Hello,
I want to generate a time delay from 100usec to 1000usec in PWM pulses generated from DSP. These delay will be fix, say 250 micro-sec, 500 micro-sec, 750 micro-sec. So how can I generate this delay. I need a high resolution of say 0.5 micro-second or 1 micro-second. Are there any readymade chips available or can I do it using R-C circuits, or is there any other mean by which I can do it ?
--- You can do it easily using a cheap microcontroller or, if you don't want to do it that way, by using two down-counter chains and some glue logic. Use the leading edge of your input pulse to load the delay into one counter chain and to enable that chain. Then, later on, use the trailing edge of your input pulse to load the delay into the other chain.
When the first chain times out, freeze that chain and generate a single pulse to set an RS latch. When the second chain times out, freeze that chain and generate a single pulse to reset the latch.
The output of the latch will be the delayed version of your input pulse, and the resolution will half that of your counter chain clock if you use both its leading and trailing edges.
-- John Fields Professional Circuit Designer
Usually a fifo is used, at 750 microseconds with 0.5 microseconds resolution, that'd be 1500 flipflops. It might be simpler to have the DSP to delay the pulse.
Rene
-- Ing.Buero R.Tschaggelar - http://www.ibrtses.com & commercial newsgroups - http://www.talkto.net
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