Addition of Stepper Motors as devices

[M-square]

I usually control stepper motors. These seem to be missing in Wokwi. I can see a few challenges to implement them

1: Visual apperance - Similar to the Servo, with a shaft where the angular position is visible, like an arrow glued on.
2: Angular position - accuracy/resolution. Steppers can have lots of steps, a small readout of the actual step it is on would be nice. Can be in the visual model or mouseover display.
2a: partial steps - steppers can be halfstepped so such a readout should be with decimal. (Implementation of detecting halfstep might be tricky)
3: Stepper types - bipolar (4 wire), unipolar(5 or 6 wire), are most common(?) but there are several. That means at least two fundamental different devices, in how they react to electrical connections. The visual representation might be different, possibly weakly indicating 2 bipolar coils or 4 unipolar coils.
4: Stepper resolution - An attribute is number of steps/revolution.
5: Gearing, and other mechanical - must be ignored, or you need to write a physics simulator, too. A geared stepper would simply have more steps to complete a revolution.
5a Possibly exception, but as a new device - Stepper with a linear actuator. (like potentiometer and slide potentiometer)
6: Electrical - in the simplified Wokwi simulation the Arduino drives coils directly - no backemf diodes, no transistor/FET, no 12V, no overcurrent etc. Nor do they have limits on steps/second and other RealLife trivia.
7: Driverchips - usually (bipolar) steppers are driven with a chip. In essence they have a Direction and Step input. A suggestion is a Stepper-with-driver device, where the chip is "integrated" (visually as a black pimple on side :-) ) Input lines are the Step, Direction (and possibly Enable ...)
7a: Where chips offer half/quarter steps, one simply uses double/quadruple the step/revolution of the stepper as a simulation.

Simplification: Steppers need only step on transition when coils get correct +/- (fullstep) compared to previous state.

Oh ... and then there are the libraries for Steppers, with/without chips.

[M-square]

Of course I am willing and able to help with a few of the implementation steps.

[urish]

Great summary, thanks! I added this issue to the list of features open for voting, let's see if it gets any votes

[M-square]

Something like this.

[urish]

Perhaps it'll also be useful to include some text indicating the exact angle?

[M-square]

See point 2. Is angle or step units the more relevant? (Depends on what the code is trying to express, what you want to debug) Is an angle in radians, degrees or grad? All are possible options, and maybe they can be controlled by an attribute, as well as on/off of the text. I have also speculated on showing "speed", but thought that is a RealLife problem that the (relative simple) simulation need not reflect.

NB: Should the arrow+shaft be a group so they can be animated as a unit?
NB2: is there a need for some "hidden" small squares that can act as the connecting point for the wire?

[DavidThijs]

Steppers would be awesome but it also requires support for the drivers (eg. TMCxxxx,A4988,DRV8825, or H-bridges like the L298)

[M-square]

The point has been adressed in (6) and (7) in the original post

The Woki is not an electrical simulator, so it really doesn't matter which driver board. Neither do we need a 12V supply etc. There are two types: The ones with a DIR and STEP input, and those with 4 inputs to control two H bridges. The ULN2003 typically used for small unipolar steppers can be skipped in the simulation (sort of like the resistor for a LED). The Microstepping supplied by some driver chips can be effectivly simulated by setting the stepsize of the stepper - at the end of the day, the code in the arduino just sends step pulses and it notches the stepper onwards by n-degrees.
Thus, a stepper with (f.ex) a DRV8825 allready connected would be ok - it just exposes pins DIR and STEP (and enable). And likewise for one with L298 (4 in-pins, two enable).

My reason for the original requst post is to provide a simple visual indication of how much the stepper has been turned by the program, where Serial output is too messy.

[urish]

Update: we have the Wokwi Element for the stepper motor:

https://elements.wokwi.com/?path=/story/stepper-motor--default&args=angle:45;units:degrees;value:45

[urish]

This part has been getting many votes recently, so I'll be starting to work on the actual implementation soon

[urish]

Initial implementation: https://wokwi.com/projects/327324886912467538

I'm keeping this issue open until we also have the docs ready.

The implementation also supports half-stepping (though the Arduino Stepper library doesn't).

This works without a driver, just Arduino driving the coils directly. Would love to get feedback + if you would like to see any driver. please reply with the model name.

p.s. a very good video for understanding how stepper motors work: https://www.youtube.com/watch?v=eyqwLiowZiU

[francisduvivier]

Awesome that we are getting stepper support! Here a vote for the A4988 and/or TB6600 driver. Grts, Francis

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On Mon, 28 Mar 2022, 00:35 Uri Shaked, ***@***.***> wrote: Initial implementation: https://wokwi.com/projects/327324886912467538 I'm keeping this issue open until we also have the docs ready. The implementation also supports half-stepping (though the Arduino Stepper library doesn't). This works without a driver, just Arduino driving the coils directly. Would love to get feedback + if you would like to see any driver. please reply with the model name. p.s. a very good video for understanding how stepper motors work: https://www.youtube.com/watch?v=eyqwLiowZiU — Reply to this email directly, view it on GitHub <#191 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AASZQZ2NVBFBUHR4Q5XAHA3VCDPDPANCNFSM5EVZWU3Q> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>