WS2812B LED (NeoPixel) Control: Part 2 – WiFi Control via Art-Net on ESP8266


For wireless control of WS2812B (NeoPixel) LEDs, I initially played with Bluetooth SPP (Serial Port Profile), due to the simplicity of setting up the host software… from the host’s software’s point of view, the connection just looks like a physical serial port. Unfortunately, the flakiness of my Windows 8.1 PCs’ Bluetooth SPP support caused me to abandon that solution.


ESP8266 modules provide a very low cost method of interfacing WS2812Bs to WiFi. Adafruit’s Huzzah module costs $9.95, but on eBay, NodeMCU clones, such as the LoLin NodeMCU board can be had for ~$3 shipped from China. This makes it even cheaper than the Arduino/Bluetooth combination!

What’s more, the LoLin board has a CH340G onboard, so it doesn’t require a FTDI cable to connect it to your host computer for programming. I ordered a few of the LoLin boards, but in the meantime, I started playing with the Adafruit Huzzah boards I had on hand.

With the addition of ESP8266 support via the Board Manager, Arduino becomes an easy to use platform for code development. Also, there are easily obtainable libraries for both WiFi configuration and control of the WS2812Bs.

One extra complexity of using an ESP8266 to control WS2812Bs is that the ESP8266 is a 3.3V device, while the WS2812B is a 5V device, (usually) necessitating level shifting. The WS2812B datasheet shows a threshold of >= 0.7VDD for logic HIGH, and <= 0.3VDD for logic LOW. The allowed VDD ranges from +3.5-5.3V. Interestingly, some WS2812Bs can actually work when powered by 3.3V, and driven by 3.3V logic, even though it’s out of spec, but many cannot. On the other hand, it’s totally within spec to be powered by 3.7V and driven by 3.3V logic. So, if you use a 3.7V LiPo battery to power the WS2812B strand, the WS2812B data line can be connected directly to the ESP8266 without any level shifting! If you choose to go this route, power the Huzzah from its VBat terminal, so that the 3.7V will be regulated down to 3.3V to power the ESP8266. More details are available in Adafruit’s NeoPixel Uber Guide.

Since I want to be able to drive long strands of LEDs, I elected to go the 5V power with level shifter route. Also, I have lots of 5V power supplies laying around. There are many different ways to do level shifting, either passive or active. The WS2812B has tight timing requirements, and runs at 800KHz, so care has to be taken in order to avoid signal distortion. One of the most reliable methods is to use a 74AHCT125 level shifter IC. I decided to first try a simple diode and pullup resistor circuit (credit: RPi GPIO Interface Circuits):

The circuit is currently working flawlessly for me, driving my 5m long strand of 150 LEDs.


In order to send data to our WS2812Bs over WiFi, we need some sort of IP protocol. Art-Net is a royalty-free protocol, which sends DMX data embedded in UDP packets. I decided to go with Art-Net because it is an industry standard that is supported by a variety of Pro software, and Jinx! and Glediator can talk to it.


I will not go into how to set up Arduino to compile sketches for the ESP8266, as that is discussed elsewhere. To compile for the Huzzah, select it as the compile target from the Tools pulldown menu:

Tools -> Board -> Adafruit HUZZAH ESP8266

I created a sketch, which is a mashup of a few different projects from github. The code is in my github repo: WS2812ArtNet. I stripped the Adafruit NeoPixel library down to the bare metal, and added a captive portal for configuring the WiFi connection. Also, it supports a hardware pin to erase the WiFi settings. Configuration is done via a few defines in WS2812ArtNet.ino. See the #defines for PIXEL_CNT, PIN_DATA, PIN_LED, and PIN_FACTORY_RESET. At a minimum, PIXEL_CNT must be set to the number of LEDs in your strand.

PIN_DATA is used to select the pin that’s used to drive the data to the LED strand.

PIN_LED is used to select the a pin which blinks an LED every time an Art-Net packet is received. This makes it easy to tell if the board is receiving data. In addition, the LED is initially off at boot-up, and turns solid red when the ESP8266 connects successfully to a WiFi AP. By default, PIN_LED = 0, which makes it control the onboard red LED on the Huzzah.

PIN_FACTORY_RESET wipes out any saved settings and clears the EEPROM when it’s grounded for 2 sec.

To load the WS2812ArtNet sketch into the ESP8266, first press the GPIO0 and Reset buttons simultaneously, and then let go of the Reset button. The red LED will then glow dimly, indicating that the bootloader is active. Once the sketch is loaded, when the ESP8266 initially boots up, it will create a WiFi AP with SSID WS2812ArtNet_hh-h. Use a computer, phone, etc to connect to the AP. Upon connection, it should automatically present a captive portal for configuration:

If the captive portal doesn’t automatically launch, open a web browser, and point it to Tap on Configure WiFi, and the ESP8266 will automatically scan for available APs:

Tap the desired AP’s SSID, and type in the passphrase. Additionally, you can also choose a starting Art-Net universe, and configure a static IP. After you tap save, the ESP8266 will reboot. If it connects successfully to your AP, the onboard red LED will light. Then, the LED strand will go into the startup test sequence of lighting up red, green, and blue, and then turning off. Once Art-Net data is received, the LED still start blinking with every packet it receives.  If you have trouble during setup, you can see debug messages by opening the ESP8266’s serial port in a terminal set to 115200,N,8,1.


