Zynthian won't start when USB Midi is on

Hi, I’m having this weird issue where my Zynthian simply won’t boot when my midi usb keyboard is on. I’m using a M-Audio Oxygen 25 midi controller and it has an on-off switch. If I power my zynthian on while the controller is on, it does not start at all. If I turn the controller off, it boots normally, but won’t receive any input from the keyboard. If I turn the controller back on while zynthian is on it manages to send input, but controlls screens (admin, snapshot shortcuts etc) rather than midi signal.

Can someone help me?

I have the same M-Audio keyboard and it IS working for me. Best guess here is check your power supply. Low power is the notorious root cause for issues that others are not experiencing.

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Yeah, I believe that can be the issue. It makes sense if it has enough energy to power the zynthian by itself but not enough to power the keyboard as well.

However, I was able to boot it a few days ago, so yeah, that’s weird.

It is good to know someone else who is using the same keyboard without issues. What are the specifications of the power supply you’re using?

Mine is a mutt. It’s a 6A supply soldered directly to a custom hat. I was unable to drive power through the micro USB due to a power hungry 7" Display.

I had many strange and random issues until I got my power supply solid.

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What are your symptoms? Do you get any indication that it is booting but not starting Zynthian? What is happening with the red and green LEDs on the Raspberry Pi? What happens if you boot without the keyboard connected then plug keyboard in?

What PSU do you have? Which Zynthian firmware image are you using and is it fully updated? (There was an issue with earlier versions where JACK failed to start under similar conditions which prohibits Zynthian software running.

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The leds on the inside are blinking but nothing happens other than that.

If I turn zynthian on and then plug in the keyboard the keys seem to control shortcuts to the screens rather than midi sound.

I built/updated my zynthian box in the last few weeks so I believe it is up to date.

Look at the image attached for my power supply specs.

Hi Dizin,

first lesson that I have learned after years of working with Raspberries : never trust what is written on these chinese power supplies. Most of the time, they are simply unable to provide the current announced on the sticker with a true regulated 5V. When you check the voltage with a scope at full load, in many cases, you can see very short voltage drops, and the RPi does not like that at all.

Now, I read that you see LEDs blinking inside. Do you see the red LED next to the USB power supply blinking ? In that case, there is no doubt : the voltage regulator on the Raspberry reports that something is wrong with the power supply. The red LED must be rock solid in all cases.

(And take care with the Zynthian : there is another red LED located on the HiFiberry. Don’t mix them when you look in the case)


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Yes, that’s what I recommend too whenever it is possible : use the two pins on the 40 pins connector to provide power.
Here is the type power supply I use for my RPi projects (the one on the link is for a big project involving 3 Raspberries… :crazy_face:) https://www.meanwell.fr/ac-dc-single-output-enclosed-power-supply-lrs–50–5
And last but not least : these power supplies are just a little bit more expensive than some power supplies sold in computer stores as “almost official RPi PSU” !!

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I’ve got similar psu from aliexpress - it works great and gives stable 5 volts, checked with oscilograph.

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Hey guys, all fixed!

I got a new power supply and now I can boot my zynthian with the controller connected without any trouble. The lightning symbol also completely disappeared from my screen, which confirms I had a very bad power supply, as it used to appear all the time.

To my disappointment, however, my controller continued to control screen shortcuts and not audio. Fortunately, I was able to fix that issue too. It appears the M-Audio Oxygen series have assignment presets which change how the midi controllers interact with the software. I do not know how I changed the preset to the point where it was not even controlling midi audio anymore, but performing a factory reset managed to put everything back to normal.

Thank you all for the help!


Maybe it had got set to MIDI channel 16?

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