I use a DRV8825 to drive a stepper motor (1.8°)which rotate a vertical wheel.
everything work fine, I set the max current specified in the motor datasheet and send a step sequence.
But my wheel has 10 boxes in which I put some small parts and when I rotate the wheel 36°, as soos as I put the parts the rotate alone due to weigh.
I use the following sequence:
Enable Pin =0
loop 20 times
(Step =1
wait 40ms
Step=0
Wait 1sec
)
Enable pin =1
the only solution that I find to maintain the wheel in position is to always active the Enable Pin , but the motor get warn even if I don’t send a step sequence.
Could you please explain what happen in the circuitry when enable is active (but no step sent)?
Could you also confirm that there is no problem to leave enable pin always active?
Among other things, the enable pin turns the current to the motor on and off (off when enable is HIGH). The motor will turn relatively freely when the current is off, so if you want the motor to hold its position, enable must be LOW.
It is normal for a stepper motor to heat up, often to the point that it is too hot to touch. If you have adjusted the winding current so that it stays below the maximum for the motor, it will be safe to leave enable activated.
thanks for your answer.
I 'm sorry but I leave the enable pin active (LOW), and my motor are getting really hot (75°C) after several minutes.
the nominal current of the motor is 1.2A, I set Vref to 0.8V so I have 1.13A because I m in full mode (1,6A x 0.71%=1.13), I hope I m right.
the drv8825 is also hot, but the more strange is that at the beginning the motor runs correctly but now is really hot and it lose some step and don’t have enought torque!!!
Is there any setting to do to block the mortor with out enable pin active?
Can you post a link to the motor specifications? Even 75 C is not too hot for some motors.
However, you can always try running with reduced current. That will reduce heating of both the motor and the driver. Set the current limit to a lower value, that still allows reliable operation, and let us know if that helps.
Another option is to use a geared stepping motor. The gears will help hold position when the motor is off.
