Replaced LiquidCrystal_I2C lib with newer version which was reported to have worked on the arduino forum - ref http://forum.arduino.cc/index.php?topic=310743.msg2186521#msg2186521

This commit is contained in:
Roger Clark 2015-04-15 21:08:01 +10:00
parent f92015b9f4
commit 14b59151dd
15 changed files with 384 additions and 311 deletions

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@ -1,7 +1,10 @@
// LiquidCrystal_I2C V2.0
#include "LiquidCrystal_I2C.h" #include "LiquidCrystal_I2C.h"
#include <inttypes.h> #include <inttypes.h>
#include <Arduino.h> #include "Wire.h"
#include <Wire.h> #include "Arduino.h"
// When the display powers up, it is configured as follows: // When the display powers up, it is configured as follows:
// //
@ -22,32 +25,40 @@
// can't assume that its in that state when a sketch starts (and the // can't assume that its in that state when a sketch starts (and the
// LiquidCrystal constructor is called). // LiquidCrystal constructor is called).
LiquidCrystal_I2C::LiquidCrystal_I2C(uint8_t lcd_addr, uint8_t lcd_cols, uint8_t lcd_rows, uint8_t charsize) LiquidCrystal_I2C::LiquidCrystal_I2C(uint8_t lcd_Addr,uint8_t lcd_cols,uint8_t lcd_rows)
{ {
_addr = lcd_addr; _Addr = lcd_Addr;
_cols = lcd_cols; _cols = lcd_cols;
_rows = lcd_rows; _rows = lcd_rows;
_charsize = charsize; _backlightval = LCD_NOBACKLIGHT;
_backlightval = LCD_BACKLIGHT;
} }
void LiquidCrystal_I2C::begin() { void LiquidCrystal_I2C::init(){
init_priv();
}
void LiquidCrystal_I2C::init_priv()
{
Wire.begin(); Wire.begin();
_displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS; _displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;
begin(_cols, _rows);
}
if (_rows > 1) { void LiquidCrystal_I2C::begin(uint8_t cols, uint8_t lines, uint8_t dotsize) {
if (lines > 1) {
_displayfunction |= LCD_2LINE; _displayfunction |= LCD_2LINE;
} }
_numlines = lines;
// for some 1 line displays you can select a 10 pixel high font // for some 1 line displays you can select a 10 pixel high font
if ((_charsize != 0) && (_rows == 1)) { if ((dotsize != 0) && (lines == 1)) {
_displayfunction |= LCD_5x10DOTS; _displayfunction |= LCD_5x10DOTS;
} }
// SEE PAGE 45/46 FOR INITIALIZATION SPECIFICATION! // SEE PAGE 45/46 FOR INITIALIZATION SPECIFICATION!
// according to datasheet, we need at least 40ms after power rises above 2.7V // according to datasheet, we need at least 40ms after power rises above 2.7V
// before sending commands. Arduino can turn on way befer 4.5V so we'll wait 50 // before sending commands. Arduino can turn on way befer 4.5V so we'll wait 50
delay(50); delayMicroseconds(50000);
// Now we pull both RS and R/W low to begin commands // Now we pull both RS and R/W low to begin commands
expanderWrite(_backlightval); // reset expanderand turn backlight off (Bit 8 =1) expanderWrite(_backlightval); // reset expanderand turn backlight off (Bit 8 =1)
@ -58,19 +69,20 @@ void LiquidCrystal_I2C::begin() {
// figure 24, pg 46 // figure 24, pg 46
// we start in 8bit mode, try to set 4 bit mode // we start in 8bit mode, try to set 4 bit mode
write4bits(0x03 << 4); write4bits(0x03);
delayMicroseconds(4500); // wait min 4.1ms delayMicroseconds(4500); // wait min 4.1ms
// second try // second try
write4bits(0x03 << 4); write4bits(0x03);
delayMicroseconds(4500); // wait min 4.1ms delayMicroseconds(4500); // wait min 4.1ms
// third go! // third go!
write4bits(0x03 << 4); write4bits(0x03);
delayMicroseconds(150); delayMicroseconds(150);
// finally, set to 4-bit interface // finally, set to 4-bit interface
write4bits(0x02 << 4); write4bits(0x02);
// set # lines, font size, etc. // set # lines, font size, etc.
command(LCD_FUNCTIONSET | _displayfunction); command(LCD_FUNCTIONSET | _displayfunction);
@ -89,8 +101,11 @@ void LiquidCrystal_I2C::begin() {
command(LCD_ENTRYMODESET | _displaymode); command(LCD_ENTRYMODESET | _displaymode);
home(); home();
} }
/********** high level commands, for the user! */ /********** high level commands, for the user! */
