Norns Shield - USB Power Output?

Hi Everyone,

I have a quick question I was hoping someone might be able to help me with. I have a Micromonsta 2 on the way (hopefully) that I would like to use with my Norns Shield. The MM2 is USB-powered, and also receives MIDI over USB, so it would be great if I could just plug the MM2 into the Norns Shield. The MM2 website indicates that the synth needs 500mA of power. Is the Norns Shield capable of outputting this power level over its USB ports, or would I be better off powering the MM2 separately and connecting the Shield via MIDI some other way? I guess I could also use a powered USB hub, but I am trying to minimize the cords being used.

Thanks in advance!

From the MM2 FAQ: “Any USB power adapter will work, as long as it is capable of outputting 250mA, that should be the case with all of them now.”

I suppose that’s less than what a 128 grid, or a Polyend Tracker, draws, so you should be fine. The maximum current draw for all USB devices in RPI3B+ is something like 1.2A and I think the individual ports will provide power up to the standard ~500mA spec, given that you use the official PI power adapter or something equally specced.

So even I don’t have a MM2, I’m pretty much certain that it should work. (I wanted to order one of those as well, but waiting for my paycheck and I’m pretty certain they’ll be sold out again when I receive it…)

(Basically what you want to look at is Raspberry PI 3B / 3B+ power specs, as that’s the one providing USB ports and power - the shield is just the encoders, display and ADC/DAC on top of it.)

1 Like

Excellent - thanks for the quick reply! Strange that the MM2 PDF lists 500 mA as the power requirement - maybe it has been changed. In any event, sounds like even 500 mA should work.

I’m very excited to receive it. Just got the notification today at 5 AM and jumped on it, knowing how quickly they sell out. Hope you get one soon!

Good luck! (I guess the 500mA spec could be interpreted, that it wants an USB port supplying the normal “full” 500mA of power, even though the actual current draw was smaller - eg. some mobile devices only supply a much reduced current via USB and that won’t be enough to power the MM2.)

I suppose (or at least hope) there’ll be more batches to come in case I miss this one :slight_smile: I have a newfound love for my Linnstrument, and thought the MM2 it would be great standalone sound source to go with that one, as it should even fit in the Linnstrument gig bag’s side pocket nicely and they’ll both run on USB power.

Yes - that is exactly right. In the interim, I asked Samuel about this, and here is what he said - " 500mA is safer, but it requires less, 250 to 300mA depending on how it is used. But most USB adapters are 500mA minimum, that’s why we rate 500mA."

1 Like

Should be ok, use an appropriate USB power cable (official supply with attached cable, or 5.25V, 2A with 24AWG or bigger if DIY)

In other words, follow standard advice for raspi and hungry usb devices.

Norms shield components themselves might pull… Say up to 100mA with everything cranked

1 Like

Thank you very much!