The Microcontroller Idea Book - Jan Axelson's Lakeview Research

Chapter 8
Listing 8-4 (page 1 of 2). Initializes a 2-line LCD module and displays a
message on each line.
10 REM address of 8255, Port A
20 A=0FC00H
30 REM address of 8255, Port C
40 C=A+2
50 REM address of 8255, Control port
60 X=A+3
70 REM Control word for Enable (PC.5)
80 E=0AH
90 REM Control word for RW (PC.6)
100 RW=0CH
110 REM Control word for RS (PC.4)
120 RS=8
130 REM Initialize LCD module
140 REM initial values
150 XBY(X)=80H: REM Ports A,B,&C are outputs
160 XBY(X)=E : REM E=1
170 XBY(X)=RW : REM RW=1
180 XBY(X)=RS : REM RS=1
190 REM function set: 8-bit interface, 3 times
200 REM toggle E after each instruction
210 XBY(A)=30H
220 XBY(X)=E+1:XBY(X)=E
230 XBY(A)=30H
240 XBY(X)=E+1:XBY(X)=E
250 XBY(A)=30H
260 XBY(X)=E+1:XBY(X)=E
270 REM function set to match module
280 XBY(A)=38H
290 XBY(X)=E+1:XBY(X)=E
300 REM display on
310 XBY(A)=0CH
320 XBY(X)=E+1:XBY(X)=E
330 REM clear display
340 XBY(A)=01H
350 XBY(X)=E+1:XBY(X)=E
360 REM entry mode set
370 XBY(A)=06H
380 XBY(X)=E+1:XBY(X)=E
146 The Microcontroller Idea Book