frequency to voltage conversion.

[John S Gwynne]

--------

   In message <940906120059.18c1 at abacus.gsfc.nasa.gov> , you write:
 
| 
| >MAP and BP sensors apparently do not return voltage as output.  Instead
| >the oscillate at a frequency which corresponds to the absolute pressure.
| >What electronics are involved with frequency to voltage conversion?
| 
| Your best bet for accuracy is a frequency counter - this would also tend to 
| eliminate noise (a digital filter if you will).
| 
| Suppose you find out the MAP sensor outputs between 50-150 HZ depending
| on pressure.  Hook up an 8-bit counter and read it every 10Hz.  You'll expect
| readings between 5-15 counts - this is a little low on accuracy but allows fo

That's why the counter circuit I posted a while back is a period counter *not*
a frequency counter. With it's 16-bit pre-scalar and 32-bit count register
running at 10MHz, this task is becomes trivial. Set the pre-scalar to say 4
or 5 cycles, and you will have fast accurate data.... I've used this circuit
to measure frequency as high as 4MHz to one time event lasting up to seven
minutes. Take a look at it; it's only 3 or 4 chips.

                                       John S Gwynne
                                          Gwynne.1 at osu.edu
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