ACAB Setup Instructions

The goal of this page is to gather all information needed to set up an ACAB installation from the ground up.

The currently used hardware can be found at

The board and schematic used for the ACAB installations are board/buslamp.{brd,sch} and are designed with EAGLE.

The hardware uses RS484 to signal data to the lamps and a 24 V to 28 V supply voltage. Both the RS484 signal and the supply voltage are carried on a single cable. To keep the cost down standard Cat 5 network cables are used.

To communicate with the host computer, the RS484 interface has to be adapted to another interface. The device described by board/ub.{brd,sch}. It is intended to be used with our IPv6 home automation project, but can also be used to act as an USB to RS485 bridge.

With standard 2 m long Cat. 5 cables, up to 8 lamps can be put into series. With more lamps or longer cables, the power loss in the cables is to large and the system starts to get unreliable. With shorter cables (e.g. 0.5 m), it should be possible to put more lamps into series.

For best utilization and robustness, power should not be injected from one side of a string. It should rather be injected from the middle of a string. This technique cancels out the voltage drops on the ground line (which helps the RS485 bus to stay in its operational limits) and gives better utilization of a single power supply.

Power can be injected by using the same circuit boards as the lamps. Only the two jacks, the jumper and the two screw terminals need to be populated. The board can now be used to inject power into the system. When using multiple power supplies in a single line, the jumper, bridging the 24 V power supply from one jack to the other, needs to be removed to decouple the power supplies.

RS485 Bridge <-> Lamp 1 <-> ... <-> Lamp 8 <--   --> Lamp 9 <-> ... <-> Lamp 16 <-|-> Lamp 17 <-> ... <-> Lamp 24 <--   --> Lamp 25 <-> ... <-> Lamp 32
                                              \ /                                 |                                  \ /
                                               |                                  |                                   |
                                       24 V Power Supply                 24 V Supply Wires Cut                24 V Power Supply

Each installation poses its own difficulties and tasks. The following general rules should give some guidance:

  1. Test all parts of the system before going to an installation
  2. It takes longer to set up the installation as expected.
  3. During the installation, start testing parts of it as early as possible. Ideally you prepare some test animations to test single parts of the installation, while it gets built up. These tests should at least test each channel individually per lamp. The system must also still be reliable with all channels of all lamps turned on at the same time.
  4. Think about people (unintentionally) running into your installation. Will they get hurt? Will your installation survive?

When using translucent plastic boxes from IKEA the following special steps apply:

Box Size: 61cm x 41cm
Box Height:35cm

Height of 10 stacked boxes (in transport mode): 48cm

Weight (with cover, without electronics): 1550g
Weight (withoub cover, without electronics): 1100g

Available Boxes with covers: ca. 110

12-15kg network cables

one power supply: 1kg
one lamp: 100 gr

The ACAB daemon receives a stream of animation data via UDP and forwards it to the ACAB installation. It can control multiple RS485 bridges, connected to multiple sets of ACAB lamps.

The daemon can be found at

It is located inside the server/ directory. There are two submodules: The acabslserver and the acabslrouter.

Animation Streams

TODO: explain the UDP packet format


The acabslrouter accepts a stream of animation data and forwards the data to an acabslserver instance which controls a particular part of the installation. This makes it possible
to control an installation with more than one wall of lamps. The acabslrouter also supports different priorities and timeouts for different streams. This can be used to display an idle animation when
no other animation is active or overlay an active animation with some interactive game.


Currently, the acabslrouter is configured directly inside its source code.

The configuration consists of a list of entries like the following:

{'host': 'localhost', 'port': 5000, 'simhost': 'localhost', 'simport': 4000, 'startx': 0, 'starty': 0, 'sizex': 16, 'sizey': 6}

Each of these entries specifies the properties of a single wall. It contains the following fields:

  • host The host where the acabslserver for this wall can be reached.
  • port The port on which the acabslserver is listening
  • simhost The host where the data stream should be redirected if the system is simulated
  • simhost The port where the simulator is listening
  • startx The logical start of the matrix in the data stream. Set this to 0 if you only have a single matrix. Set this to a multiple of the horizontal size of the used matrices.
  • starty Similar to the startx fiels, but for the vertical direction.
  • sizex The physical size of the matrix in the horizontal direction
  • sizey The physical size of the matrix in the vertial direction

The configuration also accepts a list of ports where incoming streams are accepted as well as a priority and timeout for each port.

If a port did not receive data for longer than the timeout, the acabslrouter switched to a data stream on a port with a lower priority

The acabslrouter always chooses the data stream on the port with the highest priority which did not experience a timeout. A timeout occurs when a port does not receive a valid telegram for longer then the period specified in the timeout field:

 {'port': 6000, 'priority': 0, 'timeout': 1}
  • port The port to listen on.
  • priority The priority of this port. Higher values have higher priority.
  • timeout The timeout in seconds of this port.

To start the server, you can specify one of the following options: 'simulation' and 'nosimulation'.


python nosimulation
  • nosimulation Do not send the stream data to a simulation server. Use this setting to drive a real matrix without also displaying its contents on a monitoring simulation server,
  • simulation Do not send the stream to a real matrix. Use this setting if you just want to test the router without hardware.

If you do not specify any of these options, the data will be sent to a real matrix as well as to a simulator.


The server accepts a stream of animation data via UDP. If the stream modifies the state of a pixel which is controlled by the acabslserver, the server will translate the command to a command used by the lamps and will pass it to the appropriate RS484 bridge, associated with this pixel.