void LiquidCrystal_I2C::clear(){ void LiquidCrystal_I2C::clear(){
command(LCD_CLEARDISPLAY);// clear display, set cursor position to zero command(LCD_CLEARDISPLAY);// clear display, set cursor position to zero
@ -104,8 +119,8 @@ void LiquidCrystal_I2C::home(){
void LiquidCrystal_I2C::setCursor(uint8_t col, uint8_t row){ void LiquidCrystal_I2C::setCursor(uint8_t col, uint8_t row){
int row_offsets[] = { 0x00, 0x40, 0x14, 0x54 }; int row_offsets[] = { 0x00, 0x40, 0x14, 0x54 };
if (row > _rows) { if ( row > _numlines ) {
row = _rows-1; // we count rows starting w/0 row = _numlines-1; // we count rows starting w/0
} }
command(LCD_SETDDRAMADDR | (col + row_offsets[row])); command(LCD_SETDDRAMADDR | (col + row_offsets[row]));
} }
@ -193,6 +208,8 @@ void LiquidCrystal_I2C::backlight(void) {
expanderWrite(0); expanderWrite(0);
} }
/*********** mid level commands, for sending data/cmds */ /*********** mid level commands, for sending data/cmds */
inline void LiquidCrystal_I2C::command(uint8_t value) { inline void LiquidCrystal_I2C::command(uint8_t value) {
@ -201,15 +218,17 @@ inline void LiquidCrystal_I2C::command(uint8_t value) {
inline size_t LiquidCrystal_I2C::write(uint8_t value) { inline size_t LiquidCrystal_I2C::write(uint8_t value) {
send(value, Rs); send(value, Rs);
return 0;
} }
/************ low level data pushing commands **********/ /************ low level data pushing commands **********/
// write either command or data // write either command or data
void LiquidCrystal_I2C::send(uint8_t value, uint8_t mode) { void LiquidCrystal_I2C::send(uint8_t value, uint8_t mode) {
uint8_t highnib=value&0xf0; uint8_t highnib=value>>4;
uint8_t lownib=(value<<4)&0xf0; uint8_t lownib=value & 0x0F;
write4bits((highnib)|mode); write4bits((highnib)|mode);
write4bits((lownib)|mode); write4bits((lownib)|mode);
} }
@ -220,7 +239,7 @@ void LiquidCrystal_I2C::write4bits(uint8_t value) {
} }
void LiquidCrystal_I2C::expanderWrite(uint8_t _data){ void LiquidCrystal_I2C::expanderWrite(uint8_t _data){
Wire.beginTransmission(_addr); Wire.beginTransmission(_Addr);
Wire.write((int)(_data) | _backlightval); Wire.write((int)(_data) | _backlightval);
Wire.endTransmission(); Wire.endTransmission();
} }
@ -233,14 +252,33 @@ void LiquidCrystal_I2C::pulseEnable(uint8_t _data){
delayMicroseconds(50); // commands need > 37us to settle delayMicroseconds(50); // commands need > 37us to settle
} }
// Alias functions
void LiquidCrystal_I2C::cursor_on(){
cursor();
}
void LiquidCrystal_I2C::cursor_off(){
noCursor();
}
void LiquidCrystal_I2C::blink_on(){
blink();
}
void LiquidCrystal_I2C::blink_off(){
noBlink();
}
void LiquidCrystal_I2C::load_custom_character(uint8_t char_num, uint8_t *rows){ void LiquidCrystal_I2C::load_custom_character(uint8_t char_num, uint8_t *rows){
createChar(char_num, rows); createChar(char_num, rows);
} }
void LiquidCrystal_I2C::setBacklight(uint8_t new_val){ void LiquidCrystal_I2C::setBacklight(uint8_t new_val){
if (new_val) { if(new_val){
backlight(); // turn backlight on backlight(); // turn backlight on
} else { }else{
noBacklight(); // turn backlight off noBacklight(); // turn backlight off
} }
} }
@ -250,3 +288,17 @@ void LiquidCrystal_I2C::printstr(const char c[]){
//it's here so the user sketch doesn't have to be changed //it's here so the user sketch doesn't have to be changed
print(c); print(c);
} }
// unsupported API functions
void LiquidCrystal_I2C::off(){}
void LiquidCrystal_I2C::on(){}
void LiquidCrystal_I2C::setDelay (int cmdDelay,int charDelay) {}
uint8_t LiquidCrystal_I2C::status(){return 0;}
uint8_t LiquidCrystal_I2C::keypad (){return 0;}
uint8_t LiquidCrystal_I2C::init_bargraph(uint8_t graphtype){return 0;}
void LiquidCrystal_I2C::draw_horizontal_graph(uint8_t row, uint8_t column, uint8_t len, uint8_t pixel_col_end){}
void LiquidCrystal_I2C::draw_vertical_graph(uint8_t row, uint8_t column, uint8_t len, uint8_t pixel_row_end){}
void LiquidCrystal_I2C::setContrast(uint8_t new_val){}

