Hello anbar,

first, turn off frames on your email. it makes everyone crazy.

second, what speed is your clock? without that, you cant calculate
the loops.

third, write a loop that makes a known delay. for a 4 mhz clock, a
250 msec delay is nice. this needs an inner and outer loop,

stall
 movlw .250
 movwf acount
outer movlw .110
 movwf bcount
inner nop
 nop
 nop
 nop
 nop
 nop
 nop
 decfsz bcount,f

 goto inner
 decfsz acount,f
 goto outer
 return

now you need this 4 times a second, and (60*5) times for 5 minutes.
because timer0 only runs 0 to 255, you are stuck for how you will set
the countdown, because you cant set for all the seconds. if a
2-second resolution is ok, then timer0 will work once you have the
internal delay set up.

good luck
alice