LED Strips

The 4 types of LED strips that the plugin supports are:

• WS2811 (including B variants)

• WS2812 (including B variants)

• SK6812 RGB

• SK6812 RGBW

Please note as well that 'NeoPixels' are an Adafruit brand name, I find that they are much cheaper direct from China with just as good results, they are the same thing.

Power Supplies

There are no officially-supported models for power supplies, since they are all the same. However, please make sure you are using an external power supply and not using the RPi GPIO pins to power the LEDs. They cannot provide the power drawn by a strip of WS281x LEDs.

Don't use tiny wires to connect the LEDs - these can heat up and melt if they are too thin.

Level Shifting

I have had good results with a 74ACHT125 level shifter, which is recommended by Adafruit for their Neopixels. Please note that while WS281x LEDs work without level shifting, you may need to keep the wires as short as possible - especially when using 12V LEDs.

Raspberry Pi

All models of Raspberry Pi are supported currently, however for new models I will have to wait for upstream support from the rpi-ws281x library first. This page will be updated if this happens!

This also means that no other devices than a Raspberry Pi are supported. There are no alternative libraries for WS281x LED control (for Python) that could enable this, so there is nothing that can be done. Sorry!

The plugin will not load if it is not running on a Raspberry Pi, even if it does install.

Got the necessary hardware? Wire it up!

The plugin uses the Raspberry Pi's SPI interface to push data to the LED strip, rather than PWM since it doesn't need to be run as root to use SPI.

As a result of this, there are a couple of OS level configuration items that need to be handled. Luckily for you, the plugin makes this very easy for you to do by providing a UI to run the commands.

Initial Setup Wizard & OS Configuration Test

The setup wizard requires root access, and therefore the password for the Pi user if you have not configured passwordless sudo, as is default on OctoPi. This password is not stored, and is only used for the steps below.

• Add the pi user to the gpio group.

  Already configured on most OS images. Means the pi users can access the GPIO pins.

  • Runs sudo adduser pi gpio

• Enable SPI. The plugin uses SPI to drive the LEDs, which is disabled by default and needs to be turned on.

  • Adds dtparam=spi=on to /boot/config.txt

• Increase SPI buffer size. Whilst the plugin will work without this, it will only work well with a handful of LEDs, so the buffer size must be increased to control more LEDs.

  • Adds spidev.bufsiz=32768 to the end of /boot/cmdline.txt

• Set compatible clock frequency Raspberry Pi 3 or earlier only, not required for a Pi 4 The Pi 3's default internal clock frequency is not compatible with SPI, so it needs to be set to 250 to be compatible.

  • Adds core_freq=250 to /boot/config.txt

• Set a minimum clock frequency Raspberry Pi 4 only On a Raspberry Pi 4, the clock frequency is dynamic and can change when the pi is 'idle' vs. 'working', which causes LEDs to flicker, change colour, or stop working completely. By setting a minimum the same as the max, we stop this dynamic clocking.

  • Adds core_freq_min=500 to /boot/config.txt

Final stage: Initial Configuration

WS281x LEDs are very simple to wire with their 3 LEDs. There are three options of how to wire, each detailed below.

Raspberry Pi Wiring

The hardest part about wiring with a Raspberry Pi is connecting up the 3.3v logic from the Pi to the strip that wants 5v. There are several ways you can do this, which are described in more detail below.

No Level Shifting

It is possible to connect the LEDs up without any kind of level shifting, however mileage varies from strip to strip. I have one setup like this, and one with the full logic shifter. This can work because the spec of the LED strips means they need 0.7 * VDD(5v) which is ~3.5v. Close to the Pi's 3.3, so depending on how tight of a tolerance your strip has, this is possible.

Wiring is as follows:

• Pi GND to LED GND

• Pi GPIO 10 to LED Data in

• Power supply GND to LED GND

• Power supply 5V to LED 5V

Level Shifting Chip

You can use a level shifting chip to convert the signals from 3.3v to 5v. Recommended one to use is a 74AHCT125, I have this and it works well.

Wiring of this is as follows:

• Common ground between:

  • Pi GND

  • LED GND

  • Power Supply GND

  • 74AHCT125 GND

  • 74AHCT125 pin 1OE

• Pi GPIO 10 to 74AHCT125 pin 1A

• 74AHCT125 pin 1Y to LED Data in

• Power supply 5V to:

  • 74AHCT125 VCC

  • LED 5V

Wiring with a Diode

The diode method is a quick way to reduce the power supply voltage slightly, so that the LED strip can read the 3.3v.

Wiring is as follows:

• Pi GPIO 10 to LED Data in

• Power supply 5V to 1N4001 diode anode (side without the stripe)

• 1N4001 diode cathode (side with the stripe) to LED 5V

• Power supply GND to Pi GND

• Power supply GND to LED GND

On to the next stage: SPI setup

I've tried to make this setup process as simple as possible, while it was already easy it is even easier with this guide.

Installation

Install the plugin via OctoPrint's bundled or manually using this URL:

Once you have installed and enabled the plugin, OctoPrint will prompt you to restart the server.

Check you have the right hardware:

Next up: Wiring your LEDs

Open the plugin's entry in OctoPrint's settings interface, and you should be presented with this view:

Click on the 'LED Strip Settings' button in the top right. The key settings you should edit are listed below:

• Strip Type Select the type of strip you have connected to your Pi. Note: This may not be exactly what you were sold, sometimes they send variations. If you have issues, please try similar strip types here.

• Number of LEDs This should be easy, count the number of LEDs you have connected and enter the right number!

• Max Brightness This setting controls the maximum brightness that your LEDs should reach.