When configuring Jinx!/Glediator, select GRB as the pixel data format.


Prev: WS2812B LED (NeoPixel) Control: Part 1 – Serial Control via 8-bit ATmega (Arduino)

Mini Review: Linksys WRT1900AC

It infuriates me how so many WiFi routers are designed with inadequate cooling. I have a whole pile of routers that got flaky or crapped out after a few years due to overheating. The only ones that are still rock solid after years of continuous service are my WRT54Gs. My Linksys E4200 has been getting long in the tooth lately. On hot days, I need to blow a fan on it, and lately, even colder weather, it slows down to a crawl at random times and needs a reboot. I could try installing a big heatsink in it, but I thought maybe it was time for an upgrade to one of the fancier new technology routers. What most people don’t realize about the latest crop of router technology, such as AC3200, is that unless you upgrade your clients, you’re not going to get performance anywhere close to what these things can do. Most of the devices in my house are 2.4GHz 802.11n and can’t even handle MIMO, but smallnetbuilder had an article which showed that you can get a speed boost with 802.11n on a 802.11ac router. I figured I might as well future proof myself and look for a midrange AC router.


After lots of research on smallnetbuilder’s site, I settled on the Linksys WRT1900AC. This router, built by Belkin, is a nod to the venerable WRT54G, and is designed to be hacked with open source firmware. The specs are pretty good, even in the 2.4GHz band, which is often neglected these days, and I was particularly impressed with the speed of its NAS function, which vastly outperforms anything out there. It has a USB 3.0 port + a combo USB3.0/eSATA port on the back, and lightning fast storage performance. When I received it, I was impressed with the build quality. This thing is a beast! It looks like a WRT54G on steroids, and makes its predecessory look like a toy. Big & beefy and heavy. I specifically got the V1 because it has a built in cooling fan which kicks in only when necessary (which isn’t very frequent, due to its gigantic heatsinks). The later V2, also known as the WRT1200ACS, no longer has a fan. This is not going to be a full review of the WRT1900AC, but only a synopsis of my experiences trying to get decent 2.4GHz throughput out of it.

I really wanted to like the WRT1900AC. It is a thing of beauty, and I spent quite a few hours trying to tweak it, but to no avail. Despite the 90Mbps 2.4GHz LAN to WAN downlink throughput measured by smallnetbuilder, I was not able to get more than about 30Mbps downlink out of any of the devices in my house, even when sitting only a few feet from the WRT1900AC. This is only about half what I get out of my old E4200, which works as fast wirelessly as it does through Ethernet, maxing out at almost 60Mbps, which is the speed of my Time Warner cable service. No amount of tweaking over two days (about 6 hours of mucking with it) could speed up the 2.4GHz downlink performance. I scoured google for tweaks and even tried OpenWRT. I figured that I could figure out to get more speed out of it with OpenWRT’s tweakability, but it actually got slightly slower.

Although the speed with a very strong signal was only half as fast as my E4200, at the edges of my house, where the signal was weak, the WRT1900AC performed admirably, giving not only better throughput, but also being able to actually function at distances where the E4200 signal was completely dead. This left me in a dilemma, because the extended range is actually pretty useful to me. Also, for some reason, the storage performance came up quite short of what was tested by smallnetbuilder. I have a Seagate 2TB USB 3.0 drive, which is normally connected to a hacked Pogoplug E02 running Debian linux. The Pogoplug only supports USB 2.0, and doing a file copy across the network on Windows 8.1, I the maximum throughput I get is about 11MBps. Disappointingly, when attached directly to the USB 3.0 port on the WRT1900AC, the throughput topped out at a measly 4MBps. This was the last straw for me.

The 5GHz wireless performance on the other hand, was terrific. It easily saturated my 60Mbps downlink. But I can’t just switch to 5Ghz, because its range is too short in my house, and the signal drops out in some of my bedrooms. Also, not all of my devices support the 5GHz band. So, with a heavy heart, I decided to return the WRT1900AC. Just as I suspected, upgrading to the fancy 802.11ac router doesn’t necessarily help performance with 802.11n clients. In fact, looking at smallnetbuilder’s testing, lots of the latest and greatest routers put less emphasis on 2.4GHz performance, so if like me, you don’t have any 802.11ac clients, you should save your money and buy something cheaper. As for me, I’m going to try hacking a temperature-controlled fan into my old E4200, and see if that makes it more stable.