A I R E N C E - U S B M a n u a l P a g e 33
USB channel controls
Furthermore, the fader start, on and cue signals of the four available USB channels in the Airence mixer could also be used to
trigger or control any software application. In combination with the control module the Airence mixer provides a flexible all-in-
one solution to manage and control specific play out systems.
Figure 2. USB Channel Controls
How does it work?
Communication Interface
The present USB bus on the Airence mixer is used as the interface to transfer all the control signals to the PC. In order to keep
things simple the HID (Human Interface Device) protocol is used for communication between the Airence mixer and PC.
On top of the HID protocol there is specific control protocol developed at D&R which is discussed in depth in the chapter
“Airence USB HID Control Protocol” for those who wants to go “deeper”.
Update rate
When a state change of a control signal (switch, fader, encoder) occurs, the current state of all the controls are transmitted to
the PC. Such a state change of a control signal is called an event. The state of a switch can be
pressed
or
released
. In case of an
encoder the additional states besides the
pressed
and
released
ones when pushing the encoder (switch function), are
increments
or
decrements
when turning.