January 2018
This is a continuation of an earlier exploration of Adafruit’s FX Sound Board. Previously, I worked with the 2MB version, but soon found I needed more storage for the intended application.
The 16 MB version is basically identical in functionality – just more storage. The attraction of this board is that it is extremely easy to use, and it can do 44.1 Khz 16 bit audio in WAV or OGG. The ease of use comes from a file name-based trigger system whereby you can set sounds for one-shot, random, temporary play, and loop on any one of 11 pins.
Though this board goes together quickly on a breadboard, the time consuming part is calculating how much space you are going to use with your files. I typically work in 44.1 Khz 24 bit (stereo) WAV which is just too big for this platform. So right away there is a compromise to get down to 16 bit. Then, depending on the file, you may need to reduce from stereo to mono.
Using the Sound Devices Audio Time Calculator, I was able to get some pretty good estimates on just how much I would have to reduce my files before putting the files in the naming format required for the FX board.
The basic calculation to keep in mind is 1 min of stereo 44.1 Khz 16 bit audio (WAV) is going to be roughly 10 MB of data.
This calculator did not offer OGG, but it does MP3 which gets you close.
It helps to have a TXT file or notepad handy to work out the mapping of what files you want to do what, and their associated pin so you match them to the hardware correctly.
In this case I landed came up with 11 files that took up about 14.2 MB. I could only get close to the intended result by using OGG format (converted from WAV). I was able to keep some files stereo, but the “NEXT” files are mono. In a sense this doesn’t matter since the speaker I am using doesn’t have good separation, but for a larger system this would matter more.
One odd thing… for some reason the OGG files took forever to transfer from my Macbook to the FX board over a Sparkfun Cerberus cable, even though WAV files zipped right across. I’ve never experienced this before, and the cable has been performing great otherwise. I’m going to toss this out as some strange behavior of my USB hub, which was also in the chain.
The downside to the Adafruit FX Sound Board is that it can only play one sound at a time.
Ultimately, this board will not work for what I would like to do. The Teensy Audio Board is a much better option. Look for a write-up of that after my next Sparkfun order comes in!
February 10, 2018 Update
With so many projects on breadboards, sooner or later one must make time to either pull them apart or build them into something more permanent. The FX Board in this project uses a non-standard footprint, and I didn’t bother to locate any shields or breakout boards because I knew I could make my own.
This build was something I just thought of and executed without drawing it out. Only thing I might change if I make another one for my 8MB board is to pull the power connector in more so that it is flush with the board.
While the Adafruit Sound FX Board is too limited for most things I want to do, it will make an appearance in a future project where I just need a few small files to play one at a time.
