Using a duex5 with expansion board`

[timothyz]

Is there anything wrong with using the duex5 with an expansion board in line? I do not plan on using the enable pins on the expansion board, and as fat as I can tell, that is the only possible issue with this scheme.

Any thoughts?

[timothyz]

Probably should clarify, I would be connecting them using a ribbon cable with 3 connectors.

[dc42]

You can use a DueX2 plus expansion board (using just the 3 stepper driver outputs on the expansion board that are distinct from the 2 on the DueX2). You can't use a DueX5 + expansion breakout board because the firmware will assume you are using the TMC2660 drivers on the DueX5.

You can use the 2 sets of stepper driver outputs on the CONN_LCD connector at the same time as a DueX5.

[timothyz]

@dc42 Ahh, okay, I just ordered some Duex2s, just curious, what components would I need to remove from the Duex5 to make the firmware see it as a duex2? Would it be enough to desolder R66, R4, R19, and R20? (I looked at the do not populate notes in the schematic)

Thanks,
Tim

[dc42]

You should only need to remove or move 1 resistor, the one that sets the signal level on the I2C expander chip that the firmware reads to determine the type of expansion board.

Unfortunately you would need to remove the 3 stepper drivers too, or cut some traces. Or cut the 3 wires in the ribbon cable that feed the CS/EN signal to the 3 DueX5 drivers that you won't be using, and tie those three wires to +3.3V on the DueX5. Otherwise those stepper drivers will drive the SPI bus when you enable the 3 external drivers. This is because the same MCU pins drive the CS pins of the onboard drivers and the EN outputs of the expansion breakout board.