is explained in this section of the CircuitPython Internal RGB LED page.
Main Loop
Thanks to our helpers, our main loop is quite simple. We include the code to set every NeoPixel we're using to red, green and blue for 1 second each. Then we call color_chase(), one time for each color on our list with 0.1 second delay between setting each subsequent LED the same color during the chase. Last we call rainbow_cycle(0), which means the animation is as fast as it can be. Increase both of those numbers to slow down each animation!
Note that the longer your strip of LEDs, the longer it will take for the animations to complete.
NeoPixel RGBW
NeoPixels are available in RGB, meaning there are three LEDs inside, red, green and blue. They're also available in RGBW, which includes four LEDs, red, green, blue and white. The code for RGBW NeoPixels is a little bit different than RGB.
If you run RGB code on RGBW NeoPixels, approximately 3/4 of the LEDs will light up and the LEDs will be the incorrect color even though they may appear to be changing. This is because NeoPixels require a piece of information for each available color (red, green, blue and possibly white).
Therefore, RGB LEDs require three pieces of information and RGBW LEDs require FOUR pieces of information to work. So when you create the LED object for RGBW LEDs, you'll include pixel_order=(1, 0, 2, 3), which sets the pixel order and indicates four pieces of information involved.
Then, you must include an extra number in every color tuple you create. For example, red will be (255, 0, 0, 0). This is how you send the fourth piece of information. Check out the example below to see how our NeoPixel code looks for using with RGBW LEDs!
The Code
To use with CircuitPython, you need to first install a few libraries, into the lib folder on your CIRCUITPY drive. Then you need to update code.py with the example script.
Thankfully, we can do this in one go. In the example below, click the Download Project Bundle button below to download the necessary libraries and the code.py file in a zip file. Extract the contents of the zip file, open the directory CircuitPython_Essentials/CircuitPython_NeoPixel_RGBW/ and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your CIRCUITPY drive.
Your CIRCUITPY drive should now look similar to the following image:
# SPDX-FileCopyrightText: 2018 Kattni Rembor for Adafruit Industries
#
# SPDX-License-Identifier: MIT
"""CircuitPython Essentials NeoPixel RGBW example"""
import time
import board
import neopixel
pixel_pin = board.A1
num_pixels = 8
pixels = neopixel.NeoPixel(pixel_pin, num_pixels, brightness=0.3, auto_write=False,
pixel_order=(1, 0, 2, 3))
def colorwheel(pos):
# 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, 0)
if pos < 85:
return (255 - pos * 3, pos * 3, 0, 0)
if pos < 170:
pos -= 85
return (0, 255 - pos * 3, pos * 3, 0)
pos -= 170
return (pos * 3, 0, 255 - pos * 3, 0)
def color_chase(color, wait):
for i in range(num_pixels):
pixels[i] = color
time.sleep(wait)
pixels.show()
time.sleep(0.5)
def rainbow_cycle(wait):
for j in range(255):
for i in range(num_pixels):
rc_index = (i * 256 // num_pixels) + j
pixels[i] = colorwheel(rc_index & 255)
pixels.show()
time.sleep(wait)
RED = (255, 0, 0, 0)
YELLOW = (255, 150, 0, 0)
GREEN = (0, 255, 0, 0)
CYAN = (0, 255, 255, 0)
BLUE = (0, 0, 255, 0)
PURPLE = (180, 0, 255, 0)
while True:
pixels.fill(RED)
pixels.show()
# Increase or decrease to change the speed of the solid color change.
time.sleep(1)
pixels.fill(GREEN)
pixels.show()
time.sleep(1)
pixels.fill(BLUE)
pixels.show()
time.sleep(1)
color_chase(RED, 0.1) # Increase the number to slow down the color chase
color_chase(YELLOW, 0.1)
color_chase(GREEN, 0.1)
color_chase(CYAN, 0.1)
color_chase(BLUE, 0.1)
color_chase(PURPLE, 0.1)
rainbow_cycle(0) # Increase the number to slow down the rainbow
Read the Docs
For a more in depth look at what neopixel can do, check out NeoPixel on Read the Docs.
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