Hi, I just got a couple of Ksoloti boards to run from a Bitstream 3x midi controller and I’m wondering whether I need to add resistors to the midi ins / outs I’m thinking of adding (if I don’t go te USB route). Thanks in advance for any pointers!
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Hi, if you just got the boards chances are you have revision v0.7, which will make this easy for you. Since v0.7 robust MIDI in and out circuitry is on-board and you will NOT require (nor should you add) any additional resistors to the pins.
220 here, 220 there
everyone safe everywhere
The pins are labeled MI4 and MI5 / MO4 and MO5 because that’s where they go on the traditional DIN jack, pins 4 and 5. MIDI out will additionally connect pin 3 pin 2 (center pin on the DIN jack) to GND and you have the GND pin right there for convenience.
If you use TRS you may have to look up schematics of DIN MIDI VS TRS MIDI (TRS Type A recommended as it has now been definied in the MIDI standard. UNLESS your controller uses Type B, which I remember the Arturias do!)
Wonderful, thanks for clarifying. This seems so brilliantly simple!
I should double check you mean pin 3 on the DIN? as usually it’s pin 2 (the centre pin) for ground.
Thanks again!
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Ah, you’re right! That odd pinout always gets me. Pin 2 is the center pin and goes to GND (shield) on the MIDI out connector.
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Hey @Ksoloti ,
back on reworking my setup, wanted to add a midi device through TRS Midi. Made a picture, I hooked up a WIDI TRS device, all tested, it sends midinotes, so I think my mistake will be how it is hooked up to the board. I think, I’m just confused, about v0.6 and v0.7 and what changed etc.
So what I did:
WIDI Jack is set to Type A. I Hooked up
MI4 → R IN
MI5 → T IN
MO4 → T OUT
MO5 → R OUT
GND → S OUT
I can switch Midi In , but on Midi Out, this is the only constellation, that gives the WIDI jack power, while Midi in is also plugged in. If i switch T and R on Out, it turns off, as soon as I plug in Midi in.
Sooo, I opened “03_gated_keyboard_sine_oscillator.axp”, where on ksoloti software keyboard plays sounds. I don’t get any signal from my midi-keyboard. Also nothing on the midi monitor (rbrt/midi/in/monitor).
Obviously I’m doing something fundamentally wrong, would love to get some help 
My guess would be, that Sleeve on Midi in needs to go somewhere, but no idea.
Thanks in advance!
What is a WIDI TRS device? = WIDI Jack?
What is the reason you hooked up IN pin 4 to ring, but OUT pin 4 to tip? I believe type A would be 5 to tip, no matter if in or out.
So the WIDI thing is powered via the MIDI connector? How are you powering the Core? How power-hungry is the WIDI Jack?
Thanks for the reply!!
Yes
Yes, powered via midi connector, at least that’s how it worked with any other midi device until now. But I also can power it via USB, which didn’t help.
Yeah, I noticed that too. What I meant is, the Out constellation is the only one, that works for getting power from midi out. The Midi in didn’t work either way, so pin 4 to ring and pin 5 to tip and vice versa.
Maybe you can tell me, how you would hook it up from the ground up. Or am I wiring it basically correct and the problem is somewhere else?
Thanks in advance! Appreciate your time!
Does this mean the MIDI type is configurable?
Type A should always be preferred because it has later been defined as standard by the MIDI association.
Up-to-standard MIDI TRS Type A connections to and from Ksoloti would look like this:
MI4 → R IN ("current source")
MI5 → T IN ("current sink", where the data signal travels)
MO4 → R OUT ("current source")
MO5 → T OUT ("current sink", where the data signal travels)
GND → S OUT
NO GROUND on any MIDI in connector! This is to avoid ground loops. Besides there is that optocoupler in the MIDI in circuit, which doesn’t see incoming GND anyway. MIDI in signals are figurative ‘morse signals’ where (usually) a literal LED is lit up inside the optocoupler and the data is reconstructed from the light pattern. Complete isolation is the whole point.
And if you think about it, every MIDI connection is always OUT to IN, so there is a guaranteed GND on the OUT connector which acts as a shield in the cable without creating a loop.
WIDI Jack manual says something about you may need to power it separately via USB-C if you only use one of the MIDI connections, don’t remember which. But generally, your issues might just be insufficient USB power to the Core?