MP3 Trigger v2 User Guide
2012.02.01
© 2012 SparkFun Electronics, Inc. All Rights Reserved. Product features, specifications, system requirements and availability are subject to change without notice. MP3
Trigger (WIG-09356) is a trademark of SparkFun Electronics, Inc. All other trademarks contained herein are the property of their respective owners.
MP3TRIGGER_UG_090917
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Quiet Mode
The MP3 Trigger v2 can be placed into Quiet Mode using the serial control port. In this mode, the trigger inputs will
not start tracks but instead will cause serial messages to be sent upon activation. (See “MP3 Trigger v2 Outgoing
Message Summary” below.) This allows the trigger inputs to be decoupled from specific tracks, so that a PC or
microcontroller can monitor the trigger inputs and then start any track or sequence of tracks via the serial control port.
Quiet Mode is off by default and is not preserved through a power cycle.
Serial Control Protocol
The MP3 Trigger v2 comes with a full duplex 3.3-5V serial TTL interface that allows for control of all the MP3 tracks
(up to 256) on the microSD card as well as volume, and for monitoring input trigger activity. You can use our FTDI
Basic (DEV-09115) or connect to any serial interface that uses the format: 8-bits, 1-start, 1-stop, no parity, flow
control = none. The serial port baud rate defaults to 38.4kbps, but can be changed using the initialization file. All
commands to the MP3 Trigger v2 are 1 or 2 bytes in length.
1-byte commands are upper case ASCII characters.
2-byte commands start with an ASCII character. Those starting with an upper case character use an ASCII value (‘0’
– ‘9’) as the second byte. (These commands can be typed on a keyboard.) 2-byte commands starting with a lower
case character require a binary value (0 – 255) as the second byte.
Bytes sent to the MP3 Trigger v2 are not echoed. If echoing is required, set your terminal program to echo locally.
Command Summary
Command: Navigation – Start/Stop
Number of bytes: 1
Command byte: ‘O’
Data byte: none
Comments: This command performs the same function as pushing the on-board nav switch center position. If the
current track is playing, it stops. If the current track is stopped, it will restart from the beginning
Command: Navigation – Forward
Number of bytes: 1
Command byte: ‘F’
Data byte: none
Comments: This command performs the same function as pushing the on-board nav switch right position. The next
MP3 track in the directory will be started.
Command: Navigation – Reverse
Number of bytes: 1
Command byte: ‘R’
Data byte: none
Comments: This command performs the same function as pushing the on-board nav switch left position. The
previous MP3 track in the directory will be started.
