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MP3 Trigger Hookup Guide V24

January 21, 2016

Incorporate sound into your next project easily with the MP3 Trigger.
  • Just want to point out that the WAV Trigger now supports 2048 tracks, not 999. That’s 16 complete banks of 128 MIDI note numbers.

  • There’s also an Arduino serial control library for the WAV Trigger with an example using the Uno here

  • There’s a whole bunch of things that the WAV Trigger can do that the MP3 Trigger can’t, the main things being polyphony, CD quality, uncompressed audio and MIDI. The only thing the MP3 Trigger can do that the WAV Trigger can’t is play MP3 files, but you can easily convert any MP3 to wav. I don’t know why you wouldn’t use the WAV Trigger.

  • You may be able accomplish this without an Arduino. You can program a trigger input to provide the Random function over a range of tracks. Then using the trigger type selection (edge or latched), you can program the desired behavior of the trigger (press once to start continuous random play vs having to press again to play the next selection.) This is all built into the WAV Trigger.

    Once caveat is that the Random track selection is actually pseudo random - meaning that it’s a random sequence of the tracks, but it will be the same random sequence after each power cycle.

  • Thanks for the feedback. Depending on what you mean by “current track”, there are several ways to get this type of info from the WAV Trigger now: The PLO output pin on the WAV Trigger goes low whenever any track is playing, and is high when no tracks are playing. You can connect this to a digital input pin on your Arduino and use it to tell when audio is playing or not.

    Secondly, the GET_STATUS serial command will cause the WAV Trigger to respond with a STATUS message that contains a list of all the tracks that are currently playing, allowing you to determine when individual tracks are completed. Even though the Arduino library does not yet implement this command, it’s still available to use in your Arduino code. See the Serial Control Protocol section here.

    Hope this helps.

  • The WAV Trigger is a “read only” device, and contains no code capable of writing to or modifying the data on the SD card, so I would be very surprised if it were corrupting anything. I’d suspect other things first. If you would like me to have a look at a “corrupted” file, please email it to me at info(at)robertsonics(dot)com. If it’s larger than 4MB, please email me first and we can coordinate a large file transfer.

  • How would you want this to work? When you say fast forward/ rewind, do you really mean going immediately to a specific time in the track? And what do you mean by queueing? The WAV Trigger already provides a load/pause function, which supports preloading multiple tracks and then resuming them so they start in sample-sync.

    And are you talking about serial commands or trigger functions?

  • The WAV Trigger supports up to 2048 tracks. When the serial port is put into MIDI mode, midi channels and note numbers are mapped to track numbers as follows (with the current firmware): Track = (MIDI Channel * 128) + MIDI Note Number.

    Because SD card memory is not an issue, I advise you to loop your sounds in the WAV file and just make the tracks longer than you’d ever hold a note. The WAV Trigger does not currently support arbitrary loop points or seamless looping - looping is always over the entire track and there can be a small (< 5ms) gap at the loop point.

    Here’s a tutorial with links to some Mellotron sound files. Any instrument sample sets that you can load into a sound editor are potentially good to use with the WAV Trigger. I make my own using soft synths.

  • Not using an existing connector. You could always just solder 3 wires to the pins/pads of the 3.5mm jack.

  • You mean like this?

    The WAV Trigger holds 2048 tracks vs the MP3 Trigger’s 255. There are few things the MP3 Trigger can do that the WAV Trigger can’t do better. Just saying.

    Actually, you could connect an XBee S1 module directly to the WAV Trigger’s RX pin and send serial commands over XBee with no on-board Arduino. Just a thought.

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