View source for LCD-Blue-I2C


<div id="content_view" class="wiki" style="display: block">
=LCD Displays (Blue and Yellow) with I2C/TWI Interface=
[[Image:YwRobotLCD-4x20-400.jpg|right]]
'''IMPORTANT LCD Software Library Info:'''

ALL these displays will now use the great Library written by [https://bitbucket.org/fmalpartida F Malpartida] . You should download that Library [https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads  HERE (Click)] (Get the latest file such as [https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads/Newliquidcrystal_1.3.5.zip Newliquidcrystal_1.3.5.zip] )

If you try to Verify and you see this: <span style="color: #f20f0f">error: 'LiquidCrystal_I2C' does not name a type</span>  ...this means you do not have the library installed correctly. See: [https://arduinoinfo.mywikis.net/wiki/Arduino-Libraries#NewLib How-To-Install-Libraries]  

NOTE!! Move any other LCD libraries to another folder,or rename or delete them.  
 
NOTE! THERE ARE THREE (or More??) VERSIONS OF THE 2 and 4 LINE DISPLAYS. Check the small "backpack" interface board on the back. These small circuit boards on the back interface a 2-wire I2C "I Squared C" bus (plus Ground and +5V power) to the many pins on the LCD display itself. This allows running the display from only 2 signal pins on Arduino. 

The [https://arduinoinfo.mywikis.net/wiki/YourDuino-RoboRED YourDuino RoboRED] (UNO Compatible) has a 4-pin connector that works well for this type display. 
 
[https://arduinoinfo.mywikis.net/wiki/LCD-Blue-I2C#v1 LCD Version 1 - Marked "YwRobot Arduino LCM1602 IIC V1" ] ALSO version marked "A0 A1 A2" on lower right (and also labelled "MH") 

[https://arduinoinfo.mywikis.net/wiki/LCD-Blue-I2C#v2 LCD Version 2 - Marked "Arduino-IIC-LCD GY-LCD-V1"] 

[https://arduinoinfo.mywikis.net/wiki/LCD-Blue-I2C#v3 LCD Version 3 - Marked "LCM1602 IIC A0 A1 A2"]  
These displays are [http://yourduino.com/sunshop2/index.php?l=product_list&c=41 Available HERE:]  

NOTE! These displays are very clear bright white on dark blue (or Black on Yellow) background: it is difficult to get a good digital photo due to polarization effects.  
 
===NOTE! I2C ADDRESSES:===
[https://arduinoinfo.mywikis.net/wiki/LCD-Blue-I2C#scan I2C Address Scanner Sketch HERE]  
The "backpack" modules used on these displays utilize the PCF8574A IC Chip. The Datasheet is HERE: [[file:Pcf8574a.pdf]]

The modules used on these displays may also be used for general-purpose 8-bit I/O expanders. A module with the address pins available is [http://www.yourduino.com/sunshop/index.php?l=product_detail&p=484 HERE]  These I2C interface displays have a built-in ADDRESS. If you try to run a display and '''''there is no response or nothing is displayed you may have the wrong address''''' in the code you are using. You can run the I2C ADDRESS SCANNER (Bottom of this page) on your Arduino to check the address on your display if necessary. For LOTS of detailed technical information about I2C Interfaces see [http://gammon.com.au/i2c THIS ]from Nick Gammon.

===WHY THE I2C (IIC) TYPE LCD DISPLAY?===
To use this type LCD directly with Arduino, you would need 6 pins: RS, EN, D7, D6, D5, and D4 to talk to the LCD. If you are doing more than a simple project, you may be out of pins using a normal LCD shield. With this I2C interface LCD module, you only need 2 lines (I2C) to display information. If you already have I2C devices in your project, this LCD module actually uses no more pins at all. More [http://en.wikipedia.org/wiki/I2C information about I2C/TWI (Wikipedia)] This unit connects with 4 wires including Vcc and Gnd. It is easiest with a 4-wire cable that plugs into the [/SensorShield Sensor Shield] communications connector or directly to a [https://arduinoinfo.mywikis.net/wiki/YourDuino-RoboRED YourDuino RoboRED] (UNO Compatible: [https://arduinoinfo.mywikis.net/wiki/YourDuino-RoboRED See it HERE (click))..]   But you can wire it directly yourself if needed: There are 4 pins on the display.. (see photo below) 
<BR CLEAR=ALL>
[[Image:4-pinCable-Pinout-500.jpg]] 
[[Image:YwRobotLCD-CU-450.jpg]]

