Generic PixelPusher Server implementation

This implements the PixelPusher protocol similar to the PixelPusher devices by Heroic Robotics.

This code attempts to be compatible with a basic subset of that protocol.

Originally implemented in my rpi-matrix-pixelpusher repository, but separately provided here for clearer API boundaries and simpler re-use.

License

(c) 2013 Henner Zeller [email protected].

This is free software, licensed with the GNU General Public License, Version 3.0

Please read and understand the license to learn which freedoms it provides to you and users of the code you link it with.

Using this Library

This is a library, which you can use in your own code. If you are not a programmer, this is not for you (in that case might more be interested in solutions such as the RGB Matrix or the Spixels PixelPusher implementation).

All you have to do, is to include include/pp-server.h, implement your output device, which needs to extend pp::OutputDevice, then call pp::StartPixelPusherServer().

class MyPixelOutputDevice : public pp::OutputDevice {
   // ... implement necessary methods are required by pp::OutputDevice,
   // such as SetPixel() (see include/pp-serve.h for details).
};

int main() {
   MyPixelOutputDevice pixel_output_device;   // Your implementation.

   pp::PPOptions options;
   options.network_interface = "wlan0";
   if (!pp::RunPixelPusherServer(options, &pixel_output_device))
       return 1;

   // -- Now, the PixelPusherServer is running in the background.
   for (;;) sleep(MAX_INT);  // do whatever else. Or just wait forever.

   pp::ShutdownPixelPusherServer();
   return 0;
}

.. then link the library found in lib (Makefile in there, simply run 'make' in that directory). Typically, you'd provide the path to the library in your compilation call like so:

g++ my-pp-server.cc -o my-pp-server -Llib -lpixel-push-server

As a general suggestion to use it in your own code is to use include this library as a sub-module in git, e.g. here checking it out in a sub-directory pp-server in your project:

     git submodule add https://github.com/hzeller/pixelpusher-server pp-server

For an example how to do this, check out the RGBMatrix implementation using this library as a sub-module and how it is referenced in the Makefile.

Network UDP packet size

The PPOptions::udp_packet_size 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 if 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). This works well when sending data from an application on your regular computer e.g. using processing.

Even if the network supports it, sometimes sending devices limit the packet size (e.g. iOS, 8192 Bytes seems to be the limit of packets to send; important if you use LED labs softare) so in that case, we have to use 8192 as udp_packet_size.

Controlling Software

You can control these for instance with the Processing framework http://processing.org/. 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 Heroic Robotics artnet bridge, you can specify the artnet-universe and the artnet-channel in the pp::PPOptions struct.