MNL: Networked LED Lighting

MNL is a multi-node high-power RGB lighting system. It consists of a controller (PC or embedded system) and multiple light nodes networked with RS485. The first prototype nodes are up and running, and we will be developing the second revision of prototypes in the coming months. Read on past the break for more information.

Node Hardware

The node board is a small PCB with two RJ-45 ports and a power terminal strip, along with an ICSP header for flashing firmware. The nodes are designed for daisy-chaining both data and power.

Current features:

  • RS485 communication
  • Supports LEDs of up to 1.2A per channel
  • Upgradeable firmware for additional features
  • TBD: Firmware updates over RS485
  • Multiple fade types, dwell modes, etc.
  • Hardware-agnostic network supports different types of nodes (e.g., strobe, motor driver, etc)

LED Circuit

The LED used for prototyping is a 10W RGB LED from DealExtreme, which provides a generous amount of light with low cost per lumen. Although the heatsink is a bit small, forced-air cooling keeps things at a reasonable temperature.  The PCB includes a fan output which is PWMed according to the average instantaneous luminosity of the node. Forced-air cooling could be helpful for installation in compromising environments, such as can lighting fixtures.

The current design incorporates 3 current-limiting resistors for each channel of the LED. Although this is less efficient than current-regulated supplies, it allows flexibility in LED choice without requiring extensive PCB modifications.

Prototype Software

I developed a quick Processing sketch for testing purposes. It creates a FFT of the stereo mix and uses the lowest three bins to determine R/G/B brightness. If the largest of the three values is over the threshold specified by the slider, then an update command is sent to the node. The processing sketch also has an Open Sound Control (OSC) interface, allowing easy control from the TouchOSC app for iPhone or Android over WIFI as well as any software package that supports OSC.

This project is still under heavy development, and is still in the prototype phase. We are adding additional features to the software and hardware, so expect significant updates in the coming months.

Ethan is a computer engineer and open source hardware/software developer from Michigan. He enjoys AVR and linux development, photography, mountain biking, and drinking significant amounts of home-roasted coffee. Find out more at

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2 comments on “MNL: Networked LED Lighting
  1. Seth says:

    I would like to play that processing sketch. Are you planning on open-sourcing it?

    • Hey Seth, I’ll probably get the source up in my repository in the next couple of weeks. I have an updated sketch with an OSC interface for control from an Android phone as well as some other improvements.

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