{| class="wikitable" style="color: #006699; border: 2px solid darkgray; <!-- Widths are % of the AVAILABLE SCREEN WIDTH  style="border-collapse:collapse"  -->}
| 
|

UNO
|
MEGA
|-
|
SDA
|
Analog 4
|
Pin 20
|-
|
SCL
|
Analog 5
|
Pin 21
|}

On most Arduino boards, SDA (data line) is on analog input pin 4, and SCL (clock line) is on analog input pin 5. On the newer Arduino UNO (The "V3" pinout), the SCL and SDA pins are '''''also''''' on two new leftmost top pins. The YourDuino RoboRED has those pins and also a nice 4-pin connector arranged exactly like the LCD display pins.  On the Arduino Mega, SDA is digital pin 20 and SCL is pin 21.  NOTE: The Blue Potentiometer (Photo) adjusts '''''Contrast.''''' If you don't see any characters, adjust it. Start clockwise and back down to where the characters are bright and the background does not have boxes behind the characters.  

[/PROJECT-Temp-Humidity-Display See a LCD used in the Temperature-Humidity project.]

===LiquidCrystal_I2C Library Support Functions===

See the "Docs" folder within the Library folder. There are many advanced functions.   Below are Example Software Sketches for different displays. They will display characters you type on the Serial Monitor screen on the LCD. NOTE: Line 1 only is correct when writing a long sequence of characters. The characters fill the first line and continue on the third, due to the way the LCD internal addressing works. So this is "normal" and has to do with the LCD hardware. Usually you will set the cursor position before writing characters. (Details in the document linked at the end of this page, if you want them.)  (Cut and paste these examples into a blank page on the Arduino IDE).   
<span id="v1"> </span>


'''I2C LCD DISPLAY VERSION 1:'''
<BR CLEAR=ALL>
[[Image:LCD-A0A1A2.jpg|LCD-A0A1A2.jpg]]

===Example Software Sketch for 2 line 16 character Displays:===

(NOTE: for displays with backpack interface labelled "YwRobot Arduino LCM1602 IIC V1") See photo farther Above.  

(NOTE: Also for displays with backpack interface labelled "A0 A1 A2" photo: above).  

(NOTE: Most displays use I2C Adress 0x27 but '''a FEW (Including those labelled "MH" ) use 0x3F''' (Change in code below) 
 
 <span style="color: #434F54">/* YourDuino.com Example Software Sketch</span>
 <span style="color: #434F54"> 16 character 2 line I2C Display</span>
 <span style="color: #434F54"> Backpack Interface labelled "A0 A1 A2" at lower right.</span>
 <span style="color: #434F54"> ..and</span>
 <span style="color: #434F54"> Backpack Interface labelled "YwRobot Arduino LCM1602 IIC V1"</span>
 <span style="color: #434F54"> MOST use address 0x27, a FEW use 0x3F</span>
 <span style="color: #434F54"> terry@yourduino.com */</span>
 
 <span style="color: #434F54">/*-----( Import needed libraries )-----*/</span>
 #include <<span style="color: #D35400">Wire</span>.h>  <span style="color: #434F54">// Comes with Arduino IDE</span>
 <span style="color: #434F54">// Get the LCD I2C Library here: </span>
 <span style="color: #434F54">// https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads</span>
 <span style="color: #434F54">// Move any other LCD libraries to another folder or delete them</span>
 <span style="color: #434F54">// See Library "Docs" folder for possible commands etc.</span>
 #include <<span style="color: #D35400">'''LiquidCrystal_I2C'''</span>.h>
 
 <span style="color: #434F54">/*-----( Declare Constants )-----*/</span>
 <span style="color: #434F54">/*-----( Declare objects )-----*/</span>
 <span style="color: #434F54">// set the LCD address to 0x27 for a 16 chars 2 line display</span>
 <span style="color: #434F54">// A FEW use address 0x3F</span>
 <span style="color: #434F54">// Set the pins on the I2C chip used for LCD connections:</span>
 <span style="color: #434F54">//                    addr, en,rw,rs,d4,d5,d6,d7,bl,blpol</span>
 <span style="color: #D35400">'''LiquidCrystal_I2C'''</span> lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);  <span style="color: #434F54">// Set the LCD I2C address</span>
 
 <span style="color: #434F54">/*-----( Declare Variables )-----*/</span>
 <span style="color: #434F54">//NONE</span>
 
