Not quite a success case yet


Hey all, first post, thought I’d show where I’ve gotten to in my own build…

So I’m using cobbled together parts - RPi 3B+, Waveshare 3.5 B V2 screen, PiZeroAudio (I do have an Audio Injector Ultra, but we’ll get to that in a bit…), cheap Encoders and a cheap MCP23017 board from Ebay.

So the PiZeroAudio works fine, no issues there. The screen was a bit of a pain to set up, but I know what needs to be done to get it right next time I need to re-do the image:

From an updated image;
Choose the correct waveshare device in webconf
Remove the second line from the Webconf with configuration for the Waveshare touchscreen
Download the drivers from the Waveshare site but don’t install them
install and run the Calibration tool only from Waveshare, not the one that you can run directly from Zynthian

That process got the touchscreen working ok for me.

My PiZeroAudio soundcard gave me no issues at all. The AudioInjector has been a pain from the start, unfortunately. I did get it working at some point, or at least showing under aplay -l. However, after trying to set some levels in alsamixer, it abruptly stopped working, and I haven’t been able to configure it corectly since - multiple new images, but no joy. I did have an issue with a lifted PCB pad, but I thought I’d fixed it (as I was getting the soundcard detected), but maybe I’ve toasted it while trying to fix it, I don’t honestly know. Bit of an expensive mistake, but I’ll survive!

I’m currently wiring up the MCP2-3017, and waiting for some female 40-pin headers to arrive so that I can build my own ribbon cable.

Last night I took an old firewall box and gutted it/cut/drilled holes and now I’ve got a (slightly out of proportion but solid) case for it:

…yes, I accidentally drilled two holes that weren’t meant to be there. They’re going to be given placeholder switches, maybe LED indicators for something, or just covered up… I was considering adding a tiiny joystick (I have some very small 8 way switches with push button operation from another project lying around) but I don’t think I have enough free pins on the MCP23017 to get that done. We’ll see once I’ve gotten the ribbon cable finished.

I’ve tested audio while the device was just a simple stack:

…and it’s working fine (very impressed with the general quality and range of sounds - absolutely stunning and I’ve only explored one or two options!).

I’m very excited to get this up and running in a more stable and well built manner - I’ll be sure to post into the Success Cases thread once I have a more fully featured box to show off!


Congratulations … your pretty close!! And you are the first person, as far as i know, that is using a generic MCP23017 module from ebay. I supposse something like that:

Very good idea!! :ok_hand:

Yes. My experience with AudioInjector soundcards has been a pain too … although when finally you get it working, the sound is not so bad … and audio input is something nice to have :wink:

Yo could use one of them for a “panic button” … as explained here:

Extra Switches: Sustain Pedal, Panic Button, etc



Hey, thanks for the advice!

I’m going to keep on trying with the AudioInjector, but I’ve lost some hope of ever getting it working - the main reason was for the audio in option, but I can live without that until I get it working properly.

I’m trying to contact FlatMax to see if I can order a replacement card without the pre-amp to try and keep replacement costs down, but he’s hard to get a hold of it seems. no rush, I’m pretty sure it was my fault for borking the PCB anyhow.

The MCP23017 version I have is even smaller than the one you posted - it’s this one:

I’m hoping there won’t be any major issues, I just need the headers to turn up so that I can test the encoders along with the screen and soundcard all connected.

A panic button is a brilliant idea - I think a low profile power button (I don’t like the idea of a power button on the front face, but the switch I’ll use is not particularly easy to accidentally press) for one of the holes, and a momentary push switch for a panic button would be perfect!


Which AudioInjector are you talking about?
The Ultra?
I had to replace mine (my fault) and he sent a new one.
It is too expensive to send parts.


Yeah, the ultra, with the separate pre-amp and in/out boards.

If it’s a case of purchasing a new unit entirely I might give it a miss and just get a normal audio injector from (once they come back in stock again and aren’t being price gouged :frowning:)…


When did you try? Because I am the first one who made it work just a couple weeks ago
There is a new entry in the webconf now.
But there are still alsa issues.
I can’t split capture and playback.
Its’ all DAC and always has the same level.
Furthermore the DAC level doesn’t survive a reboot.
It’s always at 100% and that’s too loud.
I made a script at boot time that sets it to 80%


I’ve been trying all this week and last, with new images. I did notice the Ultra setting in the webconf - this didn’t appear to make a difference.

