Interruping blocking-mode functions (e.g., limit switch)

[luriomer]

Hello,

In my application I'd like to incorporate limit switches that would stop the motor immediately when engaged (e.g., when reaching a hardstop).
For non-blocking mode functions (i.e., constantly calling run() or runSpeed() inside a loop) it is pretty straight-forward by either interrupts or polling. No problem there.

I wonder if there is a way to do the same for blocking functions, such as runToPosition(). Even if I interrupt to set a flag or whatever, as soon as the ISR function returns (which will be very shortly, if it's just setting a flag) the motor will continue the movement (and if a hard stop was reached it will just slip and won't move).
So basically what I am looking for is a way to use interrupts to conditionally break out runToPosition.

I would say this is a pretty basic feature that many other might need.

Thanks!

[orlin369]

Hey I had the same problem and I thought it has some blocking mechanism. And yes there is. In file: AccelStepper.cpp at line 418 there is :

// Caution 200ns setup time 
// Delay the minimum allowed pulse width
delayMicroseconds(_minPulseWidth);

This part here is blocking the system to run smoothly. The best solution that I was able to do is the flowing:
Add: YIELD; // Let system housekeeping occur
After the 418 line. This will allow you to run the system smoothly and still it is not thew best solution.

Regards
Orlin