DIY USB host - MIDI DIN converter - USBpal released


This looks useful!



Definitely interested, too.

A USB-Midi-out would be really nice, too. I could finally use the OP1-sequencers with the CV-Pal then without the need for a Laptop, couldn’t I?


Looks fantastic. Nice job. I’d suggest doing this as a version 1 (I’d take a PCB), then working on a v2 with more features, like the MIDI IN. Otherwise, the feature creep could go on so long it never gets out there in the wild!


I’d suggest you it on muff’s too!


looks very useful.
i wish i could help out doing beta tests, but i don’t have the time right now. :frowning:


Derailment Warning!

Talking of USB in Euroland, does anyone think a powered USB 2.0 or 3.0 hub, in a slimline Eurorack module would be a good idea?

I have a couple of modules already that have USB sockets on the front, so it would be pretty useful for me.

I did consider buying a cheap hub, and trying to hack it into a module, but obviously designing one from scratch would be a better option, if I knew where to start doing that.



@toneburst What scenario do you think of? Your modules are USB devices? And you want to hook-up them on their way to the computer? Then a hacked hub would be the easiest…


@Picard I’d like to be able to control multiple CVPal or other USB MIDI modules without taking up more than one USB socket on my computer, and/or program multiple programmable modules without having to unplug/replying them.

Now I think of it, though, I don’t know if it’s possible to reprogram reprogrammable modules (using Arduino, for example) when they’re connected via a USB hub. Have to try that…



@toneburst: If you are using a computer, a USB hub would work just fine. Multiple Arduinos will show up on different ports when plugged into a USB hub, but they will all have the same name if they are all the same type of Arduino board. So you won’t be 100% sure which board you are uploading to.

The box Picard is making has special firmware for “class compliant” usb midi devices. You could not use a usb hub with this box.


@audiohoarder thanks for the info :slight_smile:

I don’t currently have any modules that actually incorporate an Arduino board, though if I ever get around to making up my Ardcore DIY PCB, I will have.

I do have a few modules than can be programmed using Arduino. I assume they show up as different devices, though haven’t tested that.



My box will also handle a hub, but since the firmware only accounts for the first device enumerated, it wouldn’t be of much use unless you want to use very long cables…


Update: the new pcb layout is coming to it’s end…


How are the latest specs? MIDI out, MIDI in and two USB host ports? How will be the routing between them?


2 independent USB host ports accepting class compliant MIDI controllers
1 MIDI DIN out
1 hidden MIDI DIN in (patch points for self-service)
1 Mini USB sockets for 5V DC in

The messages on the 3 MIDI in channels (USB1, USB2, hidden IN) are merged in order of appearance to the MIDI DIN out. The first channel that deliver a clock signal after power cycle will be clock master. Clock messages of the other 2 will be skipped. A Sysex on one channel will block the other two until it’s finished. I’m still thinking about how to recover if the sysex end byte get lost. Maybe a timeout…
Firmware is still in progress.


Would it be possible, that at least one of the USB ports act also as MIDI out?
Then you could connect a keyboard to USB1 and a synth to USB2 without any DIN MIDI cables. And you would need only one (powerful) 5V PSU to power all devices.
But it’s already great as it is now!


New layout looks good. Sign me up for a built one, please!


You can also end SysEx state when you receive any status byte. That way you can recover from a truncated SysEx stream automatically.


> I’m wondering if there is somebody out there who would volunteer as a beta-tester?
> Preferably in Germany or Europe and with a certain number of USB MIDI controllers of different brands

I’m in Poland (Wroclaw) and willing to volunteer for beta testing :slight_smile:
What are requirements?
I have an OS X laptop, no windows for using burner dongle…


@cj55: maybe this idea is better for a separate device. unfortunately, I don’t have a usb-only synth…


@elthorno, shiftr, … there is a reason why a USB+DIN merger isn’t on the market… the merge algorithm is a real mess because of the different timings of the ports. If only I had known!