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@ -1,8 +1,11 @@
#ifndef FDB_LIQUID_CRYSTAL_I2C_H // LiquidCrystal_I2C V2.0
#define FDB_LIQUID_CRYSTAL_I2C_H
#ifndef LiquidCrystal_I2C_h
#define LiquidCrystal_I2C_h
#include <inttypes.h> #include <inttypes.h>
#include <Print.h> #include "Print.h"
#include <Wire.h>
// commands // commands
#define LCD_CLEARDISPLAY 0x01 #define LCD_CLEARDISPLAY 0x01
@ -43,82 +46,25 @@
#define LCD_5x8DOTS 0x00 #define LCD_5x8DOTS 0x00
// flags for backlight control // flags for backlight control
#define LCD_BACKLIGHT 0x08 #define LCD_BACKLIGHT 0x00
#define LCD_NOBACKLIGHT 0x00 #define LCD_NOBACKLIGHT 0x80
#define En B00000100 // Enable bit #define En B00010000 // Enable bit
#define Rw B00000010 // Read/Write bit #define Rw B00100000 // Read/Write bit
#define Rs B00000001 // Register select bit #define Rs B01000000 // Register select bit
/**
* This is the driver for the Liquid Crystal LCD displays that use the I2C bus.
*
* After creating an instance of this class, first call begin() before anything else.
* The backlight is on by default, since that is the most likely operating mode in
* most cases.
*/
class LiquidCrystal_I2C : public Print { class LiquidCrystal_I2C : public Print {
public: public:
/** LiquidCrystal_I2C(uint8_t lcd_Addr,uint8_t lcd_cols,uint8_t lcd_rows);
* Constructor void begin(uint8_t cols, uint8_t rows, uint8_t charsize = LCD_5x8DOTS );
*
* @param lcd_addr I2C slave address of the LCD display. Most likely printed on the
* LCD circuit board, or look in the supplied LCD documentation.
* @param lcd_cols Number of columns your LCD display has.
* @param lcd_rows Number of rows your LCD display has.
* @param charsize The size in dots that the display has, use LCD_5x10DOTS or LCD_5x8DOTS.
*/
LiquidCrystal_I2C(uint8_t lcd_addr, uint8_t lcd_cols, uint8_t lcd_rows, uint8_t charsize = LCD_5x8DOTS);
/**
* Set the LCD display in the correct begin state, must be called before anything else is done.
*/
void begin();
/**
* Remove all the characters currently shown. Next print/write operation will start
* from the first position on LCD display.
*/
void clear(); void clear();
/**
* Next print/write operation will will start from the first position on the LCD display.
*/
void home(); void home();
/**
* Do not show any characters on the LCD display. Backlight state will remain unchanged.
* Also all characters written on the display will return, when the display in enabled again.
*/
void noDisplay(); void noDisplay();
/**
* Show the characters on the LCD display, this is the normal behaviour. This method should
* only be used after noDisplay() has been used.
