high Accuracy Frequency Counter with AVR Atmega16

[elec1363]

hi
i want to build a high acuracy frequency meter with ATmega16 in the range of
50 HZ to 100 KHZ.
about high accuracy i mean about 0.001 or 0.01 HZ.

I built vary frequency counter already but they haven't high accuracy .
help me how i can do it?

 

[bobsanjose]

Hi,

what are you actually trying to achieve? Measuring a pulse width and calculate the frequency or do you count pulses? If you count pulses, the accuracy is in your calculation because the number of pulses is integer by definition. If you measure the length of a pulse to calculate the corresponding frequency within 0.01Hz in the range of 100 kHz, you need to have a timer that counts 100 steps during one pulse of your signal. In other words, your timer needs to run at 10 MHz min. Don't know if the specific AVR can do that. You would also need a clock from your crystal that is accurate to < 0.1 ppm and your signal you want to measure must no change its frequency within 0.1 ppm.

What kind of application has these needs?
Hope I made no wrong assumptions and it just seems a little out of range for an ATMega16

Bob

 

[elec1363]

dear

in fact i want to buil a frequency meter to measure the freqeuncy.and the accuracy is very important.
for expamle if a function generetor make a 1000.020 HZ my device i want to buil has to show the exact frequency.
and i don't know how to do it?

 

[All4U]

Hi,

what are you actually trying to achieve? Measuring a pulse width and calculate the frequency or do you count pulses? If you count pulses, the accuracy is in your calculation because the number of pulses is integer by definition. If you measure the length of a pulse to calculate the corresponding frequency within 0.01Hz in the range of 100 kHz, you need to have a timer that counts 100 steps during one pulse of your signal. In other words, your timer needs to run at 10 MHz min. Don't know if the specific AVR can do that. You would also need a clock from your crystal that is accurate to < 0.1 ppm and your signal you want to measure must no change its frequency within 0.1 ppm.

What kind of application has these needs?
Hope I made no wrong assumptions and it just seems a little out of range for an ATMega16

Bob

Hi Bob,

I also want to built a accurate frequency meter, however, its required as below:
-uC: Atmel or PIC;
-display: 05 of 7seg led;
-resolution: 0.01 Hz;
-range: 40 - 60 Hz;
-code in: C language;
(actually, i want to built a freg meter to measure freg of 220Vac power supply)
Kindly give me some advice, some example,...

Thanks in front!;-)