The Windows Application
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SLVU701B – March 2012 – Revised July 2019
Copyright © 2012–2019, Texas Instruments Incorporated
DRV8834 Evaluation Module
4.1.2
External Microstepper Control
Figure 22. External Microstepper Control
While in this mode, the microcontroller treats the DRV8834 as a dual H-bridge driver with independent
current regulation, motor enablement and phase control. Different than the dual H-bridge control mode in
which two DC motors can be driving, while in this operation style, the microcontroller will recognize
commands to issue high resolution microstepping commutation into a bipolar stepper motor.
In this mode, the Windows application offers control to change motor rotation and select degrees of
microstepping resolution. The decay is programmed into the microcontroller high resolution microstepping
algorithm to follow sine wave shape generation (slow decay while on quadrants 1 and 3, and mixed decay
while on quadrants 2 and 4). Current is set to 1.5-A sine wave peak. To change the maximum current, the
firmware’s internal look up table must be modified.
The Windows application also offers access to the same series of sophisticated algorithms which allow the
stepper motor actuation in both continuous rotation as well as position control mode. The algorithms offer
accurate acceleration and deceleration profiles which help in the obtaining of better motion quality and
performance.
4.2
The CONFIG Control Signal
In this Windows application, the CONFIG control signal is not made available to the user. The application
will modify the control signal according to which TAB is selected. When the communications are made and
any tab gains focus, a serial command is sent to the microcontroller to set the CONFIG control signal
accordingly. If the COM Port is not open, the serial command pertaining to this configuration is not sent.
4.3
Configuring Switches
Although the proper setting of the CONFIG control signal is made automatically, the EVM switches must
still be properly configured if correct operation is to be observed. Failure to properly set these switches will
result in problems with the current regulation and stepper motor functioning.
