OLA developer info

Or LLA code documentation Link to the LLA main page.

Drivers and platforms

LLA compiles on Linux and Mac and probably also Windows, but not all drivers work everywhere (yet). Here the status can be listed.

Supported Devices/Protocols:

Driver	Linux	Mac OS X	Windows
ArtNet	Linux=Yes	??	??
ShowNet	Linux=Yes	??	??
ESP Net	Linux=Yes	??	??
Sandnet	Linux=Yes	??	??
DMX USB Pro	Linux=Yes	??	No
Open DMX USB 1)	Linux=Yes	??	No
DMX 4 Linux	Linux=Yes	??	No
StageProfi	Linux=Yes	??	No
Pathport	Linux=in testing	??	No
E1.31 / ACN	Linux=development started	??	No

Note 1): Support through the Linux kernel module from Erwin Rol, as detailed in LLA, OpenDMX USB and Q Light Controller Tutorial.

Unsupported USB devices:

• Peperoni Rodin1 (but this is supported directly by QLC)
• Peperoni USBDMX21
• Anyma uDMX
• USB DMX from usbdmx.com
• Sandsys UMX2
• Sandsys UMX4
• Velleman K8062 (no developer info available?)

Suggestions for content:

• What is the structure of the plugins?

I'll use plugin to refer to the entire module (Plugin, Devices & Ports), and Plugin to refer to the class that inherits from Plugin.

Plugins create and register Devices, which each consist of 0 or more Ports. A Plugin generally does a bit of work when it starts, then leaves all work to the individual Devices and Ports.

This is the general lifecycle of a Plugin object:

The create() function is called with a pointer to a PluginAdaptor, this returns a new instance of the Plugin.
  Obviously the constructor is called - use this to init variables but any real work should be done later.
Plugin.start() is called, which calls start_hook()
  Within start_hook, the Plugin should create Devices and register them by calling plugin_adaptor->register_device(device).
...
At any time we may call get_id(), get_name(), get_desc() on the Plugin.
...
Plugin->stop() is called, which calls stop_hook(). 
  The Plugin should unregister any devices created in start_hook()
The destroy() function is called. This should delete the Plugin created in create().

• So how do devices / ports work?

• Here's an example of how dmx data is received from the UsbPro Device.

The UsbProDevice will have been registered using plugin_adaptor->register_fd(). When input becomes available the following sequence happens:

 device->action() // signals the device that new data is available
   widget->recv() // tells the widget to read more data
     widget->do_recv() // reads the data from the fd
       widget->handle_cos() // handles the change-of-state message from the widget
         device->new_dmx() // signal the device that new dmx data has arrived 
          port->dmx_changed() // signal the port that new dmx data has arrived
            port->read()
              device->get_dmx()
               widget->get_dmx()

Of course, the plugins authors are free to implement this however they like.

• I have difficulties to track the flow of data from it is fetched from the USB Pro until it is printed to the console by the app lla_usbpro. Some diagrams over the structure and data flow diagrams, or text that gives a good overview would be nice

Config messages are handled a little differently for two reasons:

- The configure() method in a plugin has to return a response immediately. We don't want to block because we'll delay all lla processing. The new RPC subsystem removes this limitation.
- Sending a PARAMETER_REQUEST to the widget doesn't generate a response immediately (in fact it may not generate one at all).

To work around this, we send a parameter_request when we start the device, and then anytime we set parameters. In the meantime we store the parameters in the widget object and return those. The sequence looks like:

 device->configure()
   device->config_get_params()
     widget->get_parms()

• What is the interface between the LLA core and LLA plugins?

 See above and the files plugin.h, device.h and port.h. Within plugins, you'll have access to a PluginAdaptor which can register/unregister file descriptors, loop functions, timeouts and devices.

• What is the interface between the LLA core and other apps/clients to LLA like QLC?

• What is it with the hidden web server?

 That's coming in the next version. It's not checked in yet.

How is functionality split between the usbpro plugin and the example program?

Ideas for easy configuration

For some users, it will be useful to have a "auto-connect" feature. When a attached device is discovered (either when LLA i started or when a new device is attached), the user could be asked if the available ports (input as well as output) should be patched to the lowest available universes.

• Enable auto-connect ( OFF|connect whatever comes first|connect by stored patch layout)
• Save a given combination of devices (just by type or with unique ID's from serial numbers, USB device ID's etc)

Which devices cannot be autodetected?

Ideas for QLC integration

Here is room for YOUR writing :-)

LLA plugin for the "USB Pro"

label=3 response

• 1. data byte= Firmware version LSB. Valid range is 0 to 255.
• 2. data byte=Firmware version MSB. Valid range is 0 to 255.
• 3. data byte=DMX output break time in 10.67 microsecond units. range=[9-127] (96.03 - 1355.09 micro seconds)
• 4. data byte=DMX output Mark After Break time in 10.67 microsecond units. range=[1-127] (10.67 - 1355.09 micro seconds)
• 5. data byte=DMX output rate in packets per second. range=[1-40]
• x. data byte= some user configuration of the requested size