Confused by TMC2209 pins for AccelStepper

Other Hardware Motors, Mechanics, Power and CNC
1

Hi All...
I am trying to use a TMC2209 driver with a simple 4 wire STEPPERONLINE 2A NEMA 17 stepper motor on a breadboard with my Elegoo Uno starter kit. I know that it has a variety of advanced functions, but I just want to use AccelStepper for now. I am trying to test it with a breadboard on a bench before I build it into the project, and I stymied by the pins, the Vref setting, and the accelstepper interface command.

The oddity is that there are two pins on the driver board in addition to the normal eight on both sides. The VREF and DIAG pins are in the same row as the EN pin. On a typical breadboard, that means those three pins are shorted to each other. Surely that causes a problem, right? One problem I have is that the VREF pot doesn't change the voltage reading on VREF. Could it be that the fact that those three pins are connected by the breadboard is the problem? Am I supposed to bend or cut off those two pins (they extend through the top, too)? Can I not test this on a typical breadboard?

The other thing I don't understand is the dialog needed to tell AccelStepper what motor interface to use. The airspace.com class reference is over my head, I'm afraid. There's FULL4WIRE in enum MotorInterfaceType, then there's driver, uint8_t... it is so new to me. I don't know how to format the simple interface command.

I'm just trying to get a pair of motors to move with a joystick. I found plenty of examples with the little 28BYJ-48 stepper that came with my starter kit, including that the four motor pins had to be fired out of order.

So, are the three pins in a row a problem? Do I cut them off? Is that why the VREF is not reading expected values and changes?
Using the STEP, DIR and probably the EN pins, how do I identify the TMC2209 to AccelStepper?

Any help will be so appreciated.
Sincerely,
rcarbaugh

Link to manual:

2

Yes it does. You must not connect them together. There should be no pins on the bottom side for Vref and DIAG.
From a software point of view, the TMC behaves like an ordinary step/dir driver ( if you don't want to configure it via software). Motor interface type = 1 for AccelStepper.

3

That module's pin layout is not compatible with a standard breadboard - if it comes with separate headers you could perhaps populate only the two rows of pins with headers and connect separately to the other pads (perhaps with female headers on top so that you can connect hook-up leads to the top?)

4

The stepper current will damage, burn, the breadbord contact fingers.