TMR1 question

[yasser hassani]

Hello dear reader
I want to measure the time between revolution wheel.I use UGN3113(Hall Sensor Effect)
I try to write code
IS my code works propper?
...
symbol hall_sensor=portb.1

define OSC 12

DEFINE LCD_DREG PORTD

DEFINE LCD_DBIT 4

DEFINE LCD_RSREG PORTD

DEFINE LCD_RSBIT 2

DEFINE LCD_EREG PORTD

'DEFINE LCD_EBIT 2

DEFINE LCD_BITS 4

DEFINE LCD_LINES 2

overflow var byte

time var byte

pause 200

trisb=%00011110

t1con=%0011001

pir1.0=0

pie1=%00000001

on interrupt goto ISR

intcon=%11000000

main:

LCDOUT $FE,1

LCDOUT "Overflow:",#overflow

time=(17*overflow)/100

LCDOUT $FE,$C0

LCDOUT "time:",#time

pause 100

goto main

ISR:

if hall_sensor=0 then

overflow=overflow+1

else

overflow=0

endif

pir1.0=0

resume

enable

end

Can you help and guide me for making it correct and better.I used an LCD for checking my code.But LCD only shows below things:
Overflow:255
time:43

Iam waiting for your helpful reply