Stellaris® Stepper Motor RDK User’s Manual
November 4, 2009 25
Figure 3-3. Chopper Waveform Generation
A summary of the current control software is shown in Figure 3-4. This technique could be applied
to other loads that benefit from a constant current control.
Figure 3-4. Current Control Software Flow
Control Signal
to Gate Driver
Motor Winding
Current (Amps)
High-side MOSFET ON
Low-side MOSFET ON
Blanking
Time
Blanking
Time
Current Threshold
ADC
Sampling
Start of step Chopping continues to end of step
Read ADC Sample
Sample >
Current
Threshold?
ADC Interrupt
(ISR)
Start new
acquisition
Exit ISR
Start OFF blanking
timer
Turn control pin
OFF
Y
N
Turn control pin
ON
Timer Interrupt
(ISR)
Start ADC
acquisition
Exit ISR
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