User`s manual

Page 12 Alcorn McBride MP3 Audio Machine User’s Manual • Rev H • April 2, 2004
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Parallel Inputs
Be sure to configure the
slide switch before
connecting any wires.
The MP3 Audio Machine can be controlled using either contact closures or voltage
inputs on the female DB-37 Control Connector. A switch located on the side of the
unit next to the connector selects between the two input types. Voltage inputs are
rated for 24 VDC. Consult factory for other voltage options. The table below
describes the function of each input.
Function Voltage
Input
Pins
Contact
Closure
Pins
Description
Mute 11(+),1(-) 1,20 Ramps the audio to zero volume and
maintains it there as long as Mute is asserted.
When Mute is released, audio returns to full
volume.
Pause 12(+),2(-) 2,21 Pauses the file currently playing. Pause is
maintained as long as it is asserted. Play will
resume once it is released.
Stop 13(+),3(-) 3,22 Stops the file currently playing. If the file is a
Play List, it is aborted.
Loop 14(+),4(-) 4,23 Causes the selected file to loop indefinitely
from beginning to end. If the file is a Play
List, all tracks will be played and then the file
will loop. The state of this input is examined
at the end of each file.
File Select 1 15(+),5(-) 5,24 Binary-encoded input plays files 1-15.
File Select 2 16(+),6(-) 6,25 Binary-encoded input plays files 1-15.
File Select 4 17(+),7(-) 7,26 Binary-encoded input plays files 1-15.
File Select 8 18(+),8(-) 8,27 Binary-encoded input plays files 1-15.
The binary file select inputs are used to play the first 15 files. These inputs may be
contact closures or voltages, depending upon the input select DIP switch described in
the previous section. The inputs are change-sensitive; that is, when a change is
detected, the new file will be played. It is therefore important that the four bits
change at about the same time.
If the same file number is selected repeatedly it will normally interrupt itself and
begin again. When processing a play list, if the Play List is selected repeatedly it
advances from entry to entry within the list – unless the “Uninterruptible” flag has
been set (see the Play List section for more information).