Compact FLASH Digital Audio System
8
RS-232 Serial Port Protocol
Sound play-out may also be controlled via commands received via the serial port. The data format is
2400 baud, 8 data bits and 1 stop bit. Sounds may be started, queued and stopped using a simple ASCII
protocol:
<SOH> p <+/-/&/~/!> XX <ETX>
where:
Up to 128 sounds may be queued. Sounds that are queued are played in succession in the order that
they were queued only when no other sound is playing until the queue is exhausted or flushed. Note that this
can occur at the end of the BACKGRND.WAV file before it repeats. A background or other sound that is
playing may be stopped by issuing a “
<SOH>p-00<ETX>” serial command sequence to allow queued
sounds to be heard. The background sound will be resumed when the queue has emptied.
Card Requirements
The Compact FLASH Digital Audio System was designed to use only Compact FLASH Cards (CF
Cards) that support the true IDE ATA mode. Tested cards include San Disk, Kingston, Techworks and
Hitachi. The San Disk was tested, since they manufacture 90% of the retail cards on the market. Some
models of the San Disk cards will not work properly with input expansion modules installed. There seems
to be a problem with the San Disk card driving the extra capacitance of an additional expansion module.
Compact FLASH Cards are available in many local electronics or camera stores or can be ordered directly
from ACS.
Diagnostic LED Indicator Codes (Red & Green
LEDs)
Green LED
• Flashes twice a second while scanning or loading CF Card files
• Steady on when loaded, ready or playing
Red LED Error Flashes
• Once every six seconds - problem w/ATA interface, non-compatible CF card, bad CF card
• Twice every six seconds - error opening file for that input, incorrect filename, file does not exist
• Three times every six seconds - error when reading file, file corrupted, unsupported file type
• Four times every six seconds - no valid “*.WAV” files of a compatible format found on the CF Card
<SOH>
= ASCII Start of Header character 01
16
(Ctrl-A)
p
= ASCII lower case letter ‘p’
<+/->
= ASCII plus character ‘+’ to start a sound, mi-
nus character ‘-‘ to stop a sound
<&/~/!>
= ASCII ampersand character ‘&’ to queue a sound,
tilde character ‘~‘ to flush the queued sounds,
exclamation character ‘!’ to stop the current
playing sound and flush the queued sounds
XX
= ASCII two digit hexadecimal number XX
16
of the
sound (01, 02,...,7E,7F)
<ETX>
= ASCII End of Text character 03
16
(Ctrl-C)
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