Stepper motor driver
UM0696
8/15
Doc ID 15599 Rev 2
●
Running speed: set running speed to about 100 steps/sec
●
Deceleration rate: set deceleration rate to about 1000 steps/sec
2
●
Acceleration current: set acceleration current to about 25%. This is an initial guess as
to the required setting and may need further adjustment. Generally higher acceleration
rate settings require higher acceleration current settings so that the stepper motor does
not start to "slip poles" and fall behind the desired position. Since we have initially set
the acceleration rate setting quite low, 25% is probably adequate.
●
Running current: set the running current to 25%. In practice the running current can
often be set to a lower value than the acceleration current since the torque requirement
is generally less during the constant speed part of the move. A lower running current
setting can help to keep the device and the motor running cooler.
●
Deceleration current: set the deceleration current to 25%. Since friction aids in
decelerating the motor it may also be possible to set the deceleration current lower.
●
Holding current: set the holding current to 25%. Whenever the motor is stopped (after a
run,) this level of current circulates in the motor so that it holds position against any
mechanical disturbance. In the case of a strong static load (perhaps a gravity load of
some sort) it may be necessary to increase this setting. If not much holding torque is
required, then the setting can be reduced so that operating temperatures can be held to
a minimum.
Note:
Holding current is turned off (bridge completely disabled) whenever the disable button is
clicked.
●
Run: make sure that the motor is free to turn in either direction and click the run button.
The motor should quickly come up to speed ((100 steps/sec)/(1000 steps/sec
2
) = 0.1
sec.). To change the motor direction, click the direction toggle switch. If the motor does
not run click the stop button, increase all four current settings to 50%, and click run
button. If the motor still does not run an oscilloscope and current probe should be used
to observe the motor current.
●
Stop: click stop to stop the motor
After the basic operation of the system has been verified, the acceleration rates, top speed,
and current settings can be adjusted to see how the motor responds.