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Unread 02-05-2008, 18:05
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Re: The 2009 Control System Q&A Thread

Quote:
Originally Posted by The Lucas View Post
Along the same lines, if you had a circuit that took an input pulse then output a pulse of half the length you could double the resolution (kinda like a one-shot with the output length is half the trigger length). Just send it 2ms-4ms (same frequency) pulses and get 1ms-2ms out to the Victor. The couple ms of jitter induced by changing signals between 2ms & 4ms shouldn't affect the servos or the Victors since they just require a minimum length gap between pulses (8ms for the Victors). This circuit could be installed in the place of the current buffer IC on a future rev of the digital sidecar. Just a thought.
... Sorry, I'm having difficulties envisioning any sort of simple pulse width halving circuit. At least one that doesn't involve something like one 555 timer, some logic, and a slew of passives per PWM channel. Or possibly two constant current sources, one cap, a FET or transistor, a Schmitt Trigger, a NOT and an AND... per PWM channel.

Or I suppose you could use a FIFO and clock the unloads twice as fast as the loads and just make sure you're not outputting a high signal for a ridiculously long time...

But on the whole, it seems like a pretty major design undertaking for the digital sidecar. Especially considering it's been prototyped and probably headed for mass production shortly. Making such a modification at this stage of the game would only put it very behind schedule.
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Last edited by Kevin Sevcik : 02-05-2008 at 21:41. Reason: The Sidecar currently being behind schedule was obviously too harsh and unfounded.
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