#Nuanced question about USB/MIDI Controllers + Arduino/Raspberry Pi

13 messages · Page 1 of 1 (latest)

forest summit
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I'm no beginner to software, but when it comes to hardware I am mostly an outsider. I enjoy leveraging Pi 4B for various projects, but I have wanted to take on a larger project more recently. I want to make a USB/MIDI controller of various potentiometers, slide pots, buttons, etc. and connect the controller to a raspberry pi with an LCD screen running software that reads the USB/MIDI arduino controller.

My questions are:

  1. Can a single Raspberry Pi 4B be capable of running Pi OS on a 7"+ LCD, outputting sound via RCA or 3.5mm output, and simultaneously also read digital/analogue ins from knobs, faders, buttons, and switches and convert them to USB MIDI for software on Pi OS to interpret or would I be better off using an Arduino in addition to the Pi as the usb midi controller handling the inputs

  2. How can a Raspberry Pi 4B output sound via stereo RCA and 3.5mm simultaneously? How would I leverage a DAC breakout while still being able to use the 4-pole 3.5mm audio jack already on the pi?

  3. In the case that I have both an arduino & raspberru pi 4b, what type of power supply situation would be needed to both power the Pi + LCD and the Arduino? Can I power it from a single power cable?

Apologies if a lot of these questions are naive, I am simply interested in taking on a larger hardware project, but most of my tacit knowledge really exists in software so I'm looking for help, thanks! :)

lilac lark
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Number 1, I believe so...
You will need to figure out how to work the GP io pins.
I do not know how

2, not sure.
That is likely a Linux os thing I would think
Windows is able to output to diff sources if you know what your doing

  1. Each would need their own power supply.

Both the ras pi and arduino can be powered via the io pins or USB
If you choose usb, the ras pi draws a significant amount and needs a high amp usb power source. For usb I would suggest separate power supplies.

The LCD depends on what LCD you get.
Some are powered off 5 volt terminals and others are powered off a power brick that uses wall power.
It really depends on the LCD

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Another thought....
With the IO on the ras pi, you may not need to use the arduino at all.
Though I am not sure how many of thr IO chips are analog vs digital...
For sliders and the like, most of those are analog

vagrant locust
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1 raspberry pis do not have ADCs so you need at least an adc to read the sliders and knobs, the buttons can easily be done on the pi, but using an arduino for all the inputs is probably easier

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3 one power supply for all is the least likely to lead to weird issues

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You should be able to output to multiple audio devices at the same time, though a dac will have much nicer sound than the built in 3.5mm jack

forest summit
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Thank you these are incredible answers.

  1. I could simply then power the arduino with a usb through the raspi right? Just ensure that the current supplied on the raspberry pi is high enough.. like 2-3A?
  2. for the audio output, the jack will need to output one source of audio 'dj headphones'. the other RCA output (and a separate 3.5mm would be nice paired with it) would be the 'main out'. is DAC my only option here? any recommendations :D
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also if anyone has recommendations for the LCD. I want something 6-11 inch with some sort of high FPS, ideally without a touchscreen.. everything seems to be touchscreen.

vagrant locust
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you don't need a fancy DAC, but you're going to need some form of DAC/ usb soundcard because the pi doesn't have enough analog outputs to generate multiple audio outputs

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yes arduino via usb is fine

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high fps is a waste, the pi will struggle to go over 60Hz anyway

lilac lark
mellow sentinel
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Just to piggyback a bit, but @lilac lark s power concerns are def something to consider. A pi4’s usb output is capped (I believe at 1.5 amps) there could be a shield/hat that fits your needs, there are a ton out there