Adding power to DIN MIDI out

Building Zynthian
,
1

Hi,

On a V4.5 kit, I have DIN MIDI out.

This is what it looks like, taken from the building instructions.

IMG_0186
IMG_01861024×683 104 KB

I would like to use it with CME WIDI Master to have reliable wireless MIDI, while not wasting USB slots and not requiring external power. Also, this requires no real extra desk space as it is above the output jacks.

IMG_0185
IMG_0185450×450 23.9 KB

No external power needed

Enjoy the fully standalone wireless solution powered via MIDI Out (3.3v - 5v)

There are other products from the same vendor that already work, but they either require a USB cable or push at stuff stuck in neighbouring USB ports.

My plan:

  • DIN out has 2 connected wires, needed to send the MIDI.
  • If I read the interwebs correctly, I should be able to connect MIDI pin 2 (the middle one, currently unused) to Ground to add power to the MIDI out.

Does this plan sound right, and if so, any recommendations on where to connect the ground to?

Also curious to know if the V5 has this pin connected.

And this also benefits other use cases, e.g. to power a Quadra Merge.

2

The Powering MIDI devices from MIDI is a neat little trick and deserves some analysis (grok).

MIDI uses a 5mA current loop as it’s connection mechanism, and perhaps they missed a device carrying trick in not using current flow as the off state. but either way there is 3.3v or 5V out on a properly presented MIDI connection. What there isn’t is a earth connection, and this is by design, to prevent introducing MIDI as the perpetual cause of big audio ground loops and the perpetually associated mains hum so beloved of guitarists and their ‘interesting’ pedal boards.

Some specialized low-power MIDI accessories (e.g., certain thru boxes or mergers from brands like MIDI Solutions) use a non-standard “phantom power” approach. They draw constant power from the +5V (or 3.3V in updated specs) voltage always present on pin 4 of the MIDI OUT/THRU port, using pin 2 (shield) as a ground reference. This works even in idle states, bypassing full isolation, but it’s not part of the core MIDI spec and risks ground loops or compatibility issues if the source device doesn’t ground the shield properly. Power draw is typically very low (e.g., under 5mA total per device), and multiple can chain if the source can handle the load without voltage drop.

The point about ground loops is well made. and it’s all a bit MIDI non standard..
So, obviously if you were to get the soldering iron out to add the requirement we would have to send the boys round to stop you and deliver considerably too much soup.

MIDI is a VERY fine standard.

3

Yeah. Here be dragons indeed. I thought it was a strange exotic thing myself until I experienced it in action on a Korg Kaossilator Pro+… also it is working out of the box on the Pisound HAT.

For the sake of science I am still curious to make it work while drinking lots of soup…

4

I have a Yamaha Wifi MIDI thingy which was the first time I saw it.
It’s not been usefully employed.
The give away is the cable that connects the two sockets. Power to drive the LED.