WLED chain is a board for the WLED firmware, allowing to power, control, and chain them over Ethernet cables.

purpose

The WLED firmware is ideal do control addressable LEDs strip. WLED chain is a hardware board for it, matching my usage: robust remotely controlled LED strip based light installations for festivals. It allows to:

• use of the shelf 12-24V power supplies to power the 5V LED strips
• inter-connect them to form long chains (only connecting the first to externally provided power and data)
• use cheap Ethernet CAT5E cables to inter-connect them (also over long distances)
• provide power and data over the Ethernet cables
• proper 5V LED data signal output (up to three of them)

usage

background

origin

WLED is a very good firmware to control addressable LED such as the WS2812b. Just get a cheap ESP32 development board, flash WLED using the web installer, and of you got. I did that very often, and for small projects its fine. But for larger projects with multiple devices, you encounter some limitations:

• you have to separately take care of the power supply: LED strips can draw a lot of current which the development board can not handle
• remote control using ArtNet over WiFi can be problematic: WiFi routers don't all handle broadcast well, WiFi coverage is not always good, WiFi is jittery
• providing power to multiple device can be a pain: there is not always a power plug nearby

this project tries to solve these issues, and since I designed a board, provide even more features

bus

The first problem is WiFi:

• ESP32 operate on 2.4 GHz, a crowded spectrum
• ESP32 board with built-in antenna have poor reception
• WiFi router don't always handle broadcast well

This make the WiFi a poor interface to remotely control LEDs with multiple WLED (using ArtNet or similar) in a real-time manner (low latency and jitter).

The first solution would be to use Ethernet instead of WiFi. This would keep the networking capability. ESP32 supports this interface, and the WT32-ETH01 makes it available. But to connect multiple devices you need a Ethernet switch, and run wires from this switch to each device (e.g. is a star topology). I wanted to be able to chain the devices, to increase the distance while reducing number of cables and their length.

You could use the KSZ8863 3-port Ethernet PHY. This can act as Ethernet interface for the ESP32, and built-in switch. Now the boards can be chained. There is already schematic available, but the support still is beta, and the implementation is complex are not inexpensive.

I also though about CAN bus. This is a very resilient bus, and the ESP32 has an interface for it. But WLED does not support it yet, and the host would need a bridge for it.

Finally I arrived to RS-285. It's another differential protocol, often used in the industry because resilient. And the implementation is WLED is easy because it's just serial. This is when I remembered that DMX512 also uses RS-485. And DMX is the de facto standard in the lighting event world. Thus interface with is will be very easy and there is a lot of software support. The limitation is that it supports only one universe of 512 channels, or 170 RGB LEDs. A solution would be to control modes instead of individual LEDs.

features

Here a wish list of features in decreasing order:

• daisy chain capability (providing data and power)
• built-in power 5V power supply (input up to 30V)
• RS-485/DMX512 interface (not isolated)
• RJ45 port (2x for daisy chain)
• RJ45 pin header (to solder wires directly)
• DC barrel jack power input
• RJ45 power input
• proper 5V DOUT for WS2812B IC input
• external WiFi antenna port
• microphone/line in for sound reactive (use ESP32-LyraT-Mini design as reference)
• sonoff waterproof enclosure format
• XLR port (to fit usual DMX512 installations)
• fully isolated DMX512
• RDM support (requires adding bias on RS-485, and mostly software support)
• Lithium battery input and charger (not really the intended use scenario for this device)
• automotive fuse protection
• high voltage input (up to 60V, using TPS54560DDAR)
• USB Power Delivery power input (using IP2721 or FUSB302)

I'll probably add them with each new version

other

Here a list of other similar LED controllers:

• QuinLED-Dig-Quad: WLED compatible, but not DMX or power supply
• SP201E: cheap DMX512 LED strip controller, but no WLED, RJ45, or power supply
• H807DMX: compatible with most LED strips, and has RJ45 DMX512 input, but no WLED or power supply