 <span style="color: #00979C">void</span> <span style="color: #5E6D03">setup</span>()   <span style="color: #434F54">/*----( SETUP: RUNS ONCE )----*/</span>
 {
   <span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">begin</span>(9600);  <span style="color: #434F54">// Used to type in characters</span>
 
   lcd.<span style="color: #D35400">begin</span>(16,2);   <span style="color: #434F54">// initialize the lcd for 16 chars 2 lines, turn on backlight</span>
 
 <span style="color: #434F54">// ------- Quick 3 blinks of backlight  -------------</span>
   <span style="color: #5E6D03">for</span>(<span style="color: #00979C">int</span> i = 0; i< 3; i++)
   {
     lcd.backlight();
     <span style="color: #D35400">delay</span>(250);
     lcd.noBacklight();
     <span style="color: #D35400">delay</span>(250);
   }
   lcd.backlight(); <span style="color: #434F54">// finish with backlight on  </span>
 
 <span style="color: #434F54">//-------- Write characters on the display ------------------</span>
 <span style="color: #434F54">// NOTE: Cursor Position: (CHAR, LINE) start at 0  </span>
   lcd.setCursor(0,0); <span style="color: #434F54">//Start at character 4 on line 0</span>
   lcd.<span style="color: #D35400">print</span>(<span style="color: #006699">"Hello, world!"</span>);
   <span style="color: #D35400">delay</span>(1000);
   lcd.setCursor(0,1);
   lcd.<span style="color: #D35400">print</span>(<span style="color: #006699">"HI!YourDuino.com"</span>);
   <span style="color: #D35400">delay</span>(8000);
 
 <span style="color: #434F54">// Wait and then tell user they can start the Serial Monitor and type in characters to</span>
 <span style="color: #434F54">// Display. (Set Serial Monitor option to "No Line Ending")</span>
   lcd.<span style="color: #D35400">clear</span>();
   lcd.setCursor(0,0); <span style="color: #434F54">//Start at character 0 on line 0</span>
   lcd.<span style="color: #D35400">print</span>(<span style="color: #006699">"Use Serial Mon"</span>);
   lcd.setCursor(0,1);
   lcd.<span style="color: #D35400">print</span>(<span style="color: #006699">"Type to display"</span>);
 
 
 }<span style="color: #434F54">/*--(end setup )---*/</span>
 
 
 <span style="color: #00979C">void</span> <span style="color: #5E6D03">loop</span>()   <span style="color: #434F54">/*----( LOOP: RUNS CONSTANTLY )----*/</span>
 {
   {
     <span style="color: #434F54">// when characters arrive over the serial port...</span>
     <span style="color: #5E6D03">if</span> (<span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">available</span>()) {
       <span style="color: #434F54">// wait a bit for the entire message to arrive</span>
       <span style="color: #D35400">delay</span>(100);
       <span style="color: #434F54">// clear the screen</span>
       lcd.<span style="color: #D35400">clear</span>();
       <span style="color: #434F54">// read all the available characters</span>
       <span style="color: #5E6D03">while</span> (<span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">available</span>() > 0) {
         <span style="color: #434F54">// display each character to the LCD</span>
         lcd.<span style="color: #D35400">write</span>(<span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">read</span>());
       }
     }
   }
 
 }<span style="color: #434F54">/* --(end main loop )-- */</span>
 
 
 <span style="color: #434F54">/* ( THE END ) */</span>

===Example Software Sketch for 4 line 20 character Displays:===

(NOTE: for displays with backpack interface labelled "YwRobot Arduino LCM1602 IIC V1")  (NOTE: Also for displays with backpack interface labelled "A0 A1 A2" photo: right).  (NOTE: Most displays use I2C Adress 0x27 but '''a FEW (Including those labelled "MH" ) use 0x3F''' (Change in code below) 
 
 <span style="color: #7E7E7E">/* YourDuino.com Example Software Sketch</span>
 <span style="color: #7E7E7E"> 20 character 4 line I2C Display</span>
 <span style="color: #7E7E7E"> Backpack Interface labelled "YwRobot Arduino LCM1602 IIC V1"</span>
 <span style="color: #7E7E7E"> Connect Vcc and Ground, SDA to A4, SCL to A5 on Arduino</span>
 <span style="color: #7E7E7E"> terry@yourduino.com */</span>
 
