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Which Microcontroller To Use For A Frequency Counter

radiotek

May 31, 2011
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There are so many different type and families of microcontrollers out there it makes it very difficult to decide which one to buy. There are 8 bit, 16 bit and 32 bit controllers and so many different manufacturers making these chips it really makes it confusing which one to use for your project. I will need a microcontroller that will be able to count frequencies to at least 40 Mhz. Any suggestions or help would be appreciated.
Frank
 

BobK

Jan 5, 2010
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I can only speak about PICs. Only the 32-bit PICs would be albe to handle 40MHz directly. To use a smaller PIC you could implement an external prescaler.

Bob
 

radiotek

May 31, 2011
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I found a very good website were they are building counters that will measure frequencies uo to 50 Mhz using a PIC 16F628. Maybe I will end up trying this PIC 16F628 if its still available.
http://www.qsl.net/dl4yhf/freq_counter/freq_counter.html
Appreciate your help




I can only speak about PICs. Only the 32-bit PICs would be albe to handle 40MHz directly. To use a smaller PIC you could implement an external prescaler.

Bob
 

BobK

Jan 5, 2010
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Hmm. I guess I am wrong then. I looked at several datasheets, but not that one. The others did not indicate a max clock period when using the built in prescaler. This one indicates 10ns of high and 10 ns of low, whcih means it will handle a 50% duty cycle sqauare wave up to 50MHz. If it is not 50% duty cycle it will be out of spec at that frequency.

Bob
 

Harald Kapp

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Nov 17, 2011
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Do you nedd to count the 40 MHz directly?
Otherwise you could use an external prescaler as Bob suggested. E.g. divide by 10, and count the resulting 4 MHz signal. Easy for many processors. The resulting accuracy will be the same if you count 10 times longer as you would count a 40 MHz signal - provided the signal has a constant frequency.
 
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