Callback function after stepper movement is completed

[rqi14]

Hi. Many thanks for sharing this awesome project! As an amateur to hardware programming, I can't imagine how my projects can be done without your fantastic library.

My project involves controlling a slider to the desired place from a PC client. The Move() and MoveTo() functions are very helpful achieving this. However, currently the PC client does not know whether it is finished, unless querying the steppers in a loop. I am wondering if there is already a way to insert a callback function to the engine so that it will be executed to let the pc know the movement has finished. I know there is already a blocking option in the movement. My program invovles controlling multiple stepper motors so blocking is hard to deal with.

[gin66]

No, there is no such way and it would be a new feature. Definitely easier, than the callback for the enable pin, which is actually a callback at beginning and end of the movement.

[gin66]

The main problem is, that a callback is running in scope of the cyclic stepper task (or for avr in scope of an interrupt service routine, for which interrupts have been enabled - so kind of multitasking light). This means, any callback ideally does not restart the motor or does any time consuming work. Consequently, it is difficult to get this right from application side.

For avr devices, I think polling in the loop makes sense. For esp32 it would be a mechanism of choice, but actually a separate task with medium priority, which is polling and mostly sleeping for milliseconds, can accomplish the same and that task can check for many motors and do the time consuming work, too.

If anyone can offer a PR, I will look at it. But I doubt, that I will work on this.