 <span style="color: #7E7E7E">/*-----( Import needed libraries )-----*/</span>
 #include <<span style="color: #CC6600">Wire</span>.h>  <span style="color: #7E7E7E">// Comes with Arduino IDE</span>
 <span style="color: #7E7E7E">// Get the LCD I2C Library here: </span>
 <span style="color: #7E7E7E">// https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads</span>
 <span style="color: #7E7E7E">// Move any other LCD libraries to another folder or delete them</span>
 <span style="color: #7E7E7E">// See Library "Docs" folder for possible commands etc.</span>
 #include <<span style="color: #CC6600">LiquidCrystal_I2C</span>.h>
 
 <span style="color: #7E7E7E">/*-----( Declare Constants )-----*/</span>
 <span style="color: #7E7E7E">/*-----( Declare objects )-----*/</span>
 <span style="color: #7E7E7E">// set the LCD address to 0x27 for a 20 chars 4 line display</span>
 <span style="color: #7E7E7E">// Set the pins on the I2C chip used for LCD connections:</span>
 <span style="color: #7E7E7E">//                    addr, en,rw,rs,d4,d5,d6,d7,bl,blpol</span>
 <span style="color: #CC6600">LiquidCrystal_I2C</span> lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);  <span style="color: #7E7E7E">// Set the LCD I2C address</span>
 
 
 <span style="color: #7E7E7E">/*-----( Declare Variables )-----*/</span>
 
 
 <span style="color: #CC6600">void</span> <span style="color: #CC6600">'''setup'''</span>()   <span style="color: #7E7E7E">/*----( SETUP: RUNS ONCE )----*/</span>
 {
   <span style="color: #CC6600">'''Serial'''</span>.<span style="color: #CC6600">begin</span>(9600);  <span style="color: #7E7E7E">// Used to type in characters</span>
 
   lcd.<span style="color: #CC6600">begin</span>(20,4);         <span style="color: #7E7E7E">// initialize the lcd for 20 chars 4 lines, turn on backlight</span>
 
 <span style="color: #7E7E7E">// ------- Quick 3 blinks of backlight  -------------</span>
   <span style="color: #CC6600">for</span>(<span style="color: #CC6600">int</span> i = 0; i< 3; i++)
   {
     lcd.backlight();
     <span style="color: #CC6600">delay</span>(250);
     lcd.noBacklight();
     <span style="color: #CC6600">delay</span>(250);
   }
   lcd.backlight(); <span style="color: #7E7E7E">// finish with backlight on  </span>
 
 <span style="color: #7E7E7E">//-------- Write characters on the display ------------------</span>
   <span style="color: #7E7E7E">// NOTE: Cursor Position: Lines and Characters start at 0  </span>
   lcd.<span style="color: #CC6600">setCursor</span>(3,0); <span style="color: #7E7E7E">//Start at character 4 on line 0</span>
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"Hello, world!"</span>);
   <span style="color: #CC6600">delay</span>(1000);
   lcd.<span style="color: #CC6600">setCursor</span>(2,1);
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"From YourDuino"</span>);
   <span style="color: #CC6600">delay</span>(1000);
   lcd.<span style="color: #CC6600">setCursor</span>(0,2);
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"20 by 4 Line Display"</span>);
   lcd.<span style="color: #CC6600">setCursor</span>(0,3);
   <span style="color: #CC6600">delay</span>(2000);
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"http://YourDuino.com"</span>);
   <span style="color: #CC6600">delay</span>(8000);
   <span style="color: #7E7E7E">// Wait and then tell user they can start the Serial Monitor and type in characters to</span>
   <span style="color: #7E7E7E">// Display. (Set Serial Monitor option to "No Line Ending")</span>
   lcd.<span style="color: #CC6600">setCursor</span>(0,0); <span style="color: #7E7E7E">//Start at character 0 on line 0</span>
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"Start Serial Monitor"</span>);
   lcd.<span style="color: #CC6600">setCursor</span>(0,1);
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"Type chars 2 display"</span>);
 
 
 }<span style="color: #7E7E7E">/*--(end setup )---*/</span>
 
 
 <span style="color: #CC6600">void</span> <span style="color: #CC6600">'''loop'''</span>()   <span style="color: #7E7E7E">/*----( LOOP: RUNS CONSTANTLY )----*/</span>
 {
   {
     <span style="color: #7E7E7E">// when characters arrive over the serial port...</span>
     <span style="color: #CC6600">if</span> (<span style="color: #CC6600">'''Serial'''</span>.<span style="color: #CC6600">available</span>()) {
       <span style="color: #7E7E7E">// wait a bit for the entire message to arrive</span>
       <span style="color: #CC6600">delay</span>(100);
       <span style="color: #7E7E7E">// clear the screen</span>
       lcd.<span style="color: #CC6600">clear</span>();
       <span style="color: #7E7E7E">// read all the available characters</span>
       <span style="color: #CC6600">while</span> (<span style="color: #CC6600">'''Serial'''</span>.<span style="color: #CC6600">available</span>() > 0) {
         <span style="color: #7E7E7E">// display each character to the LCD</span>
         lcd.<span style="color: #CC6600">write</span>(<span style="color: #CC6600">'''Serial'''</span>.<span style="color: #CC6600">read</span>());
       }
     }
   }
 
