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udpx Logo

udpx is a technology to transport data over WiFi to microcontrollers

What it can be used for

  1. Receive frame by frame animations generated by any UDP client application
  2. Receive over the air Video frames
  3. Be used as a Protocol base for a different mission like send on real time information from sensors

How to test this

Android App latest builds If you want to test this using Android just download and install the udpx app from Play store: udpx esp32

The udpx Android App is also open source. Feel free to explore and learn Cordova to make hybrid apps.

Configuring WiFi using Bluetooth

Starting with version 1.1 defined in lib/Config.h the firmware supports receiving configuration over Bluetooth Serial.

1.- Firmware boots, opens Bluetooth serial and waits for 9 seconds as default. Serial output:

UDPX 1.x
BTSerial active. Device name: udpx-3C71BF9D53DC_1234

2.- If in this time receives configuration it updates the SSID / Password and stores it on Preferences

3.- If it does not, after the wait time, tries to connect to the last known access point.

Serial output:

Start connection to AP_NAME
udpx-3C71BF9D53DC_1234.local is online
UDP Listening on:

If a fast start without wait is desired the best would be to add a hardware button, that only when pressed will wait for configuration.

First Pixel in the Led stripe or matrix will reflect the status

  1. BLUE Waiting for Bluetooth config
  2. GREEN Connected successfully, got IP
  3. RED Connection failed, will turn to 1.Waiting for config after 4 fails

udpx Android application steps:

1. Config Tab 2. Select your device and pair
step 1 step 2
3. Add your AP credentials and Send config 4. Go to antenna tab and click to set the IP
step 3 step 5
5. Done! Ready to receive UDP
step 6

Credits are due: All logic doing the Firmware part is from Bernd Giesecke, since I followed his great example on ESP32WiFIBLE Android app, to make this configurable per Bluetooth serial. I implemented in a way that both udpx Android and ESP32 WiFi BLE as a WiFi configuration mean are supported.

udpx Chrome App

In case you want to send test examples from a desktop computer try out our Chrome app in this branch. To install the it:

  1. chrome://extensions -> Enable developer mode
  2. Load unpacked extension and point to examples/chromeapp directory
  3. That's it, you can open it on: chrome://apps

Please note that this app will be discontinued and not supported anymore starting on February 2020 since the preferred way to test this is the Android app. Zlib is not supported on Chrome App and it's very hard to port, so we will leave the existing code just as a proof-of-concept on how to send UDP packets to udpx.


UDPX is a collaborative effort where a team of 3 have same access level to the repository:

Hendrik Putzek - Front end / Nodejs, VUE

Samuel Archibald - C++ / GO Api backend

Martin Fasani - Firmware and testing

Additional libraries

Pixels is a binary transport protocol. A way to send bytes to an ESP32 that are after arrival decoded and send to a RGB / RGBw Led strip.

S or "Little Stream" is an an embedded streaming library for embedded devices. Is simple data transport layer that is meant to be used in the udpx project that both is small as possible, and made for real-time applications, which has the ability to be compressed. Both protocols where developed by Samuel and are used by UDPX.


main Supports Brotli compression when the first byte is not 'p' (80), is the only branch that has BTSerial configuration

testing/testing-s Implementing here the Pixels+S Protocol (Aka "Little stream"

feature/tcp A TCP experiment since Martin had to do something for a client that wanted to use HTTP, interesting to see how fast is UDP compared to TCP, just left there for research reasons.

feature/json-v0.1 Only stored for historical reasons, it our first JSON + Brotli compressed protocol, that was tested and even though the limitations proved to be quite fast.

Branching model

Please adhere to following branching model when working in this repository. Not strictly, just to maintain a certain order and avoid loosing time.

master  → Main stable branch (clean/no debugging)
develop → Where features are merged only *after testing* (serial debug is ok)
feature/1 → Merged back in develop *only* after testing 
bug/1     → Merged back in develop

Please except of the existing feature branches do not leave stale branches unless there is a real need to have them. Branches that diverge from master/develop and are stale for weeks will be deleted.