*/
void display(); void display();
/**
* Do not blink the cursor indicator.
*/
void noBlink(); void noBlink();
/**
* Start blinking the cursor indicator.
*/
void blink(); void blink();
/**
* Do not show a cursor indicator.
*/
void noCursor(); void noCursor();
/**
* Show a cursor indicator, cursor can blink on not blink. Use the
* methods blink() and noBlink() for changing cursor blink.
*/
void cursor(); void cursor();
void scrollDisplayLeft(); void scrollDisplayLeft();
void scrollDisplayRight(); void scrollDisplayRight();
void printLeft(); void printLeft();
@ -135,30 +81,43 @@ public:
void setCursor(uint8_t, uint8_t); void setCursor(uint8_t, uint8_t);
virtual size_t write(uint8_t); virtual size_t write(uint8_t);
void command(uint8_t); void command(uint8_t);
void init();
inline void blink_on() { blink(); } ////compatibility API function aliases
inline void blink_off() { noBlink(); } void blink_on(); // alias for blink()
inline void cursor_on() { cursor(); } void blink_off(); // alias for noBlink()
inline void cursor_off() { noCursor(); } void cursor_on(); // alias for cursor()
void cursor_off(); // alias for noCursor()
void setBacklight(uint8_t new_val); // alias for backlight() and nobacklight()
void load_custom_character(uint8_t char_num, uint8_t *rows); // alias for createChar()
void printstr(const char[]);
////Unsupported API functions (not implemented in this library)
uint8_t status();
void setContrast(uint8_t new_val);
uint8_t keypad();
void setDelay(int,int);
void on();
void off();
uint8_t init_bargraph(uint8_t graphtype);
void draw_horizontal_graph(uint8_t row, uint8_t column, uint8_t len, uint8_t pixel_col_end);
void draw_vertical_graph(uint8_t row, uint8_t column, uint8_t len, uint8_t pixel_col_end);
// Compatibility API function aliases
void setBacklight(uint8_t new_val); // alias for backlight() and nobacklight()
void load_custom_character(uint8_t char_num, uint8_t *rows); // alias for createChar()
void printstr(const char[]);
private: private:
void init_priv();
void send(uint8_t, uint8_t); void send(uint8_t, uint8_t);
void write4bits(uint8_t); void write4bits(uint8_t);
void expanderWrite(uint8_t); void expanderWrite(uint8_t);
void pulseEnable(uint8_t); void pulseEnable(uint8_t);
uint8_t _addr; uint8_t _Addr;
uint8_t _displayfunction; uint8_t _displayfunction;
uint8_t _displaycontrol; uint8_t _displaycontrol;
uint8_t _displaymode; uint8_t _displaymode;
uint8_t _numlines;
uint8_t _cols; uint8_t _cols;
uint8_t _rows; uint8_t _rows;
uint8_t _charsize;
uint8_t _backlightval; uint8_t _backlightval;
}; };
#endif // FDB_LIQUID_CRYSTAL_I2C_H #endif