 }<span style="color: #7E7E7E">/* --(end main loop )-- */</span>
 
 
 <span style="color: #7E7E7E">/* ( THE END ) */</span>
 
 
----
<span id="v2"> </span>
===I2C LCD DISPLAY VERSION 2:===

[[Image:LCD-Arduino-IIC-LCD-GY-LCD-V1.jpg|LCD-Arduino-IIC-LCD-GY-LCD-V1.jpg]]
Marked "Arduino-IIC-LCD GY-LCD-V1"  NOTE: The wire connections are in a different order! See the labels on the PC Board.  

===NEW TYPE 4 line 20 character Displays: Example Software Sketch===
 
 <span style="color: #7E7E7E">/* YourDuino.com Example Software Sketch</span>
 <span style="color: #7E7E7E"> 20 character 4 line I2C Display</span>
 <span style="color: #7E7E7E"> Backpack Interface labelled "LCM1602 IIC  A0 A1 A2"</span>
 <span style="color: #7E7E7E"> terry@yourduino.com */</span>
 
 <span style="color: #7E7E7E">/*-----( Import needed libraries )-----*/</span>
 #include <<span style="color: #CC6600">Wire</span>.h>  <span style="color: #7E7E7E">// Comes with Arduino IDE</span>
 <span style="color: #7E7E7E">// Get the LCD I2C Library here: </span>
 <span style="color: #7E7E7E">// https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads</span>
 <span style="color: #7E7E7E">// Move any other LCD libraries to another folder or delete them</span>
 <span style="color: #7E7E7E">// See Library "Docs" folder for possible commands etc.</span>
 #include <<span style="color: #CC6600">LiquidCrystal_I2C</span>.h>
 
 <span style="color: #7E7E7E">/*-----( Declare Constants )-----*/</span>
 <span style="color: #7E7E7E">//none</span>
 <span style="color: #7E7E7E">/*-----( Declare objects )-----*/</span>
 <span style="color: #7E7E7E">// set the LCD address to 0x27 for a 20 chars 4 line display</span>
 <span style="color: #7E7E7E">// Set the pins on the I2C chip used for LCD connections:</span>
 <span style="color: #7E7E7E">//                    addr, en,rw,rs,d4,d5,d6,d7,bl,blpol</span>
 <span style="color: #CC6600">LiquidCrystal_I2C</span> lcd(0x20, 4, 5, 6, 0, 1, 2, 3, 7, NEGATIVE);  <span style="color: #7E7E7E">// Set the LCD I2C address</span>
 
 
 <span style="color: #7E7E7E">/*-----( Declare Variables )-----*/</span>
 <span style="color: #7E7E7E">//none</span>
 
 <span style="color: #CC6600">void</span> <span style="color: #CC6600">'''setup'''</span>()   <span style="color: #7E7E7E">/*----( SETUP: RUNS ONCE )----*/</span>
 {
   <span style="color: #CC6600">'''Serial'''</span>.<span style="color: #CC6600">begin</span>(9600);  <span style="color: #7E7E7E">// Used to type in characters</span>
 
   lcd.<span style="color: #CC6600">begin</span>(20,4);         <span style="color: #7E7E7E">// initialize the lcd for 20 chars 4 lines</span>
 
 <span style="color: #7E7E7E">// NOTE: Cursor Position: CHAR, LINE) start at 0  </span>
   lcd.<span style="color: #CC6600">setCursor</span>(3,0); <span style="color: #7E7E7E">//Start at character 4 on line 0</span>
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"Hello, world!"</span>);
   <span style="color: #CC6600">delay</span>(1000);
   lcd.<span style="color: #CC6600">setCursor</span>(2,1);
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"From YourDuino"</span>);
   <span style="color: #CC6600">delay</span>(1000);
   lcd.<span style="color: #CC6600">setCursor</span>(0,2);
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"20 by 4 Line Display"</span>);
   lcd.<span style="color: #CC6600">setCursor</span>(0,3);
   <span style="color: #CC6600">delay</span>(2000);
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"http://YourDuino.com"</span>);
   <span style="color: #CC6600">delay</span>(8000);
 <span style="color: #7E7E7E">// Wait and then tell user they can start the Serial Monitor and type in characters to</span>
 <span style="color: #7E7E7E">// Display. (Set Serial Monitor option to "No Line Ending")</span>
   lcd.<span style="color: #CC6600">setCursor</span>(0,0); <span style="color: #7E7E7E">//Start at character 0 on line 0</span>
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"Start Serial Monitor"</span>);
   lcd.<span style="color: #CC6600">setCursor</span>(0,1);
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"Type chars 2 display"</span>);
 
