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LED Project Enabler

Chromatron is an open source pixel controller designed to make LED pixel projects easy and fun.

Chromatron Features

  • LED Pixel Drivers

    Drive 300 pixels of a variety of types without additional circuitry or firmware modifications.

  • Pixel Graphics Pipeline

    Create high quality animation and fading effects with per-pixel faders, robust dimming controls, and 16 bit internal computations.

  • Control & program over WiFi

    Easily control and coordinate multiple devices wirelessly.

  • FX Scripting Engine

    Chromatron's FX Script is a simple language designed specifically for pixel graphics.

  • Python & Command Line APIs

    The Python library and CLI make it easy to integrate Chromatron into other projects.

  • And even more...

    Real-time pixel streaming, simple hardware connections, and much more.

API Examples

Discover, configure, and control devices over WiFi with our Python library and Command Line Interface tools:


from chromatron import *

# Discover devices in living room
group = DeviceGroup('living_room')

# Load rainbow effect script

# Set master dimmer to 50%
group.dimmer = 0.5

Command Line

# Install Python library
pip install chromatron

# Discover devices in living room
chromatron --query living_room discover

# Load rainbow FX script to previous group
chromatron vm load rainbow.fx

# Set master dimmer to 50%
chromatron dimmer master 0.5

Live code with FX Script

FX Script is a hybrid language based on Python syntax running on a custom designed virtual machine that makes it easy to generate graphics directly on hardware. FX can compile and load in real-time to get instant visual feedback.

# this script generates a rolling rainbow pattern

# declare a global variable for current hue
current_hue = Number()

# init - runs once when script is loaded
def init():
    # set pixels to full colors (maximum saturation)
    pixels.sat = 1.0

    # set to maximum brightness
    pixels.val = 1.0

# runs periodically, frame rate is configurable
def loop():
    # increment the base hue so the rainbow pattern
    # shifts across the pixels
    current_hue += 0.005

    # declare a local variable
    a = Number()
    a = current_hue

    # loop over all pixels in array
    for i in pix_count():
        pixels[i].hue = a

        # shift color for next iteration
        a += 1.0 / pix_count()


Chromatron hardware prototype.

Technical Specs

I/O Processor

  • Atmel AVR XMega128A4U
  • 32 MHz
  • 8K SRAM
  • 128K Flash

Runs the real time OS, handles raw pixel data output, USB, auxiliary IO, and the user file system.

WiFi/Graphics processor

  • Espressif ESP8266
  • 160 MHz
  • 64K RAM

Handles WiFi communications, scripting engine VM, pixel faders, and HSV to RGB colorspace conversion. Connected to the real time processor via 4 MHz UART bridge.


  • 4x PWM outputs, 3 amps each
  • 1x Pixel clock + data output with built in level shifters, multiplexed with 2 of the PWM channels
  • 2x power and ground connections
  • Micro USB port
  • 2x expansion IO headers for future use


  • 1.25 x 2 inches (the USB overhangs by another 0.1 inches or so)
side dimensions
side dimensions

About Us

Sapphire Open Systems is an Austin, TX based startup whose mission is to enable hobbyists, makers, and professionals to connect anything to everything and promote open source as a better way to make electronics.

100% Open Source

All software and hardware will be released under OSI compatible licenses once the project hits the funding goal.

Open Source Initiative logo

Open Source

Open Source Hardware logo

Open Source