What it does...
There are several incarnations of xAP display. At it's simplest, it is just a question of connecting an off-the-shelf serial LCD or VFD display to suitable Windows or Linux PC, and configuring the xAP connector to drive the display. This is a quick-and-dirty route in many respects, tying up a valuable serial port on the PC, and also quite costly - off-the-shelf displays with a serial interface seem to demand a premium. I have imported serial displays from Scott Edwards Electronics (they also have a UK distributor, Milford Instruments), and from CrystalFontz. As a rule of thumb, any display format equal to or smaller than 20x4 will fit into a double gang wall box. A double gang wallbox can be neatly finished using coloured acrylic sheet, which can be cut to size with a sharp knife or hacksaw.
"Naked" 20x4 VFD - phosphorescent green display
20x4 backlit STN LCD. The photo doesn't do the
display quality justice.
The right hand photo shows the VFD installed in a UK double wall box, faced with green perspex cut to fit. The end result looks terrific.
Custom Hardware
The off-the-shelf serial displays can be had for a fraction of the price minus the serial interface. Constructing a DIY, xAP enabled serial interface is one my ongoing projects.
Alternative Displays
Some xAP enabled devices happen to have displays which might also be used to relay status information on demand - such as the SliMP3 player and the TiVo. Both these devices support the same xAP display schema as the standalone displays, so enabling them to display xAP related events as required is trivially easy.
Command Line Options
xap-display [serial port] [instance name] [network interface] [udp port] [debug level]
where:
serial port is the serial port the display is attached to. Under linux this has the form /dev/ttyS0. Under Windows, the serial port may also be specified using conventional DOS notation such as com1. If unspecified, defaults to the first serial port.
instance name is the xAP instance name assigned to this display. Typically this might identify the physical location of the disply (e.g. Kitchen) in situations where multiple displays are in use. The default instance name is LCD.
network interface is the network interface used for outgoing xAP messages. On a Linux and Windows PC host these are named eth0, eth1. Under OSX they are named ne0 etc. By default, eth0 is used. On a Windows PC which has multiple adapters installed, even if they are not active, eth0 may not represent the active interface - some experimentation may be required!
udp port is the UDP port xAP broadcasts on. By default xAP uses its officially allocated port, 3639. Using an alternative port can be useful during isolated testing, however. Be aware that the use of ports below 1024 will fail unless the application is run by a user with administrative privileges. The use of ports below 1024 therefore has security implications and is not recommend.
debug level determines the verbosity of the output written to stdout. Verbose output can be useful for debugging unexpected behaviour. By default, the debug level is 0. Increasing levels of detail may be specified, up to a maximum of 4.
Download
Display Project
Display connector source (requires xAP-lib)
Display connector Windows executable (requires cygwin dll)
Schema
Display schema
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