I need to know how to read frequency - frequency

Question

I got port that is on electronic card (Atmel card with 8051 micro controller) . This port named p3_0. The port get '1' or '0' logic.
1 0 1 0
''''''' ''''''''
' ' ' '
' ''''''' '''''' And so on....
I need to use C for 8051 (that is actually original C) and write a code that will know what the frequency is. finally I need the frequency in array of char cause I need to print it to LCD that only know to print char array[];. I use "itoa" function that convert the int number, the 'count' to char array [];. the frequency can be between 16Hz to 90Hz.
This is what I did :
void main(void)
{
init_lcd()///Print command
;print_lcd(1,"The Project"); //Print command
;print_lcd(2,"is starting:"); //Print command
for(i=0; i<20; i++){delay(1000);delay(1000);delay(1000);}
for(i=0; i<20; i++){delay(1000);delay(1000);delay(1000);}
while(1)
{
count = 0;
while(P3_0 == 1)
{
count ++;
init_lcd() //Print command
;print_lcd(1,"Counting..."); //Print command
for(i=0; i<1; i++){delay(1000);delay(1000);delay(1000);}//delay...
}
init_lcd()///Print command
;print_lcd(1,"Done Counting!"); //Print command
for(i=0; i<1; i++){delay(1000);delay(1000);delay(1000);}
;print_lcd(2,itoa(count)); //Print command
for(i=0; i<20; i++){delay(1000);delay(1000);delay(1000);}
for(i=0; i<20; i++){delay(1000);delay(1000);delay(1000);}
}
}
The idea is I check the port and I count every time its '1'. Finally I will decide of a time that every '1' counted and (doing the calculation of what the frequency is)
THE QUESTION IS: HOW CAN I KNOW EXACTLY HOW MUCH 1 IS ON THE FREQUENCY, HOW CAN I?
Also there is thing with the dalay when counting that "take from the frequency".
How can I solve that?
thanks for all who read enter code herethis!!
I really appreciate any help!,
THANKS ALL!

Answer 1

Their is a logic to measure frequency.
8051 has 2 timers/counters, configure one as timer and another as counter and give your frequency input to the counter pin and then start both counter and timer same time( anyhow their'll be 1 machine cycle delay in activating timers but you can compensate it by calculations), before this load counter with suitable value so that your module can measure low frequency. When counter overflows stop timer and and by knowing no. of counts and time elapsed you can calculate frequency.
Hope this logic works.