Using Sparkfun Qwiic GPIO with Pico

I’m running an LED matrix (64x32) using an Interstate 75 board which is a RPi Pico W connected to an interface to the LED matrix (neater solution than about 16 gpio flyleads!).

I need 6 buttons to be read but I no longer have access to the Pico GPIOs, and even if I did there wouldn’t be enough spare. I bought a Sparkfun Qwiic GPIO board which boasts 8 extra GPIO pins by using I2C via a qwiic connector which is provided on the Interstate 75 board. All my problems solved? Nope! It seems that there are no libraries for the Pico (micropython). So I have no way (to my knowledge) of using this board.

Does anyone know a way to test the GPIO pins on the sparkfun board using I2C? Failing that, does anyone know of another way I can add another 6 GPIO pins?

Many thanks

A few here have used this to do what you want.
IO Expander Breakout (
Out of stock at the moment though, unfortunately.
What you need is a Micro python library for the TCA9534U on your current board. I took a quick look but didn’t see anything?

Thank you. That seems as though it might work. I also looked at running Arduino IDE on the Pico which is possible I think, but didn’t seem to work for me on the Interstate 75 (no ports found).
I’m wondering if it would be better to swap the interstate 75 for a Adafruit Matrix Portal M4.

I have a Matrix Portal, and swapped it for the Interstate 75 W.
For me, it was easier to use Micro Python and Pimoroni’s Pico Graphics. It was what I was already used to. I struggled with Circuit Python and Adafruit’s graphics offering. I went Matrix Portal because it had WIFI. At the time of purchase there was no Interstate 75 “W”
Thats just me though, it all depends on what your used to using software / programing wise. And what your displaying on the Matrix. I’m just displaying weather info in a text format.

Interstate 75 with multiple HUB-75 LED matrix panels - Support - Pimoroni Buccaneers

I am creating a game which needs 6 switches for player input. Otherwise I would prefer the interstate 75. However, having studied the pinouts of the pico, there seemed to be 5 GPIO pins that are unused. So with a bit of soldering, that’s 5 switches. And 2 more pins are used for the two switches on the Interstate board, so I could use those pins making 7 spare pins, which is enough and 1 to spare. So maybe it’s just being able to come up with a way to securely solder the wires to the switches so they won’t be subjected to any force.

What switches do plan on using?
I use these a lot for mounting switches etc.
Adafruit Perma-Proto Breadboard PCB - 3 Pack! – Half size (

Thanks for that. I bought these:

Not to use them as they are intended on I2C ports, but just to make the wiring neater. Each player needs to advance an LED on the matrix and undo this if they make a mistake, so dual buttons is perfect, plus of course they are in a kind of case so don’t need mounting.

Those boards are cool. I already have some veroboard so I might be able to use that for the connections.

Those are nice buttons, might have get some of those myself. Thanks for sharing. Did they come with cables?
On a Pico, when possible I use these to get access to the GPIO pins.
Pico Proto (
They don’t work so well when its a Pico W onboard thats already soldered via the castellated edges though