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https://github.com/hzeller/rpi-matrix-pixelpusher

PixelPusher protocol for LED matrix.
https://github.com/hzeller/rpi-matrix-pixelpusher

Last synced: 17 days ago
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PixelPusher protocol for LED matrix.

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README 

        
Controlling RGB LED display on Raspberry Pi GPIO via PixelPusher protocol

=========================================================================



[![Example video][vid]](http://youtu.be/ZglGuMaKvpY)



Code is (c) Henner Zeller ,

license: GNU General Public License, Version 3.0



For details of the RGB Matrix library used and how to connect,

see the github over at [Raspberry Pi RGB Matrix][rgb-matrix-lib].



Compiling

---------

Clone with `--recursive` to get the RGB matrix submodule when cloning

this repository:



    git clone --recursive https://github.com/hzeller/rpi-matrix-pixelpusher.git



(If you did a `git pull` to get the latest state, also make sure to get the latest matrix code:

type `git submodule update`).



Wiring

------

For wiring, please have a look at the [library documentation][rgb-matrix-lib].



You can choose the wiring you are using with the option `--led-gpio-mapping`

on the command line. E.g. if you are connected to an Adafruit HAT, then it is

`--led-gpio-mapping=adafruit-hat` or `--led-gpio-mapping=adafruit-hat-pwm`

depending on if you did the PWM modification (which you absolutely should to

reduce flicker.



Running

-------

Simply run the program as root (which is needed to access the GPIO pins). It

will drop its privileges once it has set up the hardware.



     $ make

     $ sudo ./pixel-push



These are the available options



```

usage: ./pixel-push 

Options:

        -l            : Switch on logarithmic response (default: off)

        -i     : network interface, such as eth0, wlan0. Default eth0

        -G     : PixelPusher group (default: 0)

        -C  : PixelPusher controller (default: 0)

        -a : if used with artnet bridge. Default 0,0

        -u  : Max UDP data/packet (default 1460)

                        Best use the maximum that works with your network (up to 65507).

        -d            : Same as --led-daemon. Use this when starting in init scripts.

        --led-gpio-mapping= : Name of GPIO mapping used. Default "regular"

        --led-rows=         : Panel rows. Typically 8, 16, 32 or 64. (Default: 32).

        --led-cols=         : Panel columns. Typically 32 or 64. (Default: 32).

        --led-chain=     : Number of daisy-chained panels. (Default: 1).

        --led-parallel= : Parallel chains. range=1..3 (Default: 1).

        --led-multiplexing=<0..6> : Mux type: 0=direct; 1=Stripe; 2=Checkered; 3=Spiral; 4=ZStripe; 5=ZnMirrorZStripe; 6=coreman (Default: 0)

        --led-pixel-mapper        : Semicolon-separated list of pixel-mappers to arrange pixels.

                                    Optional params after a colon e.g. "U-mapper;Rotate:90"

                                    Available: "Rotate", "U-mapper". Default: ""

        --led-pwm-bits=<1..11>    : PWM bits (Default: 11).

        --led-brightness=: Brightness in percent (Default: 100).

        --led-scan-mode=<0..1>    : 0 = progressive; 1 = interlaced (Default: 0).

        --led-row-addr-type=<0..2>: 0 = default; 1 = AB-addressed panels; 2 = direct row select(Default: 0).

        --led-show-refresh        : Show refresh rate.

        --led-inverse             : Switch if your matrix has inverse colors on.

        --led-rgb-sequence        : Switch if your matrix has led colors swapped (Default: "RGB")

        --led-pwm-lsb-nanoseconds : PWM Nanoseconds for LSB (Default: 130)

        --led-no-hardware-pulse   : Don't use hardware pin-pulse generation.

        --led-slowdown-gpio=<0..2>: Slowdown GPIO. Needed for faster Pis/slower panels (Default: 1).

        --led-daemon              : Make the process run in the background as daemon.

        --led-no-drop-privs       : Don't drop privileges from 'root' after initializing the hardware.

```



This will advertise itself as a

PixelPusher  device

on the network. Number of 'strips' will be number of rows, so 16 or 32 multiplied by the parallel panels (1 .. 3).



#### Network UDP packet size

The `-u` parameter specifies the size of the allowed UDP packets. Some network

switches (and the original PixelPusher hardware) don't like large packets

so the default is a conservative 1460 here.



But since we have a lot of pixels, using the highest number possible is

desirable so ideally we can transmit a full frame-buffer with one packet (use

something like 65507 here):



```

     sudo ./pixel-push -u 65507

```



Even if the network supports it, sometimes sending devices limit the packet size (e.g. iOS, 8192 seems to be the limit of packets to send; important if you use

LED labs softare) so we have to change:



```

     sudo ./pixel-push -u 8192

```



Controlling Software

--------------------

You can control these for instance with the Processing framework

. The processing framework already has a contrib

library section that allows you to select PixelPusher supporting libs.



Another software supporting the PixelPusher support is L.E.D. Lab http://www.ledlabs.co/



Artnet / sACN

-------------

If you use the [artnet bridge][artnet], you can specify the artnet-universe and the

artnet-channel with the `-a` option:



    sudo ./pixel-push -a1,1



Larger displays

---------------



Generally, if you want larger displays, it is suggested to first use the

feature of connecting multiple parallel chains to one Raspberry Pi; the [adapter]

in the underlying project provides three outputs.



If you have the Adafruit HAT, then you only can do one chain, but you can

arrange them in a sideways 'U' shape to get a more square display. This

then can be mapped correctly with `--led-pixel-mapper="U-mapper"`.



Here are four panels arranged in a square on a single

connector, typically something you might want do do if you want a 64x64

arrangement of four 32x32 displays on an Adafruit HAT (which only provides one

chain):



```

   [<][<]  }--- Pi connector #1 (looking from the front)

   [>][>]

```



(`--led-pixel-mapper="U-mapper" --led-chain=4 --led-parallel=1`).



This is how it looks wired up from the back:



![Chaining multiple displays][matrix64]



How about 6 panels ?

```

   [<][<][<]  }--- Pi connector #1

   [>][>][>]

```



(`--led-pixel-mapper="U-mapper" --led-chain=6 --led-parallel=1`).



This even works if you have multiple parallel chains. Here is an arrangement

with two chains with 8 panels each:



```

   [<][<][<][<]  }--- Pi connector #1

   [>][>][>][>]

   [<][<][<][<]  }--- Pi connector #2

   [>][>][>][>]

```



(`--led-pixel-mapper="U-mapper" --led-chain=8 --led-parallel=2`).



The `--led-pixel-mapper="U-mapper"` option essentially gives you half the

width of a panel, but double the height.



If you have a Raspberry Pi 2 or later consider assembling a display using

parallel chains, for instance using the [adapter] that is provided in the

RGB matrix project



[rgb-matrix-lib]: https://github.com/hzeller/rpi-rgb-led-matrix

[matrix64]: ./img/chained-64x64.jpg

[vid]: ./img/pp-vid.jpg

[artnet]: http://heroicrobotics.boards.net/thread/39/artnet-support-sacn

[adapter]: https://github.com/hzeller/rpi-rgb-led-matrix/tree/master/adapter/active-3