One of our printers is quite large and we decided to use M542 drivers for 3Nm nema24 Z axis motors.
The printer works on RUMBA (Atmega 2560) electronics by RepRapDiscount and we just connected M542 instead of stepsticks.
They work very well.
Another thing is we tried to use servos with DCS 303 drivers from leadshine. It was a great learning opportunity although we dropped it for a while because of some positioning inaccuracies probably due to signal duration differences.

So rounding things up…DUEX is a very special thing used to build extraordinary machines and force them to tackle impossible tasks.
It could have some potential for some of us to have the STEP and DIR pins broken out which not neccessary is a hard thing to do depending on development stage. Probably it's late to bring it up or it already had been but I found the forum a few days ago just to be staggered with how dunamic it is and put this idea.

External drivers possibility all the way.

AFAIK there are no PanelDue 1.1 boards left in the distribution channels, so all PanelDues shipped from this week should be version 2.

Hi Pumlux

The pin outs on the header are different enough that it would either be a really complicated cable, individual pin-pin cables (no recommended for long term use) or a PCB to provide the pin-pin routing.

Currently planned for production is a Duex5 which will have up to 5 channels of TMC2660s populated and a "dumb" interface board for external drivers, see the discussion here:
https://www.duet3d.com/forum/thread.php?id=3

When I design he "dumb" interface board I might be able to add a header for duex4, depending on space and demand.

@bot:

If you cite octoprint as an example of the success of your ideology, then I'd ask you to look into the thousands of user reports of problems setting it up, without even a webcam. Then look into the problems added on top trying to use the odd types of cameras you are talking about. The best success seems to be had from typical USB cameras.

I cited Octoprint as an example of the demand for cameras.

Thousands? That seems a bit hyperbolic. Anyway I can find lots of folks having trouble setting up the 0.8.5, does that mean its a bad board? Same for iPhone, or really any other electronic device more complicated than a toaster. It just means that folks have questions when doing something they've never done before.

@bot:

Just because you CAN do something doesn't mean you should. Have the creators of the duet not already stated there are potential performance issues just by exposing the pins? Did I misread the beginning of the thread?

There are potential issues exposing the high speed SPI pins. I'm not asking for those. So again, what exactly is being compromised by simply bringing some otherwise unused signals out to a header?

Anyway, I'm sorry for causing such a fuss about this.

I like the I2C I/O expander idea. That takes care of things nicely and is probably a cheap add-on.
We actually just used one of those on a project at work. We ran into some issues with hot plugging between boards and probable ESD damage to the chip. Since these expansion boards won't really be meant for hot plugging, that shouldn't be an issue. We were able to "fry" the chip when we did some +/- 4kV safety testing on some connected LEDs on a membrane user interface. Again, probably not an issue on this type of board. Not sure how sensitive the rest of the stuff on the Duet Wifi board is, but I assume you've already dealt with this to some degree. Just wanted to raise a flag because we were recently "burned" by an I2C I/O expander.