1. Using a SparkFun™ serial LCD with an Arduino
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Using a SparkFun™ serial LCD with an Arduino
SparkFun Serial Enabled 20x4 LCD (part number: LCD-09568) with Arduino Uno

2. Transmits serial data from digital I/O pin to LCD (plugged into Pin 2)
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LCD wiring
back view
RX = Receives serial data from Arduino
GND = ground wire
5V = power wire
Transmits serial data from digital I/O pin to LCD (plugged into Pin 2)
Ground
5V Power
front view

3. LCD and Arduino together
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LCD and Arduino together

4. Programming living with the lab
Text: “Louisiana Tech University” is displayed, with character locations chosen to center the text on the first two lines of the LCD
Integers: The text “i=“ is printed followed by an integer that varies from 1 to 10
Floating Point Numbers: The text “x=“ is printed followed by a number with four numerals printed to the right of the decimal; the value here ranges from to

5. Cursor Position & Printing to the 20x4 LCD
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Cursor Position & Printing to the 20x4 LCD
Row: 1 Column: 5
mySerial.write(197); // move cursor to row 1, position 5
mySerial.write("University"); // print a text string starting at (1,5) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
212
213
214
215
216
217
218
219
220
221
222
223
224
225
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227
228
229
230
231

6. A Complete Sample Sketch
See the Parallax website ( for more details. Custom characters and other features are available for this LCD.
When developing your sketch, print things to the LCD screen only once if they do not change. For example, the text in this sketch is printed once in setup(), while the variables are printed repeatedly in loop().
A Complete Sample Sketch
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/*****************************************************************************/
/* Example program using a Sparkfun 4x20 LCD to output text and numbers. */
/* The following screen is printed: */
/* */
/* | Louisiana Tech | */
/* | University | */
/* | | */
/* | i=8 x= | where 1<=i<=10 and <=x<= */
/* The program prints out both integers and floating point numbers. The */
/* floating point number is printed to four decimal places */
/* */
/* A partial listing of commands recognized by the LCD is provided below. */
/* See the data sheet for the LCD on the Parallax web site for more details. */
/* mySerial.write(254) - control command must be sent before commands below */
/* mySerial.write(1) - clear display and move cursor to top left */
/* mySerial.write(8) - turn display off */
/* mySerial.write(12) - turn display on / hide cursor */
/* mySerial.write(13) - blinking cursor on */
/* mySerial.write(14) - underline cursor on */
/* mySerial.write(16) - move cursor left one space */
/* mySerial.write(20) - move cursor right one space */
/* mySerial.write(24) - scroll left one space */
/* mySerial.write(28) - scroll right one space */
/* mySerial.write(124) - control command must be sent before commands below */
/* mySerial.write(128) - backlight off */
/* mySerial.write(157) - backlight fully on */
/* row and position commands are shown below for all 80 character positions */
/* ROW 0: 128=(0,0) 129=(0,1) 130=(0,2) 131=(0,3) 132=(0,4) */
/* =(0,5) 134=(0,6) 135=(0,7) 136=(0,8) 137=(0,9) */
/* =(0,10) 139=(0,11) 140=(0,12) 141=(0,13) 142=(0,14) */
/* =(0,15) 144=(0,16) 145=(0,17) 146=(0,18) 147=(0,19) */
/* ROW 1: 192=(2,0) 193=(2,1) 194=(2,2) 195=(2,3) 196=(2,4) */
/* =(2,5) 198=(2,6) 199=(2,7) 200=(2,8) 201=(2,9) */
/* =(2,10) 203=(2,11) 204=(2,12) 205=(2,13) 206=(2,14) */
/* =(2,15) 208=(2,16) 209=(2,17) 210=(2,18) 211=(2,19) */
/* ROW 2: 148=(1,0) 149=(1,1) 150=(1,2) 151=(1,3) 152=(1,4) */
/* =(1,5) 154=(1,6) 155=(1,7) 156=(1,8) 157=(1,9) */
/* =(1,10) 159=(1,11) 160=(1,12) 161=(1,13) 162=(1,14) */
/* =(1,15) 164=(1,16) 165=(1,17) 166=(1,18) 167=(1,19) */
/* ROW 3: 212=(3,0) 213=(3,1) 214=(3,2) 215=(3,3) 216=(3,4) */
/* =(3,5) 218=(3,6) 219=(3,7) 220=(3,8) 221=(3,9) */
/* =(3,10) 223=(3,11) 224=(3,12) 225=(3,13) 226=(3,14) */
/* =(3,15) 228=(3,16) 229=(3,17) 230=(3,18) 231=(3,19) */
/* To print variables to the LCD, you need to use the mySerial.print() */
/* command instead of the mySerial.write() command. For example, the command */
/* mySerial.print(x,4) will send variable "x" to the LCD with four digits */
/* beyond the decimal point */
/* Note that you may need to unplug the ground wire to the LCD and reset */
/* the Arduino after uploading sketch to make it display correctly */
#include <SoftwareSerial.h> // use the software serial library
SoftwareSerial mySerial(3,2); // receive data at pin 3; transmit data at pin 2
void setup() {
mySerial.begin(9600); delay(500); // set data rate to 9600 baud; wait for bootup
mySerial.write(254); mySerial.write(1); // clear screen & move to top left position
mySerial.write(254); mySerial.write(131); // move cursor to row 0, position 3
mySerial.write("Louisiana Tech"); // write a text string starting at (0,3)
mySerial.write(254); mySerial.write(197); // move cursor to row 1, position 5
mySerial.write("University"); // write a text string starting at (1,5)
mySerial.write(254); mySerial.write(212); // move cursor to row 3, position 0
mySerial.write("i= x="); // write text string at (3,0) }
void loop() {
float x=0.0;
for (int i=1;i<=10;i++) {
x=x ; // add to variable x
mySerial.write(254); mySerial.write(216); // move cursor to row 3, position 4
mySerial.print(i); // print i at the current cursor position
mySerial.write(" "); // write blanks to cover previous printing
mySerial.write(254); mySerial.write(224); // move cursor to row 3, position 12
mySerial.print(x,4); // print x to 4 decimal places
delay(1000); // delay 1 second between printing numbers

