AN1794 datasheet(9/34 Pages) STMICROELECTRONICS

9 / 34 page

AN1794

Stepper motor drive

9/34

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 will be turned off (bridge completely disabled) whenever the disable button

is clicked.

13. 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/sec2) = 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.

14. 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.

3.2

Indexing mode

The system can be switched to operate in the positioning (indexing) mode by clicking on

"switch to INDEXING MODE". In the indexing mode a new box appears on the right of the

screen. You can enter up to twelve indexed movements in the box and the wait time between

each movement. When started, the software will execute each movement by accelerating up

to the peak speed, moving the required number of steps and then decelerating back to a

stop so that the total distance moved is the number of steps indicated, then wait the

indicated time before starting the next movement. A negative number entered in the relative

position will cause the motor to run in the "reverse" direction.

AN1794 Datasheet(PDF) 9 Page - STMicroelectronics