This idea was conceived when a friend was discussing how to stream your eurorack output to a Bluetooth speaker. We were thinking which Bluetooth chip/module to use and making a eurorack module for that. But then I was thinking why don't we just put a Pi in your eurorack?
So I started investigating the possibility to use Pi as a Bluetooth transmitter. Turns out, it's pretty simple: use PulseAudio to create a loopback device that loops your USB sound card input (source) to Bluetooth output (sink).
Now the problem is, how can we tell the Pi which Bluetooth speaker to connect to? A good interface in this case is an OLED + rotatory encoder and some menu interface. At this point, I realized there are a lot of things you can do. Such as recording your track, streaming audio/video online, etc. The possibilities are endless!
After a long break and Thanksgiving holiday, I finally stopped procrastinating and finalized the boards! There wasn't a lot of things changed, I added some grounding vias to the header board and adjusted the silk font size, so they look nice and tidy. Overall, for 3 sets of these costs me exactly $39 USD at OSH Park. If these designs proven to work I can open up a store on OSH Park so you guys can build at home too :D
If the demand is there maybe I'll sell kits or complete kits on Tindie. But for the mass production version I'll certainly use DirtyPCB to lessen the cost.
I also need to work more on the software side, maybe this week or the next.
It's time to finalize the hardware to an actual board. I've just finished designing the OLED and encoder board. I decided to use a 8pin JST connector to connect the board to wire.
One part I haven't figured out is how to connect this to the Pi's pins. Given that I just ordered around 300 JST connecters from LCSC, I think I'll design another board that connect's to Pi's header pins which will output 2 connecters, 1) a 2pin 5v power and 2) a 8pin OLED connector.
To mount the board, I have 4 holes on each corner with M2 screw size. As to mounting the Pi to my rack, since I'm using Intellijel's 104HP case, I can use the same rail it uses to mount the power board. The two rails are exactly 7cm apart, and it takes M3 nuts, so I just need to slide it in and screw it on. There will be a "carrier" board to carry the Pi and then that get's screwed to the case. (make sense??)
Another thing I need to design, is the panel that'll go on the rack. Perhaps I'll design 2 types, one for the Intellijel 1U format the other for the other 1U format. This will also hold a 2 port USB extension cable that'll go to the Pi.
A lot has happen since I first created this project. I figured out how to get the OLED to work on the Pi, I figured out how to get the rotatory encoder to work on the Pi, and then I figured out how to write (better) Python.
I don't like breadboards so I went straight to building it on a perf board. Looks good too!
I've created a Github repo for all the code I've written, feel free to check it out. Link is listed on HaD.io project page.
And here are some progress photos:
Coming up next, create more views and submenu and tying tying them to system commands!