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Rasp-Hat-Moteur-Moteurs-pas-a-pas (voir la source)
Version du 30 août 2017 à 20:47
, 30 août 2017 à 20:47→Les pas
There are four essential types of steps you can use with your Motor HAT. All four kinds will work with any unipolar or bipolar stepper motor
There are four essential types of steps you can use with your Motor HAT. All four kinds will work with any unipolar or bipolar stepper motor
#
# '''Single Steps''' - this is the simplest type of stepping, and uses the least power. It uses a single coil to 'hold' the motor in place, as seen in the animated GIF above
# '''Double Steps''' - this is also fairly simple, except instead of a single coil, it has two coils on at once. For example, instead of just coil #1 on, you would have coil #1 and #2 on at once. This uses more power (approx 2x) but is stronger than single stepping (by maybe 25%)
# '''Interleaved Steps''' - this is a mix of Single and Double stepping, where we use single steps interleaved with double. It has a little more strength than single stepping, and about 50% more power. What's nice about this style is that it makes your motor appear to have 2x as many steps, for a smoother transition between steps
# '''Microstepping''' - this is where we use a mix of single stepping with PWM to slowly transition between steps. It's slower than single stepping but has much higher precision. We recommend 8 microstepping which multiplies the # of steps your stepper motor has by 8.
<syntaxhighlight lang="python">
while (True):
print("Single coil steps")
myStepper.step(100, Adafruit_MotorHAT.FORWARD, Adafruit_MotorHAT.SINGLE)
myStepper.step(100, Adafruit_MotorHAT.BACKWARD, Adafruit_MotorHAT.SINGLE)
print("Double coil steps")
myStepper.step(100, Adafruit_MotorHAT.FORWARD, Adafruit_MotorHAT.DOUBLE)
myStepper.step(100, Adafruit_MotorHAT.BACKWARD, Adafruit_MotorHAT.DOUBLE)
print("Interleaved coil steps")
myStepper.step(100, Adafruit_MotorHAT.FORWARD, Adafruit_MotorHAT.INTERLEAVE)
myStepper.step(100, Adafruit_MotorHAT.BACKWARD, Adafruit_MotorHAT.INTERLEAVE)
print("Microsteps")
myStepper.step(100, Adafruit_MotorHAT.FORWARD, Adafruit_MotorHAT.MICROSTEP)
myStepper.step(100, Adafruit_MotorHAT.BACKWARD, Adafruit_MotorHAT.MICROSTEP)
</syntaxhighlight>
== step() - fonction bloquante ==
As you can see above, you can step mulitple steps at a time with '''step()'''
step(number_de_pas, direction, type)
Where ''nombre_de_pas'' is the number of steps to take, ''direction'' is either FORWARD or BACKWARD and ''type'' is SINGLE, DOUBLE, INTERLEAVE or MICROSTEP
{{ambox|text=Note that INTERLEAVE will move half the distance of SINGLE or DOUBLE because there are twice as many steps. And MICROSTEP will move 1/8 the distance because each microstep counts as a step!}}
This is the easiest way to move your stepper but is '''blocking''' - that means that the Python program is completely busy moving the motor. If you have two motors and you call these two procedures in a row:
<syntaxhighlight lang="python">
stepper1.step(100, Adafruit_MotorHAT.FORWARD, Adafruit_MotorHAT.SINGLE)
stepper2.step(100, Adafruit_MotorHAT.BACKWARD, Adafruit_MotorHAT.SINGLE)
</syntaxhighlight>
Then the first stepper will move 100 steps, stop, and then the second stepper will start moving.
Chances are you'd like to have your motors moving at once!
For that, you'll need to take advantage of Python's ability to multitask with threads which you can see in '''DualStepperTest.py'''
The key part of the DualStepperTest example code is that we define a function that will act as a 'wrapper' for the {{fname|step()}} procedure:
<syntaxhighlight lang="python">
def stepper_worker(stepper, numsteps, direction, style):
#print("Steppin!")
stepper.step(numsteps, direction, style)
#print("Done")
</syntaxhighlight>
We have some commented-out print statements in case you want to do some debugging.
Then, whenever you want to make the first stepper move, you can call:
<syntaxhighlight lang="python">
st1 = threading.Thread(target=stepper_worker, args=(myStepper1, numsteps, direction, stepping_style))
st1.start()
</syntaxhighlight>
Which will spin up a background thread to move Stepper1 and will return immediately. You can then do the same with the second stepper:
<syntaxhighlight lang="python">
st2 = threading.Thread(target=stepper_worker, args=(myStepper2, numsteps, direction, stepping_style))
st2.start()
</syntaxhighlight>
You can tell when the stepper is done moving because the stepper thread you created will 'die' - test it with '''st2.isAlive()''' or '''st2.isAlive()''' - if you get '''True''' that means the stepper is still moving.
== oneStep() - fonction non bloquante ==
{{Rasp-Hat-Moteur-TRAILER}}
{{Rasp-Hat-Moteur-TRAILER}}