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
3
1 long blink, followed by 1 short blink - microSD media found, no MP3 files located.
Constant short blinks - Hardware problem with MP3 Decoder.
3 short blinks - microSD media found, at least 1 MP3 file located.
As soon as the MP3 Trigger powers up with 3 short blinks, the on-board navigation switch can be used to play all of
the tracks on the card, regardless of the filenames.
Left - Plays the previous MP3 file in the directory
Right - Plays the next MP3 file in the directory
Center - Starts/Stops the current MP3 file
Using the Trigger Inputs
The MP3 Trigger v2 provides 18 input pins (TRIG01 – TRIG18) that can be used to trigger specific MP3 tracks on the
microSD card. MP3 tracks are associated with triggers by placing a 3-digit number (using leading 0s) at the beginning
of the filename; 001 for TRIG01, 002 for TRIG02 and so on. The rest of the filename can be anything. For example,
the following are both valid names for TRIG14:
“014TRACK.MP3”
“014 Breaking Glass.mp3”
The trigger inputs are active low and pulled high internally. Therefore, they can be activated either by digital outputs
from another microcontroller (such as an Arduino) or by a simple contact closure (switch) to ground. The inputs
support voltage levels of either 5V or 3.3V.
The trigger inputs are made available on the even-numbered pins of a dual row connector, and all the opposing (odd-
numbered) pins are ground, making it easy to wire individual switches or contact closures directly to the MP3 Trigger
v2 board.
Installing a 36-pin dual-row header allows shunt jumpers to be installed on the trigger inputs to automatically
sequence and loop tracks on power-up as follows.
When a triggered track reaches the end, the MP3 Trigger v2 looks to see if any trigger inputs are active, and will
automatically start another track if so. If only the same trigger is active, then that track will restart (loop). If other
triggers are active, the MP3 Trigger v2 will always start the next higher trigger track, wrapping back to 1 after 18.
This, combined with the fact that the MP3 Trigger v2 will automatically start the lowest numbered active trigger on
power up, means that by installing shunt jumpers on the trigger inputs, the MP3 Trigger v2 can be set to automatically
sequence and loop from 1 to 18 tracks on power up with no externally programming or control required. (Beginning
with firmware version 2.40, installing a shunt jumper on a single sequential trigger will do the same thing.)
Using the initialization file describe later in this document, triggers can be reprogrammed to start sequential or
random tracks. For example, if a trigger is reprogrammed to be a random trigger, and that one trigger is shunted
closed, then the MP3 Trigger v2 will power up and continuously play tracks in a (pseudo) random order.
