Connecting MS5637 to Pico

Hi Guys,
I’m trying to connect the PiicoDev Pressure Sensor to the Pico and for my project I need to wire them directly. I’m just having trouble with which pins I should be connecting to.
I’ve tried connecting SDA and SCL to both pins 1 & 2 and 5 & 6 and when I run the provided code I get the following error:

Traceback (most recent call last):
  File "<stdin>", line 8, in <module>
  File "", line 69, in __init__
  File "", line 56, in write8
OSError: [Errno 5] EIO

Having a bit of a dig around and I can’t see if I should be connecting to something else.

Thanks for your help.


Hi Tyrel, welcome to the forums!

Just to check, are you following this guide and have correctly installed all the libraries?

And have you setup Thonny as per this guide?

If you’re not using the Piicodev Expansion Board for Raspberry Pi Pico you’ll need to connect SDA and SCL to GPIO Pins 8 and 9, respectively (Physical Pins 11 and 12) if you want to stick with the defaults (checkout the schematic for the Expansion board).

You’ll also need to make sure you’ve connected the I2C power pin to 3.3v output on the Pi Pico (physical pin 36), and not VBUS (Physical Pin 40) as this is connected to the +5v V_BUS pin from the USB power input, and doing so may damage your Piicodev module, and/or your Pico.

A quick google for that error code shows someone else had a similar problem - they were not specifying the device address correctly. Note that 0x10 is not the same as 10; 0x10 (ie 10 base 16) == 16 base 10. See:

Hope this helps! :slight_smile:


Hi All
You have connected the ground wire haven’t you ???
You have not mentioned that and at this end we have no way of knowing. All the software fiddles in the world will not help if basic connections are not correct.
Cheers Bob


Hi Tyrel,

Welcome to the forum!!

@Liam120347 make something use a similar method to what you look to be using on this forum topic: High pitch screeching coming from a board - #3 by Liam120347

You can refernce the green pinout card you should have received in your order as a quick sanity check - making sure to solder all of the connections that Olver and Bob have mentioned ensuring that there arent any shorts. Yellow being SCL or clock and blue being SDA or Data for the PiicoDev cables.

If you could send through a photo of how you have everything connected that would be great to make sure your hardware is all good!



Thanks for the help everyone! Seems to be working now.
Yep, power and ground were connected as above - I’ll keep in mind to mention that sort of stuff in the future.



Great to hear! :smiley:

I’d love to see some pics of what you make, and just let us know if you get stuck on anything again