Driving step motors with ULN2003 like drivers???

Haloo!!!

I have made 3 axis based on this hal file :
linuxcnc.org/emc2/index.php/english/foru...on-array-ic?start=10
And it works quite well.

Question :
Now when the motor is not turning LinuxCnc keeps one pin high to hold position.
Can I "turn of" of put a "timeout" on "holding position" when movment stops???

Sure but its a bit of work...

Here's one way using a oneshot component, a xor2 component,
and four and2 components (per axis):

Connect the stepgens step-A and step-B signals to a xor2 component.
The output of the xor2 component will now toggle for every step.

Now wire the output of the xor2 component into a oneshot components
trigger pin. Set the oneshot's retriggerable, rising and falling parameters true.
Set a reasonable timeout via the oneshots's width parameter.

Next wire the oneshot's out pin to in0 of four and2 components
and wire the in1 of the four and2 components to the four stepgen
output pins. Finally wire the out pins of the four and2 components
to the parallel port pins.

Thank you very much!!

Although problem is advanced, I am not.

The hardware solution proposed by PCW is simply way above my capabilities,but thanks any way.

This link from andypugh looks like much simpler solution .

Does anyone knows where I should put this code:


> I STILL don't like it. You need a HAL component that looks at commanded
> position
> (comes from axis.8.motor-pos-cmd, I think) and compares current to last
> position.

Whilst also not liking it, this custom HAL component would do the
trick: (It needs to be compiled with comp --install timeout.comp)

component timeout """Reduces motor command to a predetermied value after a
certain number of seconds of no axis motion""";

pin in float position-command-in "link to motor-pos-cmd";
pin in float current-in "link to the PID output";
pin out float current-out "link to the DAC";
param rw float timeout = 10 "timeout in seconds";
param rw float default-current = 0 "current output after timeout";
variable float old_pos;
variable float t = 0;
function _;
license "GPL";
author "Andy Pugh";

;;

FUNCTION(_){
if (old_pos != position_command_in){
t = timeout;
}
else {
t -= fperiod;
}

if (t < 0){
current_out = default_current;
}
else {
current_out = current_in;
}

old_pos = position_command_in;
}

--
atp