I2C/SPI GPIO expander support?

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Hi there! New to this forum, so I hope I’m doing this right! I’m wondering if I2C or SPI I/O expanders could ever be supported in Klipper (MCP23017, MCP3008, etc.) Thinking of this because I think it’d be neat to design an RP2040-based mainboard with a few I/O expanders on it. That could be a really cheap and easy solution in terms of mainboards.

Has this been discussed before? I searched around and couldn’t find anything. I have decent Python skills and preliminary C skills if a PR for this would be welcome, but I might need someone to point me in the right direction. I also have the hardware on hand to do some tests. Thanks!

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sx1509 is already supported. Looks like it is done entirely in python, no mcu code is needed.

From the documentation: “Due to the delay incurred by I2C communication you should NOT use SX1509 pins as stepper enable, step or dir pins or any other pin that requires fast bit-banging.”

klipper/sx1509.py at master · Klipper3d/klipper (github.com)

Configuration reference - Klipper documentation (klipper3d.org)

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Also see:

and

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A post was split to a new topic: It is possible to add PCF8754 as I2C expander?