Alcorn Mcbride AM-4, Hardware And Software Reference Manual

Page: 66 / 77

60 GPS Operation
Different Sounds, Same GPS Point
If used, the “Set
Background” command
issued in the first
playlist will remain in
effect for subsequent
playlists. As a result,
background music will
not be interrupted when
changing playlists.
The AM-4 GPS operates in Random mode, whereby you don’t need to travel around
your programmed GPS coordinates in order for it to work. That means that you can
go through the first trigger in the GPS playlist, and then skip to the fifth trigger for
example. There is no need to go in any specific order.
What if you want to have the AM-4 play a different sound the second or third time
passing through the same point? For example, say you want to play an “Arrival
Spiel” when passing through a point the first time, and then play a “Departure Spiel”
when passing the same point in the second time.
Here’s how to do this: Make two different GPS playlists; one for the first pass and a
second for the second time. Each playlist contains an entry with the same “Arrival-
Departure” point, but each has a different sound file associated with it.
The last GPS coordinate in the first playlist is a Play command with the file number
corresponding to the second playlist number. Similarly, the second playlist has a last
GPS coordinate with a file number corresponding to the first playlist number. When
these points are passed the AM-4 switches to the new playlist and abandons the old
one.
You can do this for as many different messages you want for the same point. You
just need to decide where you want to switch to the next playlist. Note also that you
do not need to play a sound at the point where the new playlist takes over. All you
need to do is call up the new playlist, at which time it will take over and start looking
for GPS matches before playing a sound.
Connecting an LED or LCD Sign
The serial protocol of
the sign must match the
GPS receiver and be set
at 4800,N,8,1.
Often times public transportation vehicles have external LED or LCD signs to
display route numbers, advertising, or other information. The AM4 can control these
signs based on GPS locations using information contained in the GPS Playlist.
Simply click the “Has LCD Module” checkbox when GPS Builder starts up and
when the GPS Playlist grid is displayed a new column called “LCD Display”. Type
anything you want to display and it will be sent out the serial port to the sign.
Depencing on your specific configuration, you may need to contact Alcorn McBride
and order a special cable assembly to split out the serial port connections for a sign
hook-up.
With regards to programming, you may need to include some special control
characters in the display strings to achieve compatibility with your particular sign’s
protocol. If you’re having trouble getting your sign to work with the AM4, please do
not hesitate to contact Alcorn McBride and we’ll be happy to provide some
assistance.