UM0696
Stepper motor driver
Doc ID 15599 Rev 2
7/15
3
Stepper motor driver
After the system has established the connection to the control board, it initializes the
settings to the last stored settings and open the PractiSPIN™.spmd GUI. For the stepper
motor, the system can operate in either a constant speed or positioning (indexing) mode.
The constant speed mode can easily be used to see that the system is working.
The stepper motor driving window, from which it is possible to select the motor working
configuration, appears.
3.1
Constant speed mode
Figure 4.
PractiSPIN™.spmd constant speed mode window
●
Speed control screen: a large blue button at the bottom of the screen should read,
"switch to indexing mode". If the button reads, "switch to speed control mode", click the
button once to go to speed control mode.
●
Stepping mode: in the stepping mode box, select either normal or half step. Micro
stepping mode is only available when using the STEVAL-SPMD150STP.
●
Device selection: in the device selection box, select the device being evaluated
●
Direction: in the direction box, click the toggle switch to pick forward or reverse. This is
somewhat arbitrary since the direction sense of the motor is unknown. Once the motor
is running, toggle this switch to reverse the motor direction if desired. To reverse the
meaning of the forward and reverse designations, disable the motor (orange disable
button at bottom of screen) and then swap the motor wires at either CN3 or CN4.
●
Decay mode: set the toggle switch to slow decay
●
Acceleration rate: set the acceleration rate to about 1000 steps per sec
2
(steps/sec
2
).
In the PractiSPIN™.spmd system all motion parameters are given in terms of the basic
units of steps and seconds: position in steps, velocity in steps/sec, and
acceleration/deceleration in steps/sec
2
. In order to relate these settings to rotations,
RPM, and RPM/second it is necessary to know the number of steps (or half steps) per
rotation for the stepper motor being used. A common value is 200 steps or 400 half
steps per rotation.
AM04222v1