guys i really need help my project is to make a frequency counter (frequency meter) can cout frequency up to 5Mhz using TMR1 or TMR0 i am lookig since 2 weeks in every where but still cant understand cause every body explain it different way than the other ,,,, i just need to know the maximum frequency i can count using both timers and whatt is the relation between the max frequency i can count and the crystal oscillator ?
also lot of guys told me to use TMR1 but why TMR1 and not TMR0 ??? i know TMR1 is 16 bit and TMR0 is 8 bits
for my project i used TMR1 and i really dont know why
as a test i used PWM from pic16f877a and sent the pWM pulse to T1CkI in another 16f877a
but the accuracy wasnt good !! for example a pwm of 15 k HZ was read 15252 HZ an error of 252 HZ ???
also i couldnt read more than 30Khz i couldnt get the needed range from 1 hz to 5Mhz !! also i need good accuracy is the problem in the code??? here is the counter code guys

sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D7 at RB0_bit;
sbit LCD_D6 at RB1_bit;
sbit LCD_D5 at RB2_bit;
sbit LCD_D4 at RB3_bit;sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D7_Direction at TRISB0_bit;
sbit LCD_D6_Direction at TRISB1_bit;
sbit LCD_D5_Direction at TRISB2_bit;
sbit LCD_D4_Direction at TRISB3_bit;
void main() {
int c=0,i=0,n=0;
char txt[5],txt1[5],*res;;
lcd_init();
lcd_cmd(_LCD_CLEAR);
lcd_cmd(_LCD_CURSOR_OFF);
TRISC=1;
TRISB=0;
TRISD=0;
PORTD= 0;
TMR1L=0;
TMR1H=0;
LCD_OUT(1,1,"WORKING..");
delay_ms(500);
lcd_out(1,1," WORKING.");
delay_ms(500);
lcd_out(1,1," WORKING ");
T1CON= 0B00000011;delay_ms(1000);
T1CON= 0B00000010;
c= TMR1L;
i= TMR1H * 256;
n= c+i;
IntToStr(n,txt);
lcd_cmd(_LCD_CLEAR);
delay_ms(100);
lcd_out(1,1," FREQUENCY IS");
delay_ms(100);lcd_out(2,0,txt);
lcd_out(2,7," Hz ");
}

and the PWm code is simple just to generate a pulse with 15Khz
guys am really a newbie please i need help i really need it please explain to me as a newbie
i only have 5 days to finish this project

 

A) wall of text
B) no punctuation
C) code not commented

 

- oscillator frequency ?, is it crystal oscillator ?
- does the compiler know what the frequency is ?
- Timer1 overflows at 65536 and you should count the number of overflows, if the measuring time is 1000ms and want to measure higher frequencies
- signed integer overflows at 32768
- you should zero Timer1 just before enabling it
- are you sure that the PWM-frequency is exatly 15000Hz