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@ -1,11 +0,0 @@
# Installation #
Create a new folder called "LiquidCrystal_I2C" under the folder named "libraries" in your Arduino sketchbook folder.
Create the folder "libraries" in case it does not exist yet. Place all the files in the "LiquidCrystal_I2C" folder.
# Usage #
To use the library in your own sketch, select it from *Sketch > Import Library*.
-------------------------------------------------------------------------------------------------------------------
This library is based on work done by DFROBOT (www.dfrobot.com).
File supplied by @swe-dude on the Arduino forum, and reported to be working with Maple mini

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@ -1,32 +0,0 @@
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
// Set the LCD address to 0x27 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27, 16, 2);
void setup()
{
// initialize the LCD
lcd.begin();
}
void loop()
{
bool blinking = true;
lcd.cursor();
while (1) {
if (blinking) {
lcd.clear();
lcd.print("No cursor blink");
lcd.noBlink();
blinking = false;
} else {
lcd.clear();
lcd.print("Cursor blink");
lcd.blink();
blinking = true;
}
delay(4000);
}
}

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@ -1,21 +1,20 @@
#include <Wire.h> #include <Wire.h>
#include <LiquidCrystal_I2C.h> #include <LiquidCrystal_I2C.h>
uint8_t bell[8] = {0x4, 0xe, 0xe, 0xe, 0x1f, 0x0, 0x4}; uint8_t bell[8] = {0x4,0xe,0xe,0xe,0x1f,0x0,0x4};
uint8_t note[8] = {0x2, 0x3, 0x2, 0xe, 0x1e, 0xc, 0x0}; uint8_t note[8] = {0x2,0x3,0x2,0xe,0x1e,0xc,0x0};
uint8_t clock[8] = {0x0, 0xe, 0x15, 0x17, 0x11, 0xe, 0x0}; uint8_t clock[8] = {0x0,0xe,0x15,0x17,0x11,0xe,0x0};
uint8_t heart[8] = {0x0, 0xa, 0x1f, 0x1f, 0xe, 0x4, 0x0}; uint8_t heart[8] = {0x0,0xa,0x1f,0x1f,0xe,0x4,0x0};
uint8_t duck[8] = {0x0, 0xc, 0x1d, 0xf, 0xf, 0x6, 0x0}; uint8_t duck[8] = {0x0,0xc,0x1d,0xf,0xf,0x6,0x0};
uint8_t check[8] = {0x0, 0x1 ,0x3, 0x16, 0x1c, 0x8, 0x0}; uint8_t check[8] = {0x0,0x1,0x3,0x16,0x1c,0x8,0x0};
uint8_t cross[8] = {0x0, 0x1b, 0xe, 0x4, 0xe, 0x1b, 0x0}; uint8_t cross[8] = {0x0,0x1b,0xe,0x4,0xe,0x1b,0x0};
uint8_t retarrow[8] = { 0x1, 0x1, 0x5, 0x9, 0x1f, 0x8, 0x4}; uint8_t retarrow[8] = { 0x1,0x1,0x5,0x9,0x1f,0x8,0x4};
// Set the LCD address to 0x27 for a 16 chars and 2 line display LiquidCrystal_I2C lcd(0x20,16,2); // set the LCD address to 0x20 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27, 16, 2);
void setup() void setup()
{ {
lcd.begin(); lcd.init(); // initialize the lcd
lcd.backlight(); lcd.backlight();
lcd.createChar(0, bell); lcd.createChar(0, bell);
@ -35,24 +34,21 @@ void setup()
lcd.print(" arduinos!"); lcd.print(" arduinos!");
delay(5000); delay(5000);
displayKeyCodes(); displayKeyCodes();
} }
// display all keycodes // display all keycodes
void displayKeyCodes(void) { void displayKeyCodes(void) {
uint8_t i = 0; uint8_t i = 0;
while (1) { while (1) {
lcd.clear(); lcd.clear();
lcd.print("Codes 0x"); lcd.print("Codes 0x"); lcd.print(i, HEX);
lcd.print(i, HEX); lcd.print("-0x"); lcd.print(i+16, HEX);
lcd.print("-0x");
lcd.print(i + 16, HEX);
lcd.setCursor(0, 1); lcd.setCursor(0, 1);
for (int j=0; j<16; j++) {
for (int j = 0; j < 16; j++) { lcd.write(i+j);
lcd.write(i + j);
} }
i += 16; i+=16;
delay(4000); delay(4000);
} }
@ -60,6 +56,5 @@ void displayKeyCodes(void) {
void loop() void loop()
{ {
// Do nothing here...
}
}

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@ -1,20 +1,17 @@
#include <Wire.h> #include <Wire.h>
#include <LiquidCrystal_I2C.h> #include <LiquidCrystal_I2C.h>
// Set the LCD address to 0x27 for a 16 chars and 2 line display LiquidCrystal_I2C lcd(0x20,16,2); // set the LCD address to 0x20 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27, 16, 2);
void setup() void setup()
{ {
// initialize the LCD lcd.init(); // initialize the lcd
lcd.begin();
// Turn on the blacklight and print a message. // Print a message to the LCD.
lcd.backlight(); lcd.backlight();
lcd.print("Hello, world!"); lcd.print("Hello, world!");
} }
void loop() void loop()
{ {
// Do nothing here...
} }

