frequency counter with pic16f877a

[john120]

can you plz help me to count the frequency and display it on the lcd (4 bit mode).

Thanks

 

[jayanth.devarayanadurga]

Frequency of what pulse input or AC? If pulse you have to use RB0/INT pin for pulse input. If AC then you have to use a circuit to convert AC freq to pulse. Write interrupt code where a counter gets incremented for every external interrupt on pin RB0. Get total interrupts for 10 ms then calculate how many interrupts you get for 1000 ms (1 sec) and it will give the frequency. If you get 500 interrupts for 10 ms then (500 * 1000 ms)/10 ms gives interrupts for 1 sec which is the frequency.

See these projects http://embedded-lab.com/blog/?p=1953
http://icanbuild.it/wiki/index.php?title=Timer0_Counting_AC_Line_Frequency