Picade Plasma Kit Buttons - Midi Controller

Discussion
#1

Hello all!
A quick question (I hope).

I’d like to make a custom midi controller, with feedback from a DAW like Reaper/SunVox so that the colors of the buttons show what’s happening in the DAW.

I was concerned about having an extensive amount of buttons (I’d like a 4x4 button grid), and not having enough GPIO room for things like potentiometers and other inputs.

Question: with the plasma buttons, it seems like I can string them together and get addressable LEDs - do the inputs on the buttons all come through to the Pi on that single interface as well?

If so, I feel like that would give me plenty of GPIO pins for the other types of input I want (a joystick for an X/Y controller, rotating potentiometers and slide pots), etc.

Thanks for any and all pointers prior to buying!

#2

The LED’s are all wired up up a string, kind of like Neopixels. One signal from the Pi feeds the first one in the string which talks to the second which talks to the third etc.
They are Chain-able APA102 addressable RGB LEDs. They use two GPIO pins, one for Data and one for the clock.
I don’t own any, just so you know. I have played around with the Plasma software to drive other LED’s. It worked with the LED on my Fan Shim, found that out by accident when setting it up to work on my Blinkt.
The Button pressed signals are separate, they are just stock Arcade buttons with the LED’s added.

Have you looked at the Keybow?
Pimoroni: Raspberry Pi, Adafruit, micro:bit, and Arduino in the UK

Or maybe even the Pico RGB Keyboard?
Pico RGB Keypad Base – Pimoroni

#3

Thanks, @alphanumeric! While spelunking for an answer, I found many of your comments :)

The LED’s are all wired up up a string, kind of like Neopixels.

Yes, that is what had me excited - that I could, with one port, control the lighting of all buttons and, what I hoped, to have button inputs come through as well.

So my question still stands:

The Button pressed signals are separate, they are just stock Arcade buttons with the LED’s added

I haven’t seen any guides or pictures on how the button inputs are sent? I am a software engineer by trade, and so I’m probably just not Googling correctly - hardware is obviously not my forte :D

Have you looked at the Keybow?

One of the things that will make or break this custom device for me is the tactile feel. If I were going to go with a keyboard, I’d probably use this:

That said, those buttons are EXTREMELY close together, so I wanted to use arcade buttons (both for tactile/touch feeling as well as larger spacing), but I also want the LED’s to be able to be controlled by the DAW/Stepper/Looper things.

So, I think the only question I really have now is how the Picade Plasma buttons send their input signals? If anyone can help me understand that I think I’d be ready to buy.

Many thanks!

#4

I think you’ll find that on the Picade they just ground the GPIO Pin they are wired too. In the Picade they would all have one (side) terminal wired to ground. Pressing the button connects both terminals together. Grounding that GPIO pin. Release the button and its an open circuit. The Picade software watches for a ground on that pin.
Picade X HAT at Raspberry Pi GPIO Pinout

I have some buttons (same as the arcade ones just way smaller) wired up to some of my headless setups to do a shutdown when pressed. I used RPi.GPIO to do the fancy stuff. I used GPIO 5 (BCM number not pin number) but you can use any one you want. Any DATA GPIO anyway.

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)  
GPIO.setwarnings(False)
GPIO.setup(5, GPIO.IN, pull_up_down = GPIO.PUD_UP)

def Shutdown(channel):  
        os.system("sudo shutdown now -P")
        time.sleep(30)


GPIO.add_event_detect(5, GPIO.FALLING, callback = Shutdown, bouncetime = 2000)
#5

I have the Mini Arcade Buttons wired up to my Pirate Radio. I wanted something bigger and easier to use than the itty bitty ones on the pHat Beat. Plus, where my pHat Beat is mounted in my custom enclosure makes it really hard to get at its buttons. They don’t have much in the way of a tactile feel. They don’t click. they just bottom out when pressed. Just a FYI post.

#6

EDIT: Ok. I see the extra connections now after looking up the install guides.

Thank you for the tips. I am unmuddled I think. :P

I was only looking at the LED connections, did not see the other ones for the actual press.

#7

Yeah, there are two other terminals for the button press switch part. It looks like you would pull the two wires off of your original Picade Arcade button, and replace the whole button with the Plasma one. And reconnect the wires. If you were going to use them in a Picade.
You will be wiring them up for something else.