The acabslserver accepts a configuration file which defines the location of the different lamps in the matrix controlled by the server as well as the configuration of the RS484 bridges.

auto configuration via webcam

based on

  • on acabsl server run server/ -f <config file name>
    • check if it correctly detected the number of interfaces
  • Make sure your webcam has no “automatic white balance”, or it is turned off.
    • internal webcams often can not turn it off, use an external webcam in this case.
  • locally run server/
    • command line -h acab2 for acabsl server name
    • command line -i 2,3 which interfaces to use on the server
    • command line -c 1 for second camera (if you have internal webcam)
    • optional: add command line –diff for “differential mode” when default mode doesn't work
  • make sure whole wall is inside camera, and not too much around it
  • make sure wall is approximately aligned with picture borders
  • move the pixel slider slowly until any pixel is lit
  • check if pixel is well-recognized, otherwise fiddle with H+ and H- sliders
  • move the run slider to 1
  • watch the script run. It will display the detected config/grid when done.
    • Optionally drag & drop some of the dots to make the grid-finder algorithm work.
  • If the config looks good you are done. The config has already been sent to the server.
  • kill, and start server/ server/
manual configuration

To generate this configuration file, a tool is available: server/


It automatically detects all connected RS484 bridges and starts to locate the different lamps in the matrix. It does this by first determining
to which interface a specific lamp is connected and then locating the specific lamp on this bridge.

The script first asks a few questions: The size of the matrix as well as the range of the used addresses.
As addresses below 10 are reserved for special purposes it is set as the default value for the lower range of the address space.
If you know what the highest address of the used lamps is, you can enter this as the upper limit of the address space, to reduce the time needed to find a specific lamp.

The scripts will ask you to specify a coordinate. It will then try to determine the address of the lamp at this location. It does this by blinking the different lamps in different colors. It will then ask you what the lamp at the specified location is doing. After some time it will find the correct address and only blink the found lamp with a white color.

Every time, a new lamp is found, the configuration file is written. You can abort the script at any time. You can also always start the process for an already configured location if you made a mistake.

After every lamp has been found, you can terminate the script. It will have written a configuration file to the filename specified as its argument.

The configuration file will contain the following line:

UDP_PORT = 5004

This is the port on which the acabslserver will listen. Please change this port if you have multiple servers running on the same machine or if your acabslrouter configuration
expects a different port.


Sound controlled


The software for the RS485 bridge can be found inside the rs485bridge/ directory. It translates frames from a normal serial connection to
the RS485 bus used by the system. When used with the device mentioned above, it can be used to connect an ACAB installation to a PC.

To program the RS485 bridge:

cd rs485bridge
make fuse
make program

The bootloader for the boards can be found at inside the ubloader/ directory.

The bootloader is used to update the firmware of the lamps while they are inside an installation and therefore inaccessible.
It consists of a small bootloader program, running on the lamps, and a set of Python and bash scripts to upload new firmware to the lamps.

The bootloader can upload new firmware to a lamp and program arbitrary parts of the EEPROM. To single out a lamp on the bus and only program a single one,
the bootloader can be used to compare an arbitrary section of the EEPROM to data transmitted via the bus.

The scripts use this feature to select a single lamp after all lamps performed a power on reset.

To flash lamps which have not yet a unique EEPROM content, the bootloader can be forced to consider the lamp selected.


./select-m644p <ADDRESS>

Starts to send the select command to the bus. If a lamp with a bootloader reboots and has the corresponding id programmed,
it will get selected. If no id is supplied any lamp on the bus will get selected. After a lamp got selected, the scripts returns.
If a lamp got selected, it turns green. If a lamp is not selected it stays red.

<ADDRESS> must be a hexadecimal number greater 0x10. Addresses smaller than 0x10 are used for
multicast addressing. Example: ./select-m644p 5B

./set-m644p <ADDRESS>

Sets the address of the selected lamp to <ADDRESS>. See ./select-m644p on specifications for <ADDRESS>

./flash-m644p <BINARY>

Loads the binary at <BINARY> directory and sends it to the lamp.


Starts the program inside the selected lamp. This command always return with a timeout.


If a new lamp needs to be configured and flashed

Flash the bootloader to the lamp:

cd ubloader
make fuse
make program

Compile the moodlamp firmware:

cd moodlamp-bus

Connect the RS485 bridge with the lamp and apply 24V power to the lamp. The lamp starts to light up red.

cd ubloader
./set-m644p <ADDRESS>   #use a different address for each lamp!
./flash-m644p ../moodlamp-bus/fnordlicht.bin
If a single lamp needs to be flashed with new firmware

Compile the moodlamp firmware:

cd moodlamp-bus

Start to select any lamp:

cd ubloader

Connect the RS485 bridge to the lamp and apply 24V power to the lamp. The lamp turns green.

./flash-m644p ../moodlamp-bus/fnordlicht.bin

The lamps should now boot the new firmware.

If a lamp is inside an installation and needs new firmware

Compile the moodlamp firmware:

cd moodlamp-bus

Start to select the specific lamp

cd ubloader
./select-m644p <ADDRESS>  #Example: ./select-m644p 5A

Toggle the power of all lamps, The specified lamp turns green and the script returns.

Flash the new firmare:

./flash-m644p ../moodlamp-bus/fnordlicht.bin
  • acab/setup.txt
  • Last modified: 2022/03/10 18:26
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