how to measure line frequency in pic microcontrollers

[raman00084]

i want to monitor the line frequency of ac servo motor with 230v line

how can i measure the frequency in micro controller any ic available
kindly help

regards
kalyan

 

[shaiko]

Too few details to suggest something...

Is it an AC line?
What resolution are you looking for?
What is the sampling speed?

 

[raman00084]

yes it a ac line
error +/- 2% is ok
sampling speed as fast possible

 

[doraemon]

Hello!

It's still unclear. Do you want to measure the frequency of the 230 V line? Just for your
info, it's a known value, and quite accurately.
Now if you're using a frequency variation for a synchrone motor, this is another story.
You can measure it with any micro controller. Even if your micro controller is a 1MHz device,
it will show 20 000 pulses for each period (at 50 Hz), and therefore its accuracy will be
around 1/20 000. More than enough.
Do this with a timer. Everytime you detect a rising 0 crossing of the sine wave, check your
timer, and you will get an exact value of the period.

Dora.

 

[shaiko]

Choose a PIC with an internal 12 bit ADC.
Then you'll have to design an analog circuit that converts your target AC wave to a measurable DC signal.

You'll have to choose your measuring window.
for example: -250v on the AC side will be 0v on the DC side while +250V will be 3v on the DC side.

 

[raman00084]

can i use frequency to voltage converter ic lm2907?

 

[shaiko]

Try these 2 IC's:
LTC1609
LTC2321-16

 

[srenjis]

A Frequency Counter using PIC16F628

**broken link removed**