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Unread 23-04-2008, 19:19
EricVanWyk EricVanWyk is offline
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Re: Victor logistics.

The victors do contain a microprocessor that measures the duration of the pulse, and sets the duty cycle and direction of its H-bridge. You don't need to be very clever in the conversion: Take the width and map it onto your duty cycle. Here is some bad pseudo code to get you rolling.

Code:
if(width > positive_dead_band):
   direction = positive
   duty_cycle = ( width - positive_dead_band ) / scalar_constant

else if(width < negative_dead_band):
   direction = negative
   duty_cycle = ( negative_dead_band - width ) / scalar_constant

else:
   don't move
If you are attempting to connect a Victor to a hobby servo output, you may need to purchase one of IFI's amplifiers. These simply beef up the drive strength of the signal.

As a point of anality, H-Bridges are controlled by DCM - Duty Cycle modulation, not PWM - Pulse Width Modulation. The two are electrically identical, but conceptually very different.

PWM is a serial communication protocol (albeit a weird one). In a PWM signal, I can adjust the dwell period between pulses without changing the meaning (to a point). Its "inputs" are pulse width and update rate.

In a DCM control, I can adjust the frequency without changing the output (to a point). Its update are percent high and frequency.

Yes, the distinction is completely anal. However, I believe it important so the students can better understand what an H-Bridge does.