This repository contains software to load and start the Linux-Kernel on the Behringer X32, some userland tools and x32ctrl - the main logic of our custom firmware. This audio-mixing-console uses a Freescale/NXP i.MX253 Microcontroller with an ARM926EJ-S core that supports booting Linux.
Currently the Linux Kernel is running in Version 6.18 (LTS) with busybox:
x32ctrl is the new GUI and program that controls the individual boards and devices:
Since the beginning in May 2025 the UI has improved a bit and some of the original X32-functions are already implemented in OpenX32:
You can find more information in the two related Youtube-Videos:
A Youtube Short of the complete OpenX32 Alpha running on a X32 Rack:
Next to the underlaying Linux we are working on the audio-processing as well.
The Linux has control over most parts of the i.M253 main-controller:
- Linux-Kernel in Version 6.18 (LTS) starts to shell using 800x480 display framebuffer
- init-script for setting up the operating system
- MIDI-Input and -output is used as an additional serial-port-terminal (see pinout down below)
- Support of 100MBit ethernet network-support with DHCP
- Support of internal Realtime-Clock
- Support of USB-Host interface (HID-Keyboard, HID-Mouse, Mass-Storage-Devices, Joystick, Soundcard, etc.)
- Support of internal SD-Card to read MAC-Address and the general configuration
Most audio-functions are already supported:
- Configuration of FPGA (Xilinx Spartan 3A or Lattice ECP5) via internal SPI-interface
- Support of both AnalogDevices DSPs (ADSP-21371 SHARC DSPs) via internal SPI-interface
- Support of 1:1-routing for the available 112 inputs (32x XLR, 8x AUX, 32x Card, 40x DSP) to 112 outputs (16x XLR, 16x UltraNet, 8x AUX, 32x Card, 40x DSP)
- Support of UltraNet-Output
- Support of internal 8-channel analog input- and output-cards including headamp- and phantom-power-control
- Support of internal 8-channel AUX-AD/DA-Converter (CS42438 on older revisions, M8000 on newer revisions)
- Noisegate, 4-band EQ and compressor per channel is already working within the main-DSP
- Some more advanced audio-algorithms are already implemented in DSP2
- AES50 is working on Lattice-FPGA-versions. Receiving and sending audio and using the AUX-channel for headamp-control is working.
The hardware-surface is working, too:
- Support of booting from SD-Card and via USB using the original DCP-Bootloader
- Control of X32 surface (faders, buttons, LEDs, encoders) through x32ctrl-software
So the most important things (audio in/out, control-surface, display) are working already and more things are on the ToDo-list:
- In-Progress: Boot from barebox as a successor of U-Boot (U-Boot has ended the support of i.MX25 since a couple of years; barebox already boots OpenX32 from development sd-cards)
- Planned: ALSA Soundcard with I2S to main-FPGA (DeviceTree option "simple-audio-card" via SSI1 and AUDMUX is not initializing)
- Planned: GPIO support via libgpiod (at the moment libgpiod is not working and has no control over /dev/gpiochipX)
LVGL v9.5.0 is running on the X32 with a good performance (30 fps). So this will be a basis for this open-source Operating System:
I want to learn things about embedded systems and how they work. The X32 is a very powerful playground with lots of different controllers, nice faders and displays. So that's the only reason why I'm doing this :-)
Yes, here: https://discourse.openmixerproject.de
Checkout the most recent release from https://github.com/OpenMixerProject/OpenX32/releases and follow the instructions there. You only have to copy a couple of files onto an USB-thumbdrive and boot into Linux :)
You can login via SSH using the password "openx32" and the following command:
ssh root@IPADDRESS
root@192.168.0.153's password: openx32
____ __ ______ ____
/ __ \ \ \ / /___ \__ \
| | | |_ __ ___ _ __ \ V / __) | ) |
| | | | '_ \ / _ \ '_ \ > < |__ < / /
| |__| | |_) | __/ | | |/ . \ ___) / /_
\____/| .__/ \___|_| |_/_/ \_\____/____|
| | https://www.openx32.com
|_|
---------------------------------------------------
OpenX32 alpha5-29-g4cb74fa-dirty 18.04.2026
---------------------------------------------------
~ #
This system uses the most recent versions of the tools I could find: the bootloader u-Boot is used in Version 2020.10 as this is the last U-Boot supporting the i.MX25. Up to now Linux has still support for the i.MX25 and I selected v6.18, the most recent LTS-kernel.
So the repository uses other GitHub-repositories as submodules (u-Boot, Linux and pyATK). Please use the following command to checkout the main-repo together with submodules. To minimze the download-size and -time, we will clone the submodules separately:
git clone --depth 1 https://github.com/xn--nding-jua/OpenX32.git
cd openx32
./gitinitsubmodules.sh
Next to the sourcecode, your system needs to be setup correctly to compile the whole system: setup your debian-based system by calling:
./setup.sh
This script will install several dependencies to compile u-boot and the linux-kernel. After installing the packets, it will patch pyATK to run with recent versions of Python 3.11 and newer. It will also configure pyATK in a virtual python-environment.
