Basically what you need is an interrupt every 1 second, you can use Timer0 for the purpose. first put timer0 in 16 bit mode, enable timer0 overflow interrupt. Initially set these up

Mov R1,#16
Mov TH0,#31
Mov TL0,#4
Setb TR0

you will get an interrupt every one second.
Crystal frequency must be 11.0592MHz

;-------------------------------------------------------------
; INTERRUPT HANDLER -- TIMER0
;-------------------------------------------------------------
TIMER0:
Mov TH0,#31 // Reload Timer and Run
Mov TL0,#4
Setb TR0
Djnz R1,T0_RET
// One Second elapsed. Call any function you want.
Mov R1,#16
RETI
T0_RET:
RETI