OctoWS2811 Adapter and Internet

[mlathrop]

Hello! I wanted to see if the octoWS2811 adapter is built in a way that would allow one of the two ethernet ports to be used as a port for network access. For example I would like to have one of the ports be an "In" port receiving images from a computer and the other being an "out" to the LEDs.

Anyone have any thoughts on feasibility?

-Matt

 

[MichaelMeissner]

Well it might be possible to hook up a Teensy to a separate ethernet/wifi and the octows2811 adapter, but I suspect it wouldn't be via the octows2811's cat6 ports. Instead, you would hook up a separate network adapter, and hook the network connection to that. Network adapters push a lot of the network processing to the off-board processor. Even if you wanted to bit-bang interfaces, you would have to deal with voltage issues (I believe ethernet runs at +/- 2.5v, and the Teensy runs at +3.3v).

Looking at the wiring diagram, you could either hook up a network adapter to the SPI pins (10-13, plus use 9 for reset which isn't used by the octows2811) or via Serial1 as a UART (pins 0/1). The WIZ820io adaptor pcb that PJRC.com sells uses the SPI pins (the SD adapter that is also part of the board wouldn't be used). You can get various ethernet/wifi adapters that are meant to be used with UART's (i.e. Serial1).

Note that when you are running lots and lots of lights, I would imagine the Teensy is running a lot with interrupts disabled to do the timing for LED strings, so it may not work as well with networking. In addition, the network stacks on embedded systems tend to be fairly thin, so either you have to spend a lot of time adding support for things you might have on a system more geared towards network support, or you have to be very focused in what the Teensy supports. It might be better to get a Raspberry Pi B/B+ to handle the networking, and then talk to the Teensy to give it commands of what to do with the LEDs over Serial1.

 

[GremlinWrangler]

As MichaelMeissner states, the RJ45 ports on the board are not Ethernet. They are there purely to provide an easy way to get LED data onto cheap twisted pair cables. They are output only and while they probably wouldn't do any harm having ethernet connected certainly cannot work.

Most ethernet driven lighting systems have gravitated to a raspberry pi or equivalent 'real' computer to provide the interface and streamed serial data to one or more Teenys.

 

[PaulStoffregen]

Many people have built LED lighting projects using Artnet protocol, with Teensy 3.1, the OctoWS2811 board, the Wiz820+SD adaptor, and a WIZ820io module. That's a tall stack-up of 4 boards, but it works pretty well.

The main compelling reason to go down that 4-board-stackup path is existing (usually proprietary) LED lighting software than speaks Arnet protocol over ethernet. The WIZ820 has moderate performance. I've heard people talk of controlling 4+ DMX universes, which is pretty good for low cost Arnet. If your project revolves around such lighting software (by far the most expensive part) this is a pretty attractive way to go.

But WIZ820 communication falls far short of OctoWS2811's raw capability using only the far more efficient USB port. A single Teensy can control about 4000 LEDs that way, easily achieving video rate refresh across all LEDs.

If you're writing your own software, or using hackable open source software, a tiered network where Raspberry Pi receives ethernet communication and feeds data to several Teensy can drive an incredible number of LEDs at very low cost.

However, as a practical matter, Teensy and Raspberry Pi are the least expensive part of such large LED projects. The LEDs and power supplies cost far more. Often costs for mundane things, like construction materials, connectors, and protective covers or packaging for transport between locations end up costing far more than the electronics. Sometimes focusing solely on the electronics cost ends up being penny-wise but pound foolish. A design that optimizes for easy servicing of all parts in a modular manner ends up saving money in the end, not to mention tremendous frustration.