Lpc2000

If you can sample over 1 second, this is pretty simple.  Just set the
signal up on an interrupt (rising or falling edge).  Count the
interrupts over 1 second.  There will be a +/- 1 count jitter - which is
significant at low frequencies (you might read 0 or 2 hz for a 1 hz
signal).  At 60mhz speed, you can run 300 instructions between
interrupts at 200Khz - about 60 lines of c code.  

 

You can get fancier - for high frequencies you can estimate after
counting for .1 second - leaving some CPU for other tasks.

 

I have to reduce this to code in the next few weeks.


Dan

 

 

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From: lpc2000@yahoogroups.com [mailto:lpc2000@yahoogroups.com] On Behalf
Of lehighuboy
Sent: Thursday, June 09, 2005 10:18 PM
To: lpc2000@yahoogroups.com
Subject: [lpc2000] Re: Frequency counter

 

I need to read the frequency of a 50% duty cycle waveform from 0 to 
200kHz (+/- 1Hz) using the LPC2129. Any suggestions?

Thanks, Garrett

--- In lpc2000@yahoogroups.com, "lehighuboy" <garrett.j.young@g...> 
wrote:
> Does anyone have sample code that counts pulses for a fixed time 
> duration (frequency counter)?
> 
> Thanks, Garrett





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