 
 }<span style="color: #7E7E7E">/*--(end setup )---*/</span>
 
 
 <span style="color: #CC6600">void</span> <span style="color: #CC6600">'''loop'''</span>()   <span style="color: #7E7E7E">/*----( LOOP: RUNS CONSTANTLY )----*/</span>
 {
   {
     <span style="color: #7E7E7E">// when characters arrive over the serial port...</span>
     <span style="color: #CC6600">if</span> (<span style="color: #CC6600">'''Serial'''</span>.<span style="color: #CC6600">available</span>()) {
       <span style="color: #7E7E7E">// wait a bit for the entire message to arrive</span>
       <span style="color: #CC6600">delay</span>(100);
       <span style="color: #7E7E7E">// clear the screen</span>
       lcd.<span style="color: #CC6600">clear</span>();
       <span style="color: #7E7E7E">// read all the available characters</span>
       <span style="color: #CC6600">while</span> (<span style="color: #CC6600">'''Serial'''</span>.<span style="color: #CC6600">available</span>() > 0) {
         <span style="color: #7E7E7E">// display each character to the LCD</span>
         lcd.<span style="color: #CC6600">write</span>(<span style="color: #CC6600">'''Serial'''</span>.<span style="color: #CC6600">read</span>());
       }
     }
   }
 
 }<span style="color: #7E7E7E">/* --(end main loop )-- */</span>
 
 
 <span style="color: #7E7E7E">/* ( THE END ) */</span>
 
 
----
<span id="v3"> </span>
===I2C LCD DISPLAY VERSION 3:===
This has Yet Another I2C board type marked "LCM1602 IIC A0 A1 A2" (Photo)</span>  '''NOTE:''' Some of this type board come with the A0 A1 A2 connections (See photo) that are NOT bridged with solder as in the photo. Those will have address 0x27 not address 0x20. For that version you need to change the sketch example below.  
 LiquidCrystal_I2C lcd(0x20, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);
 MUST BE CHANGED TO:
 LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);
[[file:LCD-20x4-New3-800.jpg]]  
<BR CLEAR=ALL>
You need the same new library in the section above.  Here's an example Software Sketch that works with this display. Copy this and paste into blank Arduino IDE window. Verify (Need the library above installed), then upload. 
 
 <span style="color: #7E7E7E">/* YourDuino.com Example Software Sketch</span>
 <span style="color: #7E7E7E"> 20 character 4 line I2C Display</span>
 <span style="color: #7E7E7E"> Backpack Interface labelled "LCM1602 IIC  A0 A1 A2"</span>
 <span style="color: #7E7E7E"> terry@yourduino.com */</span>
 
 <span style="color: #7E7E7E">/*-----( Import needed libraries )-----*/</span>
 #include <<span style="color: #CC6600">Wire</span>.h>  <span style="color: #7E7E7E">// Comes with Arduino IDE</span>
 <span style="color: #7E7E7E">// Get the LCD I2C Library here: </span>
 <span style="color: #7E7E7E">// https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads</span>
 <span style="color: #7E7E7E">// Move any other LCD libraries to another folder or delete them</span>
 <span style="color: #7E7E7E">// See Library "Docs" folder for possible commands etc.</span>
 #include <<span style="color: #CC6600">LiquidCrystal_I2C</span>.h>
 
 <span style="color: #7E7E7E">/*-----( Declare Constants )-----*/</span>
 <span style="color: #7E7E7E">//none</span>
 <span style="color: #7E7E7E">/*-----( Declare objects )-----*/</span>
 <span style="color: #7E7E7E">// set the LCD address to 0x20 for a 20 chars 4 line display</span>
 <span style="color: #7E7E7E">// Set the pins on the I2C chip used for LCD connections:</span>
 <span style="color: #7E7E7E">//                    addr, en,rw,rs,d4,d5,d6,d7,bl,blpol</span>
 <span style="color: #CC6600">LiquidCrystal_I2C</span> lcd(0x20, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);  <span style="color: #7E7E7E">// Set the LCD I2C address</span>
 