Compile u-boot, Linux, busybox and the other tools simply by calling the script ./compile.sh:
./compile.sh
- compile.sh will copy some patched files into the submodules
- then it compiles the U-Boot-bootloader, the Linux kernel and other user-programs
- at the end all binaries are merged into a single binary file
- this binary file is finally compiled into a file that is compatible with the original bootloader of the X32 so that you can run the firmware from a USB-Thumbdrive directly
If you want to make this firmware permanent, rename the file from dcpxxx.run into dcpxxx.update and the firmware will be written on the internal SD-Card. The boot will be much faster compared to the USB-boot.
Within the software-folder several user-applications are placed:
- x32ctrl: this is the main-program responsible for the UI and the communication with hardware components
- x32sdconfig: this small software reads the original SD-card on boot and put general information about the board to the folder /etc/
There are some test- and debug-softwares in the "test"-folder:
- fpgaconfig: program to configure the Xilinx Spartan 3A FPGA using spidev2.0
- dspconfig: program to configure the two AnalogDevices 21371 SHARC DSP using spidev0.0 and spidev0.1
- spiread: program to test the communication to the DSPs
- uarttest: program to test communication with FPGA
The X32 devices before 2020 are using a Xilinx Spartan-3A X3CS1400 FPGA to route the audio between the individual ADCs, DACs, expansion card and digital connectors like AES50 and UltraNet. For the Spartan-3A we can use the free version of Xilinx ISE 14.7 as the most recent toolchain to synthesize logic for this FPGA:
Download ISE 14.7 from the Xilinx (AMD) website: https://www.xilinx.com/support/download/index.html/content/xilinx/en/downloadNav/vivado-design-tools/archive-ise.html. There are two options: a preinstalled linux virtual machine or the direct version. The virtual machine is working fine. If you want to use the direct version under Windows, here is a short manual as this needs some adjustments:
- Download the DVD image: https://www.xilinx.com/member/forms/download/xef.html?filename=Xilinx_ISE_DS_14.7_1015_1.tar
- Start the setup and install the software (the setup will take a loooong time). Between 93% and 95% the installation will hang: go into the taskmanager and kill the software "Webtalk32.exe" and "xwebtalk.exe" several times until the setup finishes (successfully!)
- Set the Windows-Environmental-Variable "XILINX_VC_CHECK_NOOP" to "1". Otherwise the software will complain about a non-installed VisualStudio Runtime 2008 even if it is installed correctly
- On modern Windows 10/11 ISE 14.7 will not start beyond the Splash-Screen due to the use of "SmartHeap" within the file "libPortability.dll". Download a hotfix from https://github.com/xn--nding-jua/OpenX32/raw/refs/heads/main/files/xilinx_ise_hotfix.zip, extract to C:\Xilinx\ and run the batch-file. The script will replace the 32-bit/64-bit versions of libPortability.dll.
- Start ISE 14.7, open the OpenX32 project and compile the logic of the main-schematic.
- On the left side of ISE 14.7 create a configuration file (bitstream)
- Copy main.bit to an USB-thumbdrive and load it either with "./fpgaconfig fpga.bit" or with the main-control-software "./x32ctrl fpga.bit"
An overview of the current FPGA-project can be found in the PDF-file of the top-schematic here: View Schematic as PDF.
The X32 uses two AnalogDevices 21371 SHARC DSPs for mixing. These devices are supported by the CrossCore EmbeddedStudio v2.12:
- Download CrossCore EmbeddedStudio v2.12.x: https://www.analog.com/en/resources/evaluation-hardware-and-software/software/adswt-cces.html#software-overview
- Request 90-day Trial-Software from Analog Devices
- Open the DSP-project in the folder "dsp"
- Use "Project -> Compile all..." to compile current project and "dsp1.ldr" will be generated
- copy "dsp1.ldr" to the USB-thumbdrive and load it either with "./dspconfig dsp1.ldr" or with the main-control-software "./x32ctrl fpga.bit dsp1.ldr"
DSP1 is the main-DSP receiving and sending all 40 audio-channels from and to the FPGA that is routing the audio to and from the individual sources. Within this first DSP the 32 + x main-channels are processed (noise-gate, multi-band-EQs, compressor, general mixing).
DSP2 is used for the more advanced audio-effects in the original system. This DSP is not used at the moment.
The MIDI-Ports are connected to the UART5 of the i.MX25. With a simple resistor and a RS232/USB-converter the MIDI-ports can be used for a serial-terminal with 115200 baud:
MIDI Out+ o---->---| MIDI GND o------| +5V o----->----o MIDI In+
Pin 4 ----- Pin 2 o Pin 4
| | Pin 5 (GND)
|4k7|
Pin 5 |___| Pin 5
MIDI OUT- o----<---|----->----o Pin 2 (RxD) Pin 3 (TxD) o-----<----o MIDI In-
see also: Article in our Discourse
- U-Boot in Version 2020.10 (https://github.com/u-boot/u-boot/tree/v2020.10)
- Linux in Version 6.18 (https://github.com/torvalds/linux/tree/v6.18)
- Busybox (https://git.busybox.net/busybox)
- LVGL in Version 9.5.0 (https://github.com/lvgl/lv_port_linux)
- Dropbear (https://github.com/mkj/dropbear)
- Framebuffer-VNC (https://github.com/ponty/framebuffer-vncserver)
- LibVNC (https://github.com/LibVNC/libvncserver)
- pyATK in Version 0.1.0 (https://github.com/hbock/pyatk)