Multi-IO Expander Beta discussion

[kriskeyman]

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!

[Terekki]

If I get the new Multi-IO Expander can I keep my 2hp Midi expander connected too, having more Midi I/O?

[StoneJunction]

If I get the new Multi-IO Expander can I keep my 2hp Midi expander connected too, having more Midi I/O?

No it replaces it so you get 1 trs in and 1 out.

[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.

[dborowik]

I wired mine as is (3.3V on both A and B from the back) and could communicate with ER-301 and Disting Ex fine : )

Question about the front i2c connection, I guess one has to be carefully to still power off all devices when connecting to the front panel TRS i2c? I have not tried, but I wonder if I ought to be careful with that too!

Amazing expander Thomas, it was worth the wait, I am only scratching the surface..  

[XORadmin]

I wired mine as is (3.3V on both A and B from the back) and could communicate with ER-301 and Disting Ex fine : )

Question about the front i2c connection, I guess one has to be carefully to still power off all devices when connecting to the front panel TRS i2c? I have not tried, but I wonder if I ought to be careful with that too!

Amazing expander Thomas, it was worth the wait, I am only scratching the surface..  

All I2C are equal. Never hot plug or possible death! And I mean the other gear..the Multi-IO got protection for that but that doesn't mean it is not possible to kill it.

[dborowik]

I wired mine as is (3.3V on both A and B from the back) and could communicate with ER-301 and Disting Ex fine : )

Question about the front i2c connection, I guess one has to be carefully to still power off all devices when connecting to the front panel TRS i2c? I have not tried, but I wonder if I ought to be careful with that too!

Amazing expander Thomas, it was worth the wait, I am only scratching the surface..  

All I2C are equal. Never hot plug or possible death! And I mean the other gear..the Multi-IO got protection for that but that doesn't mean it is not possible to kill it.

That's what I thought; good to hear your expander has some protection : P

[kriskeyman]

Though I cannot find in any documentation if Pull-up on multi-IO i2c-B should be set to 5 volt or ‘none’.

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.

The F8R doesn't have much of a manual, but the page does state:

I2C Header: 3 pin header to connect to other I2C devices in your rack, this is an unbuffered connection so cable lengths should be as short as possible (20cm/6" recommended).  There are 4.7k pull up resistors on this connection.

https://michigansynthworks.com/collectio...c-and-midi

... though there are no actual pullup jumpers on the F8R.

[XORadmin]

Though I cannot find in any documentation if Pull-up on multi-IO i2c-B should be set to 5 volt or ‘none’.

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.

The F8R doesn't have much of a manual, but the page does state:

I2C Header: 3 pin header to connect to other I2C devices in your rack, this is an unbuffered connection so cable lengths should be as short as possible (20cm/6" recommended).  There are 4.7k pull up resistors on this connection.

https://michigansynthworks.com/collectio...c-and-midi

... though there are no actual pullup jumpers on the F8R.

Pullup jumpers = pullup resistors.
The jumpers do make the connection to the resistors. So all fine. Start without the jumpers connected.

[Terekki]

Have ordered the multi IO mainly for the knob (and to support Thomas on his developments)just curious what are other users using the X,Y and Z buttons for?looking forward to adding it to the other expanders :-)