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???
02/25/09 20:46
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 		 #162842 - This is no log function, ...
Responding to: ???'s previous message
... but a simple division!

If you have a pulse train of 2.2Hz at a speed of 1MPH and you check with the /INT input how many periods of a 5kHz reference clock fit into one period of the pulse train, then the corresponding formula is:

COUNTS = 5000 / (SPEED x 2.2)

So, at a speed of 1MPH, for instance, you get 5000 / (1 x 2.2) = 2273 counts.


To get the speed from the counts take the reverse formula:

SPEED = 5000 / (COUNTS x 2.2)

Well, your simulator tells something different...


Kai

List of 49 messages in thread
TopicAuthorDate
Tip for Speed sensor via External Interrupt            01/01/70 00:00      
   Fresh thoughts.            01/01/70 00:00      
      Try measuring time instead of count for slow pulse trains            01/01/70 00:00      
         The highest frequency would be            01/01/70 00:00      
            Once more - think time instead of frequency            01/01/70 00:00      
            Rough estimation...            01/01/70 00:00      
         On the teatering edge......            01/01/70 00:00      
            Is that not good enough?            01/01/70 00:00      
               I was having issues with that.....            01/01/70 00:00      
                  Did you read this post?            01/01/70 00:00      
                     I think that's the bullseye, I was forgetting....            01/01/70 00:00      
                     Yes, and your solution is in my code...perfect!            01/01/70 00:00      
                        Happy that it works            01/01/70 00:00      
                           I'm using this model.....at least            01/01/70 00:00      
                           I'm using this model.....at least            01/01/70 00:00      
                           Looks like I was blind to the obvious.            01/01/70 00:00      
                              All depends on the input scale            01/01/70 00:00      
                                 That will be the next step.......            01/01/70 00:00      
                                 Per,            01/01/70 00:00      
                                    Would this work for a Random() Seeding?            01/01/70 00:00      
                                       Thermal noise from a diode            01/01/70 00:00      
                        Bisection.            01/01/70 00:00      
                           I was a bit hasty ...            01/01/70 00:00      
   PLL ?            01/01/70 00:00      
      Stability            01/01/70 00:00      
         Yes, for a car            01/01/70 00:00      
            Are you sure?            01/01/70 00:00      
               your math is correct            01/01/70 00:00      
                  Ok, can you please explain...            01/01/70 00:00      
                     Should be minute not seconds, typo            01/01/70 00:00      
                        Two questions...            01/01/70 00:00      
                           Yes, 3.3V is right and works correctly            01/01/70 00:00      
                              Have you read...            01/01/70 00:00      
                                 In more detail...            01/01/70 00:00      
                                 It would take forever to go through all the combos            01/01/70 00:00      
                                    This is no log function, ...            01/01/70 00:00      
                                       This is my solution, and almost there            01/01/70 00:00      
                              do you read datasheets???            01/01/70 00:00      
                                 Yes/No            01/01/70 00:00      
                                    better perfomance if ...            01/01/70 00:00      
         The PLL approach isn't that hopeless...            01/01/70 00:00      
   period measurement            01/01/70 00:00      
      Here is an image of what I think you mean?            01/01/70 00:00      
         what derivative do you use?            01/01/70 00:00      
            I'm using the NXP LPC936            01/01/70 00:00      
         Your drawing is still in the frequency domain            01/01/70 00:00      
            Yes, you're correct, and I undestand, connecting...            01/01/70 00:00      
            Where I'm at and software recap            01/01/70 00:00      
               more step-by-step            01/01/70 00:00      

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