Zynthian using only an LCD screen and midi keyboard

#1

Hi,
I found this project and it looks amazing; although I am not too keen to have such big box with knobs on it, when my synth already has a ton of controls on it (Akai MPK mini MK2).

So I was wondering if there is a way to use Zynthian with just a touch LCD screen, and assign parameters to my midi controller hardware buttons and knobs, so I can avoid to have the knobs harness?

From my understanding the UI is customized to use the knobs so it won’t work out of the box without them. I am not sure how the box UI is built, and if it can be adapted to use touch events instead of rotary encoder signals on GPIO.

Another issue seems to be related to the audio card, I was planning to use a USB cheap audio card, but I am not sure which one is compatible with Zynthian.

Thanks in advance for your help.

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#2

Touch is supported generally. There is one feature which manipulates 2 CCs simultaneously, which isn’t though.
But you can assign knobs of your keyboard as well to replace the original knobs.
But I wouldn’t take an USB sound card but the hifiberry. Of course you can make you frs steps with that usb soundcard and replace it later.

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#3

Most certainly yes. There are many crazed and not so crazed approaches to this, and a wander round the forum will show all kinds of wird and wonderful constructions, mostly with encoders but some without, and I’ve run a zynth entirely in a field using batteries and a Hauwei tablet and a mouse ! Very interesting to compare mouse over to the tablet via VNC and the mouse connected directly to the GUI output :smiley:

Mounting a touchscreen in an environment seems to define the physical problems. I run a lot of 7" Standard’ Touch screens and thou I’d use them in a studio the methods of mounting them in a robust enough fashion for live work is more of issue but it sounds like you don’t see that as a problem so good luck and send us lots of pictures (and sound samples :face_with_monocle:) of how it looks.

The control via external encoders is possible and indeed developing. We have keyboard bindings ( yes both types :slight_smile: ) for the GUI which do allow you to scroll in lists and such like, so you might well find that for remote running you need an enter and back key defined so perhaps they could map to specific keys ( or anything that makes MIDI) but if you end up choosing to provide switches for these function then you really might as well put on 4 encoders which take about as much install design as a couple of switches.

USB audio is not really a viable option but it’s a good way of testing a zynth…
Obviously if you are building a zynth into something else you will need to consider the mounting of the Pi and that needs to be in a corner of an enclosure to allow access to the sockets., and consider the audio connectors.

It’s surprising how quickly you end up as looking at the zynthian case as a pretty good answer. Subject of course to that long standing wyleu gripe, it’s not steel, so I can’t stick it to strong magnets and the annoying Pi people moving a couple of sockets on the board. It’s a good way of mounting a 3.5" screen with a set of encoders.

It also feeds Mofo :smiley:

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#4

I started down that path. I wanted to dip my toes in the water and see if this thing would do what I wanted without jumping in for a full build. I ended up creating so many headaches for myself, and in the end, my build will be almost 90% “Standard Zynthain Kit”. You can save time and money if you just start with a Zynthian kit rather than ending up there.

That said, I got a Hifiberry DAC+ and HDMI monitor working well enough to know that I wanted to make a “road worthy” rig. My build is still a work in progress. I built up an encoder clone, and switched to the 7" touch Pi Foundation screen. Working out the last details on the custom case. I should be ready to post some build photos in August, and hopefully some sound samples soon.

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#5

Aaah how uplifting…
You do realise we keep records :face_with_monocle:

#6

Thanks; so I can use the touch screen without much of a trouble, by installing the zynthian image, or do I have to do something else to get that functionality?
I have a LCD on the pi, so if I put the hifiberry, I can’t plug the LCD on top of it anymore, right?

#7

Agree, the hardest part here is to strike a balance between size of controls on a small 4’’ screen and usability. As far as mounting; I made a plate that would go directly on top of the midi keyboard; so that should ensure that the whole thing is stable.

If there is keyboard support; I may plug a USB micro, like the ones adafruit sell, and use it as keyboard emulator. In that way I can add few buttons if needed, for most common features, without the need to worry about having all on the touch UI. My main limitation is GPIO access, because once I put the LCD on top of the PI, I loose access to every other pin, unless I make a detour with connections; which would make my build very tall at that point.

Pretty sure that people spent time designing the best way to arrange components on the Zynthian; but there may be a chance that they were looking at a specific form factor and find it fitting; which would preclude a different arrangement or layout for the various components. That’s why I am exploring different routes :slight_smile:

#8

Probably what I am looking for is something similar to the original build but slimmer and with less controls. Imagine a standard synth you can buy today, with a large touch screen. Given that you need also other electronics to make it work; I can even consider to split the build between circuitry in the midi keyboard and just leave the monitor and controls out, so I can place them somehow on the keyboard. I wish I had a large 3d printer to make a new case for the midi keyboard… that would be nice to have everything self contained, arranged nicely and in one single block

#9

There is keyboard support now. I have not used it yet.

Here’s a pic of my exploded view before I started to work up a case and front panel. I could have done better with the stack-up, If I had put “through” connectors on the custom encoder board and used right angle dupont for the ribbon connections.
the 7" foundation touch screen uses a flex cable, which attaches to one of the extra connectors right on the pi, so you are not using the gpio header. It helps…

IMG_20190517_181634
IMG_20190517_181634.jpg4032×3024 3.28 MB

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#10

I see, so the screen used by this build does not require to go on top of the GPIO. Mine does; since it goes flush on top of the PI.

I see you have got quite a large stack of boards there; my midi keyboard has space for 3’’ at best, that’s why I went for the flush option on top of the pi for the LCD screen, but the ribbon cable idea is something really interesting, so instead of stacking boards, I can maybe put them side by side.

It will be harder to find place for the plate with the knobs, but I may be able to place knobs around the surface of the midi keyboard; they don’t take much space on the circuit side.

#11

You will want the knobs as close to the “official position” as possible. I find it almost impossible to remember what each function does. If you lump them together, it’ll be trouble.
Between the mock-up and the final faceplate, I moved them to their correct locations in relation to the screen.

#12

You nee something like this
http://shop.zynthian.org/shop/product/zynthian-ribbon-bus-cable-278?category=14

I found mine in the box of old PC spare parts.