 
 <span style="color: #7E7E7E">/*-----( Declare Variables )-----*/</span>
 <span style="color: #7E7E7E">//none</span>
 
 <span style="color: #CC6600">void</span> <span style="color: #CC6600">'''setup'''</span>()   <span style="color: #7E7E7E">/*----( SETUP: RUNS ONCE )----*/</span>
 {
   <span style="color: #CC6600">'''Serial'''</span>.<span style="color: #CC6600">begin</span>(9600);  <span style="color: #7E7E7E">// Used to type in characters</span>
 
   lcd.<span style="color: #CC6600">begin</span>(20,4);         <span style="color: #7E7E7E">// initialize the lcd for 20 chars 4 lines and turn on backlight</span>
 
 <span style="color: #7E7E7E">// ------- Quick 3 blinks of backlight  -------------</span>
   <span style="color: #CC6600">for</span>(<span style="color: #CC6600">int</span> i = 0; i< 3; i++)
   {
     lcd.backlight();
     <span style="color: #CC6600">delay</span>(250);
     lcd.noBacklight();
     <span style="color: #CC6600">delay</span>(250);
   }
   lcd.backlight(); <span style="color: #7E7E7E">// finish with backlight on  </span>
 
 <span style="color: #7E7E7E">//-------- Write characters on the display ----------------</span>
 <span style="color: #7E7E7E">// NOTE: Cursor Position: CHAR, LINE) start at 0  </span>
   lcd.<span style="color: #CC6600">setCursor</span>(3,0); <span style="color: #7E7E7E">//Start at character 4 on line 0</span>
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"Hello, world!"</span>);
   <span style="color: #CC6600">delay</span>(1000);
   lcd.<span style="color: #CC6600">setCursor</span>(2,1);
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"From YourDuino"</span>);
   <span style="color: #CC6600">delay</span>(1000);
   lcd.<span style="color: #CC6600">setCursor</span>(0,2);
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"20 by 4 Line Display"</span>);
   lcd.<span style="color: #CC6600">setCursor</span>(0,3);
   <span style="color: #CC6600">delay</span>(2000);
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"http://YourDuino.com"</span>);
   <span style="color: #CC6600">delay</span>(8000);
 <span style="color: #7E7E7E">// Wait and then tell user they can start the Serial Monitor and type in characters to</span>
 <span style="color: #7E7E7E">// Display. (Set Serial Monitor option to "No Line Ending")</span>
   lcd.<span style="color: #CC6600">setCursor</span>(0,0); <span style="color: #7E7E7E">//Start at character 0 on line 0</span>
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"Start Serial Monitor"</span>);
   lcd.<span style="color: #CC6600">setCursor</span>(0,1);
   lcd.<span style="color: #CC6600">print</span>(<span style="color: #006699">"Type chars 2 display"</span>);
 
 
 }<span style="color: #7E7E7E">/*--(end setup )---*/</span>
 
 
 <span style="color: #CC6600">void</span> <span style="color: #CC6600">'''loop'''</span>()   <span style="color: #7E7E7E">/*----( LOOP: RUNS CONSTANTLY )----*/</span>
 {
   {
     <span style="color: #7E7E7E">// when characters arrive over the serial port...</span>
     <span style="color: #CC6600">if</span> (<span style="color: #CC6600">'''Serial'''</span>.<span style="color: #CC6600">available</span>()) {
       <span style="color: #7E7E7E">// wait a bit for the entire message to arrive</span>
       <span style="color: #CC6600">delay</span>(100);
       <span style="color: #7E7E7E">// clear the screen</span>
       lcd.<span style="color: #CC6600">clear</span>();
       <span style="color: #7E7E7E">// read all the available characters</span>
       <span style="color: #CC6600">while</span> (<span style="color: #CC6600">'''Serial'''</span>.<span style="color: #CC6600">available</span>() > 0) {
         <span style="color: #7E7E7E">// display each character to the LCD</span>
         lcd.<span style="color: #CC6600">write</span>(<span style="color: #CC6600">'''Serial'''</span>.<span style="color: #CC6600">read</span>());
       }
     }
   }
 
