Luberth Dijkman wrote:
>
> Hello Roman,
>
> No this is not my first time on the list
> i think around 1997 i whas here ( build bob blicks and don zehnders digital/analog
> propeller pic clock)
>
> you say counting pulses for half a second
> i think i dont like that because there could be a missing pulse
> so the error is around 60 rpm i think

Whoops my mistake, you said a RPM meter to 20,000
rpm? So that is up to 333Hz? Sorry I thought you
wanted 20,000Hz.

> what i understand of the code is that its important how many cycles each possible loop
> has
> i think because the pic only has one timer and the timer is used for the input
> if so i dont like that
>
> will take some time but im not giving up

Your [image] didn't come through.
For speeds up to 20,000 RPM (333Hz) maybe try
this;

* when input goes high;
  * get period reading
  * reset timer0, reset byte2 and byte3

* when timer0 overflows (interrupt);
  * increment byte2
  * if byte2 overflows;
    * increment byte3

So when you get the / edge of the input you get
a timer0 count up to 3 bytes, which should be
accurate even down to quite low frequencies.
This should be very easy to do in asm. :o)
-Roman

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