Trying to Find All 48 GPIOs on RedBoard Artemis ATP

Development Boards Artemis
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Hi everyone!

I’m working on a simple project using my new SparkFun boards (RedBoard Artemis ATP and Tsunami Super WAV Trigger). The plan is to use 23 buttons and 23 LEDs, each on its own pin. Pressing a button should trigger a sound on the Tsunami and light up the matching LED — so I’ll need 46 GPIOs in total.

The Tsunami is connected to the Artemis via Qwiic and handles sound playback perfectly using the SparkFun library — no issues there.

Where I’m stuck is with the GPIOs on the Artemis ATP. I’ve read the hookup guide, schematic, and Apollo3 pad mapping several times, and I’ve also searched the forums — but couldn’t find clear answers to some of my questions. (Apologies if this topic has already been answered somewhere and I missed it!)

I found out that pins 39 and 40 (marked SDA and SCL on the board) are used by the Qwiic connection, so I assume I shouldn’t use them for buttons/LEDs.

That said, I’d love some help figuring out whether I can safely use the following pins:

  • Pins 20 and 21 — They look similar to 24 and 25 on the schematic. But I can’t see where I could find them on the board.
  • Pin 30 — I couldn’t find this pin in the schematic at all. Does it even exist on this board?
  • Pins 46 and 47 — I’m not sure if these are actually available or easily accessible on the board.
  • Pins 48 and 49 — It seems these are labeled RX0/TX0. The guide says to avoid them, but I’m not sure why.

Any help would be really appreciated! I’ve been searching and experimenting for days and just need a few more pins to make this thing work. Thanks a lot in advance!

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I think I understood pins 48 and 49 now.. RX0 and TX0 are connected to the USB interface (via the CH340). So I’m aware that if I use them I shouldn’t upload the code via usb, I’ll check how to do it using the J-tag.

Still trying to figure out the others..

sorry if my questions are a bit basic, I’m pretty new to working with these boards.
Really appreciate if you could help!

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Pin 20, 21, 30, 46 and 47 are NOT broken out. You can check apollo3/2.2.1.variants/SFE_ARTEMIS_ATP/config/pins.cpp.

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4

You don’t need an individual input for each of your buttons. It’s common to set them up in a matrix. Sparkfun has a tutorial that explains how it’s done.

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5

You can also use an I/O expander. That part will even scan the matrix for you.

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Awesome, thanks! That sounds like a perfect solution — I’ll gonna try it out!

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Thanks a lot, @paulvha — that helps!

Looks like it’s actually 43 broken-out pins then.. I kept looking because the board page in sparkfun website says “The RedBoard Artemis ATP has 48 GPIO and this board breaks out all of them in an Arduino Mega format”, so I thought I was missing something.

Really appreciate your help!