7. Looking at Sections of the Sketch
See the Parallax website ( for more details. Custom characters and other features are available for this LCD.
When developing your sketch, print things to the LCD screen only once if they do not change. For example, the text in this sketch is printed once in setup(), while the variables are printed repeatedly in loop().
Looking at Sections of the Sketch
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/*****************************************************************************/
/* Example program using a Sparkfun 4x20 LCD to output text and numbers. */
/* The following screen is printed: */
/* */
/* */
/* | Louisiana Tech | */
/* | University | */
/* | | */
/* | i=8 x= | where 1<=i<=10 and <=x<= */
/* The program prints out both integers and floating point numbers. The */
/* floating point number is printed to four decimal places */
/* A partial listing of commands recognized by the LCD is provided below. */
/* See the data sheet for the LCD on the Parallax web site for more details. */
/* mySerial.write(254) - control command must be sent before commands below */
/* mySerial.write(1) - clear display and move cursor to top left */
/* mySerial.write(8) - turn display off */
/* mySerial.write(12) - turn display on / hide cursor */
/* mySerial.write(13) - blinking cursor on */
/* mySerial.write(14) - underline cursor on */
/* mySerial.write(16) - move cursor left one space */
/* mySerial.write(20) - move cursor right one space */
/* mySerial.write(24) - scroll left one space */
/* mySerial.write(28) - scroll right one space */
/* mySerial.write(124) - control command must be sent before commands below */
/* mySerial.write(128) - backlight off */
/* mySerial.write(157) - backlight fully on */
Explains what sketch is expected to do
Control Command that must be written before any LCD programming commands.
Commands for programming the LCD
Control Command that must be written before any LCD backlight programming commands.
Commands for programming the LCD backlight
Sketch Continues on Next Slide
#include <SoftwareSerial.h> // use the software serial library
SoftwareSerial mySerial(3,2); // receive data at pin 3; transmit data at pin 2
void setup() {
mySerial.begin(9600); delay(500); // set data rate to 9600 baud; wait for bootup
mySerial.write(254); mySerial.write(1); // clear screen & move to top left position
mySerial.write(254); mySerial.write(131); // move cursor to row 1, position 2
mySerial.print("Louisiana Tech"); // print a text string starting at (0,3)
mySerial.write(254); mySerial.write(197); // move cursor to row 1, position 5
mySerial.write("University"); // print a text string starting at (1,5)
mySerial.write(254); mySerial.write(212); // move cursor to row 1, position 5
mySerial.write("i= x="); // print text string at (3,2) }
void loop() {
float x=0.0;
for (int i=1;i<=10;i++) {
x=x ; // add to variable x
mySerial.write(254); mySerial.write(216); // move cursor to row 3, position 4
mySerial.print(i); // print i at the current cursor position
mySerial.write(" "); // print blanks to cover previous printing
mySerial.write(254); mySerial.write(224); // move cursor to row 3, position 12
mySerial.print(x,4); // print x to 4 decimal places
delay(1000); // delay 1 second between printing numbers

