DRV8803 Datasheet, PDF (17/26 Pages) Texas Instruments – QUAD LOW-SIDE DRIVER IC

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The Windows Application
Figure 15. SMx
Automatically toggles in correspondence to microstepping radio buttons (see motor control).
3.7 PWM Control
Figure 16. DRV8803 PWM Control
The DRV8803 can be utilized to control DC motors. For the purpose to control DC motor speed, a slider is
provided which applies a PWM to each respective input. The PWM slider consists of an 8 bit number so
positions from 0 to 255 are obtained. The MSP430 directly transforms this 8 bit number into the respective
duty cycle. PWM frequency is around 31.25 KHz.
When the slider bar is moved across, the Duty Cycle indicator is updated accordingly. When the duty
cycle is set from the selector, the slide bar is updated accordingly. The resulting duty cycle is an integer
number between 0 and 100 and it is computed according to the equation:
%Duty Cycle = PWM / 255 x 100
(1)
Each corresponding pin on the chip indicator is toggled automatically. If the duty cycle is 0% the
corresponding chip is toggled to LO (red). If the duty cycle is 100% the corresponding pin is toggled to HI
(green). If the duty cycle is set to anything besides 100% or 0% the corresponding pin is toggled (orange).
SLVU574A – September 2011 – Revised June 2012
17
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