Testing should pass when examples/test is open in the browser and two different ESP32 with RGB /RGBW stripe outputs match the expected results.

Experimental branches

feature/multichannel-chunk is using a experimental branch of pixels library that was recently merged in master. There the Neopixel out pins are defined like: const char pixelpin[] = { 19, 18 };

It's basically receiving 968 RGB pixels and sending the first chunk in channel 19 and the second 484 to channel 18. That sends them in parallel using 2 RMT channels, reducing the time serial communication is sent in a half and makes it gain framerate speed.
Please check Pixels library to understand how send the right headers.

Important configuration


Mandatory only if you don't use WIFI_BLE configuration: WIFI_SSID / WIFI_PASS

UDP_PORT defaults to 1234


The number of leds in the stripe or Led matrix, note that if you sent more than PIXELCOUNT it will simply not render it:

#define PIXELCOUNT 1000

The data pin(s) of the addressable leds:

const char pixelpin[] = { 19, 18 };

// Uncomment if we sent per chunks in different channels #define PIXELCHUNK 500 If this is set, then there are 2 header bytes (16 bit unsigned) that will signalize it too, and then first 500 pixels will go to pixelpin[0] and the rest will go to pixelpin[1]. Note that this is experimental and at the moment is only working for two chunks.

Uncommenting this line will enable RGBW mode sending 4 bytes per pixel. It should be commented if you use RGB:

#define RGBW

using RGB:

//#define RGBW 
// It defaults to this. We are using R,G,B on our led matrix part of the firmware since with White needs 4 bytes per pixel

Note: Switching between RGB to RGBW enforces you to update that line but also the Neopixel class features depending on the addressable leds you use (/lib/src/pixels/src/pixels.cpp) Please refer to the Neopixels wiki on the right way to do this correctly for your Led stripe.


This Firmware is limited by the MTU of the ESP32 that is 1470 bytes. If it receives a payload bigger than that the udp.onPacket callback will never take place. So in our experience we can send maximum about 1000 RGB pixels using PIX565 Zlib at a decent framerate.


This Firmware can work to stream pixel frame-per-frame animations to any Led stripe supported by the underlying library Neopixels. Any type of addresable LEDs should work if you select the right implementation in .libdeps/PIXELS Please make sure to check our Hardware buying guide if your are planning to stream video. Check the Neopixels documentation to select the right implementation to your LED Stripe.


2020-01 Implemented PIX565 Zlib compressed. The limit is now about 1000 Pixels using this protocol since it uses 2 bytes per pixel and Zlib compresses each frame, making it the fastest choice to send data so far

2019-12 Martin converted his Chrome example into an Android cordova hibryd application. It features WiFi configuration, multicast DNS discovery and picture/video streaming

2019-11 Martin worked out first a very raw Chrome App to send udp directly without middleware. This experiment lead to make a full pfledged Android Application in Dec. '19

2019-10 Implementing and testing S library

2019-09 Tests and fixes to achieve a stable RGB, RGBW version

2019-08 Samuel Archibald Made his first contribution and started a new protocol to get rid of JSON and send this even faster

2019-07 Decided to name the Firmware UDPX and make it open-source to let another developers join forces and use it for their own needs

2019-06 Started working with Front-end developer Hendrik Putzek to develop a firmware solution to transport a lot of frames per seconds from his Nodejs backend to a Led controller


This repository is licensed with a "CC Attribution-NonCommercial" License.

It contains code and examples that can be used and copied freely for artistic works and it can be also used for commercial projects provided you write as a line to explain how is going to be used and our license and credits are maintained. We put really a lot of time and effort building this Firmware and we would like to give proffesional support to integrate it in the future.

Companion Firmware

Remora Listens short UDP commands and triggers fast animations in ESP32/ESP8266. It supports udpx protocol (non compressed). So it can receive and render up to 484 RGB pixels as an animation frame.


udpx is a technology to transport data over WiFi to microcontrollers, supports Zlib decompression




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