 }<span style="color: #7E7E7E">/* --(end main loop )-- */</span>
 
 
 <span style="color: #7E7E7E">/* ( THE END ) */</span>
 
<span id="scan"> </span>

===I2C ADDRESS SCANNER FOR ARDUINO/YOURDUINO:===
You can scan for the I2C address used by your display. Connect your display (See connection info at top of this page). Then upload the following sketch to your Arduino. Click on "Serial Monitor at upper right. '''Set the Speed (lower right pulldown) to 115200'''. Push the Reset button on your Arduino and see the results. The results should look like this (address changes): 
<pre> 
 I2C scanner. Scanning ...
 Found address: 39 (0x27)
 Done.
 Found 1 device(s).
 </pre> 
Copy and Paste this sketch (Thanks Nick Gammon!) into a blank Arduino IDE window: 
 
 
 <span style="color: #434F54">// I2C Scanner</span>
 <span style="color: #434F54">// Written by Nick Gammon</span>
 <span style="color: #434F54">// Date: 20th April 2011</span>
 
 #include <<span style="color: #D35400">Wire</span>.h>
 
 <span style="color: #00979C">void</span> <span style="color: #5E6D03">setup</span>() {
   <span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">begin</span> (115200);
 
   <span style="color: #434F54">// Leonardo: wait for serial port to connect</span>
   <span style="color: #5E6D03">while</span> (!<span style="color: #D35400">'''Serial'''</span>)
     {
     }
 
   <span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">println</span> ();
   <span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">println</span> (<span style="color: #006699">"I2C scanner. Scanning ..."</span>);
   <span style="color: #00979C">byte</span> count = 0;
 
   <span style="color: #D35400">Wire</span>.<span style="color: #D35400">begin</span>();
   <span style="color: #5E6D03">for</span> (<span style="color: #00979C">byte</span> i = 8; i < 120; i++)
   {
     <span style="color: #D35400">Wire</span>.<span style="color: #D35400">beginTransmission</span> (i);
     <span style="color: #5E6D03">if</span> (<span style="color: #D35400">Wire</span>.<span style="color: #D35400">endTransmission</span> () == 0)
       {
       <span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">print</span> (<span style="color: #006699">"Found address: "</span>);
       <span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">print</span> (i, <span style="color: #00979C">DEC</span>);
       <span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">print</span> (<span style="color: #006699">" (0x"</span>);
       <span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">print</span> (i, <span style="color: #00979C">HEX</span>);
       <span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">println</span> (<span style="color: #006699">")"</span>);
       count++;
       <span style="color: #D35400">delay</span> (1);  <span style="color: #434F54">// maybe unneeded?</span>
       } <span style="color: #434F54">// end of good response</span>
   } <span style="color: #434F54">// end of for loop</span>
   <span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">println</span> (<span style="color: #006699">"Done."</span>);
   <span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">print</span> (<span style="color: #006699">"Found "</span>);
   <span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">print</span> (count, <span style="color: #00979C">DEC</span>);
   <span style="color: #D35400">'''Serial'''</span>.<span style="color: #D35400">println</span> (<span style="color: #006699">" device(s)."</span>);
 }  <span style="color: #434F54">// end of setup</span>
 
 <span style="color: #00979C">void</span> <span style="color: #5E6D03">loop</span>() {}

===CHANGING I2C ADDRESSES:===
  SOME I2C interfaces have pins (or solder pads) that can be changed to change the address. They are usually labelled A0-A1-A2 . Here's the way addresses change from a default 0x27 with if you connect address pads together. (1 = Not Connected. 0 = Connected):  
  
{| class="wikitable" style="color: #006699; border: 2px solid darkgray; <!-- Widths are % of the AVAILABLE SCREEN WIDTH  style="border-collapse:collapse"  -->"
|
A0
|
A1
|
A2
|
HEX Address
|-
|
1
|
1
|
1
|
0x27
|-
|
0
|
1
|
1
|
0x26
|-
|
1
|
0
|
1
|
0x25
|-
|
0
|
0
|
1
|
0x24
|-
|
1
|
1
|
0
|
0x23
|-
|
0
|
1
|
0
|
0x22
|-
|
1
|
0
|
0
|
0x21
|-
|
0
|
0
|
0
|
0x20
|}

If you make a change use the I2C Address Scanner to confirm it...    Detailed information about LCD displays from Donald Weiman  (weimandn@alfredstate.edu)
[[file:LCD_Addressing.pdf ]]
 
'''MORE INFORMATION ABOUT THE I2C "BACKPACK" USED ON THESE DISPLAYS:'''  Schematic Diagram: [[Image:Ic2-BackPackSchematic-1.jpg]]
[[file:Pcf8574a.pdf]] 


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