Hi Edward,

This is my approach.

Start a clock counter with the first pulse.
Start a second counter, which counts 5 pulses.
For each pulse counted do these tasks:
1. -Add the clock counter value to a register (2 bytes).
2. -Refresh the clock counter

After 5 pulses you will have 4 intervals.

When the fifth pulse is done, you have time to compute some operations:
1. -Add the clock counter value to a register
2. -Refresh the clock counters and pulse counter
3. -Divide the clock counter saved by 4 (this will take 6 cycles)
4. -Save the two bytes result on epprom.

Continue the loop until what you want.

How about that?

Regards,
Dennis Crawley

P.s.: 0 to 4 degrees in the morning, over Buenos Aires.



----- Original Message -----
From: "Edward Cooper" <edpgc@DSL.PIPEX.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, July 14, 2003 3:00 PM
Subject: [PIC]: Averaging values


> Hi I'm looking for a little help here.
>
> I've built a device that records pulses, it saves the gap between the
> pulses in milliseconds into a 16 bit register (so 65.5 secs max gap)
> Now the actual gap will never be that big.
>
> I want to recall these values from eeprom at a later date and display
> 30 second averages, ie 00-30secs = 12.1secs, 30-60secs = 9.2secs.
>
> I need to store the data as the interval between gaps as it needs to be
> downloaded to a PC later.  What I really need help/ideas with is how to
> process this data into 30sec of gap averages, I'm finding it really
> confusing.
>
> Below is a little drawing of what I'm trying to do:
>
> ..      [        [        [        [       [...
> .. GAP6 [ GAP7   [ GAP8   [ GAP9   [ GAP10 [...
> ..7 SECS[12 SECS [14 SECS [ 11 SECS[ 9 SECS[...
>
> 0-30secs     ][ 30 - 60 SECONDS AVERAGE ][ 60-90secs
>
> Now the issue is that the gap 7 and 10 need to be taken into account
> for the proportion they are inside the 30 second average (30-60). I'm
> sure there is a simple way to do this, however the only way I have
> found involves the following
>   14211 x 14211/30000
>
> now 14211/30000 gives 0 not the 0.4737 i need
>
> Sorry I should probably just come back to this its too hot here, and
> I'm sure this is going to make little sense.
>
> Ed
>
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