Count Per Second

[skimask]

Hi,
If that's the only thing the PIC will do this may work:

GEIGER VAR PORTD.0
CNT VAR WORD
ADD VAR WORD
CONTROL VAR BYTE

Start:
  CNT = 0
  COUNT GEIGER, 5000, CNT     'Count pulses for 5 seconds, store in CNT.
  Gosub SaveData
Goto Start

SaveData:
  'Save data to EEPROM here
RETURN

/Henrik Olsson.

Assuming you don't get over 65,535 pulses...
What happens if you overflow too early? I've never tried, but does COUNT kick out before 5 seconds if it hits 65,535, does it roll over...
And don't forget, COUNT is entirely dependant upon the PICs oscillator speed and will only count low to high transitions (not that either of those should matter much).

[HenrikOlsson]

Hi,

Assuming you don't get over 65,535 pulses...

Yes, but you don't since each pulse is said to be 90uS or longer... About the oscillator speed, yes, COUNT depends on the accuracy of the oscillator but so does any other method I can think of.

/Henrik Olsson.

[oslinux]

Cause i have pulses not shorter than 90uS, i can have a max of 11.111 pulses per second, in 5 seconds i can have a max of 55.555 pulses, there's a way to count for more than 5 seconds, (In other words, there's a way to use a variable longer than a word, like a double word) ?

with a double word i could count up to 4.294.967.296 which is 386.550 seconds!

thank you,

Luca

[ronsimpson]

I had a similar problem where the count might exceed 65000.
I divided up the COUNT into 4 COUNTS.
It can be argued that there is holes between each COUNT. It does work! Don't think about the holes. time=4 seconds
rons
COUNT GEIGER, 1000, CNT1
COUNT GEIGER, 1000, CNT2
COUNT GEIGER, 1000, CNT3
COUNT GEIGER, 1000, CNT4

[skimask]

I had a similar problem where the count might exceed 65000.
I divided up the COUNT into 4 COUNTS.
It can be argued that there is holes between each COUNT. It does work! Don't think about the holes. time=4 seconds
rons
COUNT GEIGER, 1000, CNT1
COUNT GEIGER, 1000, CNT2
COUNT GEIGER, 1000, CNT3
COUNT GEIGER, 1000, CNT4

And those 'holes' between COUNT statements will be on the order of a few microseconds anyways and since the pulses are > 90us, it should catch them.

[oslinux]

ok, so i will use one word variable every 5 seconds, everything into an array, and every 500 seconds i will put the array in an external eeprom, this should work!

Now it's only up to the EEPROM that's not working (In the other topic)

Thank you!

Luca

[skimask]

ok, so i will use one word variable every 5 seconds, everything into an array, and every 500 seconds i will put the array in an external eeprom, this should work!

Now it's only up to the EEPROM that's not working (In the other topic)

Thank you!

Luca

Which PIC are you using anyways?