hi
first of all iwould suggest you yto use 7805 for giving 5v.in the datasheet of jhd 162a its mentioned that operating voltage is 4.5-5.5v.
next please check that db0 of lcd is connected to p1.0 and go on in serial order(this was my problem when i tried)

i am sending mine tested code.though its displaying only 1 letter, it is satisfying to see it on lcd
i have connected rw pin to ground(since using delays)
just configure your correspondig pins and try it.it will work.


org 00h

mov a,#00h
mov p1,a
mov p2,a
mov p3,a
lcall delay
lcall delay

mov a,#38h
lcall lcd_cmd
lcall delay
lcall delay

mov a,#0eh
lcall lcd_cmd
lcall delay
lcall delay

mov a,#01h
lcall lcd_cmd
lcall delay
lcall delay

mov a,#06h
lcall lcd_cmd
lcall delay
lcall delay

mov a,#'Y'
lcall lcd_txt
lcall delay
lcall delay
loop: sjmp loop




lcd_cmd:
mov p2,a
lcall delay
clr p1.2
lcall delay
clr p1.3
lcall delay
setb p1.4
clr p1.4
lcall delay
ret

lcd_txt:
mov p2,a
lcall delay
setb p1.2 ;rs pin
lcall delay
clr p1.3
setb p1.4 ;enable pin
clr p1.4
lcall delay
ret



delay:
mov r2,#03h
loop2:mov r1,#0ffh
loop1:djnz r1,loop1
djnz r2,loop2


ret



end