Multi-IO Expander Beta discussion

[XORadmin]

Just received Multi-IO expander, looking to connect it with Michigan F8R (always) & Disting EX (sometimes). I thought I had this figured out, but the ‘Pullup’ for each I2C on the back of the expander is giving me pause.

Multi-IO & F8R are in the same case… so I want to connect F8R GND/SCL/SDA to Multi-IO I2C-B GND/SCL/SDA, correct? Though I cannot find in any documentation if Pull-up on multi-IO i2c-B should be set to 5 volt or ‘none’.

For Disting EX in different case with XOXO I2C expander, I’d like to connect it to front of Multi-IO (assuming this is I2C-A?). If this is only connected sometimes (changed while power is off of course), should I2C-A pull-up be set to none, 3.3, or 5v?

Also, is this correct?
|  |  |  = none
0 0  |  = 3.3
|  0  0  = 5

Thanks for the help!

The Multi-IO supports 3.3 and 5 Volt I2C busses. If the F8R doesn't have an own pullup (which you could probably check in its manual) then you need to use the pullup with the Multi-IO. In nearly all cases 3.3 Volt pullup should be fine. I only added the 5 Volt in case something would need it. I came across 3.3V only with eurorack modulaes so far. But I also thought about connecting sensors etc which sometimes use 5 Volt.
Anyways, you can start without the pullup and if it doesn't work, then use the 3.3V. Even if the other gear uses its own pullup it would still work well together with the Multi-IO pullup.
Indeed, as the installation manual describes you connect GND to GND, SCL to SCL and SDA to SDA.

Your jumper drawing is correct, I would connect only one pin of the jumper if I would want the 'none' configuration so I got the jumper always available when I need to change the configuration.