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???
02/24/09 14:39
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 		 #162749 - Yes, for a car
Responding to: ???'s previous message
Yes it is for a vehicle. The pulse counts are locked by the GM sensor which outputs 4000 pulse counts per mile.

The frequencies where figured by using the stock guage and mapping out the frequency to speed reading. So a common point would be if you put 132Hz 0-12V on the signal pin, the needle will point to 60MPH. This obviously is a linear function hence:

22Hz = 10 MPH
44Hz = 20 MPH....etc.

Since I have no external PLL, that rules that out.

I wonder if I could use the watchdog timer to act as the reference waveform with the indirect interrupt counter......HMM.

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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