8. Sketch Continues on Next Slide
See the Parallax website ( for more details. Custom characters and other features are available for this LCD.
When developing your sketch, print things to the LCD screen only once if they do not change. For example, the text in this sketch is printed once in setup(), while the variables are printed repeatedly in loop().
living with the lab
Provides a list of command values for each cursor position on the LCD screen
/* */
/* row and position commands are shown below for all 80 character positions */
/* ROW 0: 128=(0,0) 129=(0,1) 130=(0,2) 131=(0,3) 132=(0,4) */
/* =(0,5) 134=(0,6) 135=(0,7) 136=(0,8) 137=(0,9) */
/* =(0,10) 139=(0,11) 140=(0,12) 141=(0,13) 142=(0,14) */
/* =(0,15) 144=(0,16) 145=(0,17) 146=(0,18) 147=(0,19) */
/* ROW 1: 192=(2,0) 193=(2,1) 194=(2,2) 195=(2,3) 196=(2,4) */
/* =(2,5) 198=(2,6) 199=(2,7) 200=(2,8) 201=(2,9) */
/* =(2,10) 203=(2,11) 204=(2,12) 205=(2,13) 206=(2,14) */
/* =(2,15) 208=(2,16) 209=(2,17) 210=(2,18) 211=(2,19) */
/* ROW 2: 148=(1,0) 149=(1,1) 150=(1,2) 151=(1,3) 152=(1,4) */
/* =(1,5) 154=(1,6) 155=(1,7) 156=(1,8) 157=(1,9) */
/* =(1,10) 159=(1,11) 160=(1,12) 161=(1,13) 162=(1,14) */
/* =(1,15) 164=(1,16) 165=(1,17) 166=(1,18) 167=(1,19) */
/* ROW 3: 212=(3,0) 213=(3,1) 214=(3,2) 215=(3,3) 216=(3,4) */
/* =(3,5) 218=(3,6) 219=(3,7) 220=(3,8) 221=(3,9) */
/* =(3,10) 223=(3,11) 224=(3,12) 225=(3,13) 226=(3,14) */
/* =(3,15) 228=(3,16) 229=(3,17) 230=(3,18) 231=(3,19) */
/* To print variables to the LCD, you need to use the mySerial.print() */
/* command instead of the mySerial.write() command. For example, the command */
/* mySerial.print(x,4) will send variable "x" to the LCD with four digits */
/* beyond the decimal point */
/* Note that you may need to unplug the ground wire to the LCD and reset */
/* the Arduino after uploading sketch to make it display correctly */
/*****************************************************************************/
mySerial.print() is used instead of mySerial.write() when you are trying to display variables on the LCD. For example, to display “Tech” on the LCD you would use mySerial.write(), but if you wanted to display an integer that increases by one each iteration, you would used mySerial.print().
Sketch Continues on Next Slide

9. Library used for LCD & setting pins to recieve/transmit
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Library used for LCD & setting pins to recieve/transmit
#include <SoftwareSerial.h> // use the software serial library
SoftwareSerial mySerial(3,2); // receive data at pin 3; transmit data at pin 2
void setup() {
mySerial.begin(9600); delay(500); // set data rate to 9600 baud; wait for bootup
mySerial.write(254); mySerial.write(1); // clear screen & move to top left position
mySerial.write(254); mySerial.write(131); // move cursor to row 0, position 3
mySerial.write("Louisiana Tech"); // write a text string starting at (0,3)
mySerial.write(254); mySerial.write(197); // move cursor to row 1, position 5
mySerial.write("University"); // write a text string starting at (1,5)
mySerial.write(254); mySerial.write(212); // move cursor to row 3, position 0
mySerial.write("i= x="); // write text string at (3,0) }
void loop() {
float x=0.0;
for (int i=1;i<=10;i++) {
x=x ; // add to variable x
mySerial.write(254); mySerial.write(216); // move cursor to row 3, position 4
mySerial.print(i); // print i at the current cursor position
mySerial.write(" "); // write blanks to cover previous printing
mySerial.write(254); mySerial.write(224); // move cursor to row 3, position 12
mySerial.print(x,4); // print x to 4 decimal places
delay(1000); // delay 1 second between printing numbers
Control Command that must be written before LCD display commands
Set baud rate for LCD (related to speed of data transmissions)
Tells the cursor which position LCD to go to
Text strings use mySerial.write() with text in “ ”.
Command changed from mySerial.write() to mySerial.print() because displaying variable values
NOTE: When developing your sketch, print things to the LCD screen only once if they do not change. For example, the text in this sketch is printed once in setup(), while the variables are printed repeatedly in loop().
See the SparkFun™ website ( for more details. Custom characters and other features are available for this LCD.

10. living with the lab
After downloading your sketch, you may need to press the Arduino reset button to remove “gibberish” that may be printed on the LCD.
reset button