At one point a few days ago I had it reporting as present with aplay -l, and I went into alsamixer, and I think (first time using alsamixer, I was a bit confused) I turned off the only bar that was showing (DAC iirc) and immediately after reboot the card did not show in aplay -l. After that “incident” I’ve not been able to configure it to appear, but I strongly suspect that I did something to the PCB which may have exacerbated the issue.

Frustrating because I did have it working for a brief time, but I do have the PiZeroAudio as a fallback, and at least I can use that to output sound for the time being.


the 40pin is a little tricky. I took a 90deg one.
You are sure, that the new ultra dbo is in /boot and that is used in the config file?
Enough power? it takes more than others


I’ll have a look tonight (at work right now) - the PSU is 2.6A 5v, I think I have a 3A I could also test with in case that’s the issue.


Ohhh! It’s really tiny … :heart_eyes:


I didn’t get time to check the Audio Injector last night, that’s on the back-burner for now in any case.

I had lots of “fun” as the ribbon cables I purchased were ever so slightly smaller in diameter than the headers I had, so I had to separate out each individual wire and carefully ensure they were placed correctly in the little groove/pin - either the wires inside are too small in diameter to make a good connection, or something else is slightly off - there’s a lot of digital noise and crackling when moving the ribbon cable, and no audio when testing - works fine when put together as a stack though.

I’ll play around some more tonight, and consider buying proper sized ribbon cables if I don’t get any joy from what I’ve currently got.

e: Confirmed the MCP23017 linked in a previous post works with no issue - just connecting the cheap Amazon Encoders directly to the board with no debouncing caps works fine. The rainbow dupont ribbon cable won’t do though, way too flaky.

Trying to get a hold of some quality “old school” PATA cables from work at the moment…


So no one at work had 40-pin cables, just the 80-pin type. I wasn’t expecting it to work but by 'eck it did.

I took the headers off the 80 wire cable, pulled out the ground strip, found just enough ribbon cable to make do (about 15cm), swapped some pins around as some are missing in standard ATA cables, and the screen side only needs 26 pins, and clamped it all. I had to unclamp some connectors to fix wonky wire sittings, but it’s sound and stable now.

Here’s Wyleu’s eagerly anticipated rite of passage.


Excellent! I got to see a Gamalan performance in Bali about a hundred million years ago and have been intoxicated by polyrhythm ever since. . .
Nice range of kit as well! Ain’t we lucky little humans? :smiley:


Hehe, I have some recordings of traditional Japanese drumming (not sure what the proper term for the style is to be honest) from around 20 years ago, while I was at university…

Thanks, I like my bleepy box collection :slight_smile: There’s also a QY300 just out of shot, but the disk drive is knackered, I’m just weighing up whether I want to replace it with a USB drive at some cost, or try and repair the drive (I think it’s only the belt that’s loose and old, so not an expensive job).

The QY300, funnily enough, apparently has an unfinished/unreleased Adam and the Ants song on there, they were the previous owners of the box…

Also I just noticed that cases/kits for the MIDIbox SEQ v4+ kits are available again. Damn you temptation!


Stand and Deliver !!!


So, I just received another four encoders and a spare MCP23017 through the post from china that I’d forgotten I’d purchased, which got me thinking…

Could we have 8 encoders working simultaneously?

I assume the MCP23017’s would share SDA/SCL, and two free pins on the GPIO would need to be used for ITA and ITB? Or can ITA/ITB be shared between MCP23017’S?

Then there’s the UI. Could we have 8 encoders visually on screen at once? Possibly replace the centre list of encoder screens with one line at the top right corner, like “1/5” instead of the list?#

Is this the kind of idea where I need to learn how to code it correctly and try to add it myself?


Lot’s of thinking along these sorts of lines… I’d like a second set of Midi sockets for instance.

You have mentioned the major issue in this sort of thing it’s not so difficult to add the hardware but adding it into the code base is more of an issue cos first off how does the poor old Zynth know it’s actually got an extra board on it without a whole extra degree of complexity in the webconf to explain the concept at the very least?

certainly there is an encoder board that jofo put together

So the concept isn’t alien but I think the overall conclusion was do it via USB rather than GPIO simply because it all looked much more flexible that way.