RS equ P2.3EN equ P2.2; put data in RAMMOV 30H, #'H'MOV 31H,
#'E'MOV 32H, #'L'MOV 33H, #'L'; end of data marker MOV 34H, #'L';
end of data marker MOV 35H, #'O'; end of data markerMOV 36H, #0;
end of data marker; initialise the display; see instruction set for
detailsCLR RS ;RS=0 to select Control Reg.
mov a, #20h ; 28 = function set 4bit 5x7 dotsmov P1,aSETB EN;
|CLR EN; | negative edge on ECALL delay; wait for BF to clearSETB
EN CLR EN; | negative edge
mov a, #80hmov P1,aSETB EN; |CLR EN; | negative edge on E;
function set low nibble sentCALL delay; wait for BF to clear
mov a, #00h ; 06 = Entry modemov P1,aSETB EN; |CLR EN; |
negative edge on E
mov a, #60hmov P1,a
SETB EN; |CLR EN; | negative edge on ECALL delay; wait for BF to
clear
; display on/off control; the display is turned on, the cursor
is turned on and blinking is turned onmov a, #00h ;0f= display on
cursor blinkingmov P1,aSETB EN; |CLR EN; | negative edge on E
mov a, #0f0hmov P1,aSETB EN; |CLR EN; | negative edge on ECALL
delay; wait for BF to clear
; send dataSETB RS;RS=1 to select data regMOV R1, #30H; loop:MOV
A, @R1; move data pointed to by R1 to AJZ finish; if A is 0, then
end of data has beenCALL sendCharacter; send data in A to LCD
moduleINC R1; point to next piece of dataJMP loop; repeat
finish:JMP $
sendCharacter:mov p1,aSETB EN; |CLR EN; | negative edge on ESWAP
Amov p1,aSETB EN; |CLR EN; | negative edge on ECALL delay; wait for
BF to clear
delay:MOV R0, #50DJNZ R0, $RET
