Since we are nowadays working from home, it makes not really sense anymore to have a ‘Build Status Light’ with a ‘Broken Build Siren’ at the office. I wanted to do something fun and created a personal ‘Build Light’ for my team members.  The device is build using some cheap components and is very easy to create. The device is subscribed to MQTT topics which provides the status of multiple CI/CD Pipelines or a single CI/CD pipeline on all leds at once.

I replaced the WiFiManager library with IotWebConf library which has an always available configuration page.

Below the README.MD from the Github Repository which is always up-to-date.

1. MQTT_NeoPixel_Status_Multiple_Improved

Drive Neopixel LEDs based on MQTT Messages.

Github Repository: MQTT_NeoPixel_Status_Multiple_Improved


Download: Prebuild firmware binaries

Control each individual LED or all leds together of a NeoPixel LedRing (or ledstrip) by publishing a color 'green, red, yellow, etc' to a specific MQTT Topic per Led.

You could use it to indicate the build status of one or multiple CI/CD build pipeline(s)

Flash an updated firmware or change the configuration directly from your browser.

The current version (v1.5) requires IoTWebConf v3.1.0. The code is not compatible with an older version.

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2. Hardware

2.1. Required Components

  • Wemos D1 Mini 4Mb (ESP8266)
  • NeoPixel 12 pixel LED Ring from AliExpress (has a different size than the original from Adafruit)
  • 1000uF Capacitor
  • 470 Ohm resistor
  • 3D Printer, solder iron and a couple of wires.

The case can be 3D printed using PLA. The STL and Fusion360 files can be found here:

The source code for the the recent version:

2.2. Pinout & wiring

  • Connect 5V of LedRing with 5V on Wemos
  • Connect GND of LedRing with GND on Wemos
  • Connect DI (data in) of LedRing via the 470 ohm resistor with D2 on Wemos (GPIO4)
  • Put the 1000uF capacitor in parallel with the LedRing (so the + on 5v and – on the GND. An Electrolytic capacitor has a + and – pin so pay attention!
  • connect D1 to GND during startup to force AP mode with initial password An additional power supply is not required (for 12 Pixel ledring) as long as you don’t turn on all leds on white full power.

3. Device Setup

3.1. Flashing firmware

Flashing the firmware can be done using PlatformIO which is an OpenSource Embedded development platform with a great plugin for Visual Studio Code. Install PlatformIO in Visual studio Code and clone this repository to a local folder. The repository is setup for use with PlatformIO and will take care of required libraries and such.

The platformio.ini is setup for both Wemos D1-MINI (4Mb) and D1-MINI-PRO (16Mb).

Never used PlatformIO? Check this page: PlatformIO - How to flash firmware

3.2. Initial setup of the device

Power on the device and connect your laptop to the wireless access point "NeoPxLight" with password "password". Wait a little for a 'captive portal' to show. If it does not show, visit where you can configure the device. Be aware that you have to disconnect from this accesspoint after configuration before the device connects to your home WiFi. It also takes about 30 seconds after boot before the device switches to WiFi. In these first 30 seconds you can connect to "NeoPxLight" if you need to.

The field AP password sets you password when you want to access the configuration portal AND it is indeed the new accesspoint password. Do not forget this password! If you need to reset it, you have to use a wire. Since v1.3 of the firmware you can force the accesspoint mode to remain active using the initial password by connecting pin D1 to GND at startup. Then you can connect to the '"NeoPxLight"' AP with '"password"' and configure a new password.

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3.2.1. WiFi & MQTT

Setup the WiFi by typing your SSID and provide your MQTT details. As topic you use something like: some/thing/# (read more below). A unique MQTT ClientID is created based on the ChipID. Be aware of case sensitive usernames and passwords and auto correction messing this up 🙂

3.2.2. Led offset

To align the first led to the position where you want to see the first led, you can provide the led offset. While you are connected to the configuration page, the device shows the 'real' first LED in red (or green when offset = 0). Now count how many LEDs (clockwise) further you want to position the first LED and enter that value as the offset. After applying the settings you will see the Green LED indicating what will be used as LED 1 for 5 seconds. As long as you have the configuration page open this green and red led will be displayed. Close the webpage (and reset the device) to get it running.

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3.2.3. Led brightness

You can set the brightness of the leds to a value between 5 and 200. (if you really want and your powersupply can handle it you could change the max to 255 in the source code). Each LED Pixel is a Red, Green and Blue led. Each drawing up to 20 mA. So a bright white pixel draws 3 x 20 mA = 60 mA. All 12 LED Pixels on full white means a current draw of 720 mA. The Wemos D1 onboard power regulator can handle max 500 mA. So with 200 instead of 255 as max and not using white pixels it should be fine.

3.2.4. Single Status

When you enable 'single status' it means that the whole ledring shows only the status of 1 MQTT topic (some/thing/1). You can provide a number in the Single Status Number field if you want another MQTT topic than some/thing/1. If you deselect the 'single status', each led will represent a seperate topic (some/thing/1 up to some/thing/12)

3.2.5. Single Status number

You are subscribed to a MQTT Topic like: some/thing/#. The idea is that # is a number of e.g. a build pipeline, a status of something, etc. When you enable the 'single status', then all the leds represent the status of one number (#). The Single Status number on the configuration page is that number. So, let say you have 12 buildpipelines. some/thing/1 to some/thing/12. At a certain moment you want to keep monitoring the status of only one pipeline, lets say pipeline 5. You then enable the single status checkbox and you enter 5 in the Single status number field.

3.3. Change configuration

Browse to the IP of your device and login with admin and the AP Password which you have initially set. It will show the current setting and a link to the configuration page. Once you visit this page the device will show the led offset indicator when not in single status mode.

3.4. OTA Firmware update

You can update the firmware through the configuration page.

When you 'Build' the application in PlatformIO, you can find the firmware.bin file in a hidden directory .pio in your project folder (/MQTT_NeoPixel_Status_Multiple/.pio/build/d1_mini/).

You can also download a firmware binary ready to be uploaded from: Prebuild firmware binaries.

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4. Controlling the LED's

4.1. MQTT Topic

Subscribe the device to a topic like: some/thing/#

It is very important to add the /# at the end. This way the device receives all messages of all topics below some/thing. Now each led will respond to its own topic:

Led 1 --> some/thing/1

Led 2 --> some/thing/2

Led 3 --> some/thing/3


Led 12 --> some/thing/12

4.2. MQTT Payload

To set the color of a LED you send a specific payload to the MQTT Topic of that LED. It is case sensitive. You can choose to have a static LED or blinking LED in the multiple status mode. In single status mode the whole ledring has either one color or in case of blink, the leds are chasing each other.

  • green
  • greenblink
  • red
  • redblink
  • yellow
  • yellowblink
  • purple
  • purpleblink
  • blue
  • blueblink
  • orange
  • orangeblink
  • white (since firmware v1.5)
  • whiteblink (since firmware v1.5)
  • off

So, to make LED 5 Blinking purple you send: purpleblink to topic: some/thing/5

4.3. NodeRed

I use NodeRed to listen to all kind of statusses of Domotica or IoT sensors and then act upon that status by sending MQTT Messages to the device.