Additional GPIO pins on Portenta Machine Control

Hi.

We have a requirement for a lot of 24V digital I/O pins. The 91 available on the Portenta H7/C33 via the high density connectors is a good number for us. From what I have read I can't see anything to suggest that the Portenta Machine Control module allows any more GPIO than the terminals already fixed on the top of the board, unless I have missed something? Is there any way of accessing extra GPIO pins from the high density connectors or from the castellated pins via the machine control module?

My alternative I think will be to use a C33 and build a PCB to allow use of the maximum number of GPIO pins from the high density connector, something similar to this but for 24V:

If anyone may have carried out a similar project I'd be interested to hear about it.

i haven't run in to this yet with any of my projects (Arduino & raspberry pi)

but i think it will come soon for me too

currently I'm working on programming in python with the Portenta Machine Control
and the machine control board is basically a fancy GPIO Expander

adafruit or other shops have those too
# GPIO Expander

Hi @edh84. I have similar requirements to yourself and I got around it with RS485 I/O modules from Akytec. The MU110-24.16R for instance gives you 24x output pins. As @nicodenhertog101 suggested I2C is another route for more I/O.

Please let me know if you come up with a more elegant solution.