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@ -0,0 +1,24 @@
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd1(0x20,16,2); // set the LCD address of the first lcd to 0x20 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd2(0x21,16,2); // set the LCD address of the second lcd to 0x21 for a 16 chars and 2 line display
void setup()
{
lcd1.init(); // initialize the first lcd
lcd2.init(); // initialize the second lcd
// Print a message on the first LCD.
lcd1.backlight();
lcd1.print("Hello, #1 world!");
// Print a message on the second LCD.
lcd2.backlight();
lcd2.print("Hello, #2 world!");
}
void loop()
{
}

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@ -1,33 +1,30 @@
/** /*
* Displays text sent over the serial port (e.g. from the Serial Monitor) on * Displays text sent over the serial port (e.g. from the Serial Monitor) on
* an attached LCD. * an attached LCD.
*/ */
#include <Wire.h> #include <Wire.h>
#include <LiquidCrystal_I2C.h> #include <LiquidCrystal_I2C.h>
// Set the LCD address to 0x27 for a 16 chars and 2 line display LiquidCrystal_I2C lcd(0x20,16,2); // set the LCD address to 0x20 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27, 16, 2);
void setup() void setup()
{ {
lcd.begin(); lcd.init(); // initialize the lcd
lcd.backlight(); lcd.backlight();
// Initialize the serial port at a speed of 9600 baud
Serial.begin(9600); Serial.begin(9600);
} }
void loop() void loop()
{ {
// If characters arrived over the serial port... // when characters arrive over the serial port...
if (Serial.available()) { if (Serial.available()) {
// Wait a bit for the entire message to arrive // wait a bit for the entire message to arrive
delay(100); delay(100);
// Clear the screen // clear the screen
lcd.clear(); lcd.clear();
// read all the available characters
// Write all characters received with the serial port to the LCD.
while (Serial.available() > 0) { while (Serial.available() > 0) {
// display each character to the LCD
lcd.write(Serial.read()); lcd.write(Serial.read());
} }
} }

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@ -0,0 +1,55 @@
Notes for users with a Pollin.de interface board
http://www.pollin.de/shop/dt/NDU4OTgxOTk-/Bausaetze_Module/Bausaetze/LCD_I2C_Modul.html
The pollin interface board will not work with de default library.
To get it working two control lines to the LCD need to be changed.
Open file "LiquidCrystal_I2C.h" with a text editor like Notepad (not WordPad !)
In that file look for:
#define En B00010000 // Enable bit
#define Rw B00100000 // Read/Write bit
#define Rs B01000000 // Register select bit
Replace these lines by:
#define En B01000000 // Enable bit
#define Rw B00100000 // Read/Write bit
#define Rs B00010000 // Register select bit
People at Pollin also have misunderstood the PCF8574 Datasheet and list the wrong addresses on their PCB
For PCF8574A the addressing is:
Jp3 Jp2 Jp1
A2 A1 A0 Dec Hex
L L L 56 0x38
L L H 57 0x39
L H L 64 0x40
L H H 74 0x4A
H L L 75 0x4B
H L H 76 0x4C
H H L 77 0x4D
H H H 78 0x4E
They also seem to ship boards with a PCF8574
For PCF8574 the addressing is:
Jp3 Jp2 Jp1
A2 A1 A0 Dec Hex
L L L 32 0x20
L L H 33 0x21
L H L 34 0x22
L H H 35 0x23
H L L 36 0x24
H L H 37 0x25
H H L 38 0x26
H H H 39 0x27
They have also chosen two rather high pull-up resistors (10K) for the I2C lines. Usually two 4K7 resistors should do the job.
Please note that on a I2C bus only one device should have the pull-up resistors installed!
I hope this helps in getting your LCD working.
Mario

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@ -0,0 +1,36 @@
LiquidCrystal_I2C V2.0
The LiquidCrystal_I2C library is a modified version of the standard LiquidCrystal library as found on
the Arduino website.
This library is intended to be used when a parallel HD44780 compatible LCD is controlled over I2C using
a PCF8574 extender (see datasheet for details).
4 of the 8 outputs are used for LDC data lines 4 to 7.
3 outputs are used for the Enable, register-select and Read/Write lines.
The one output left can be used to control the backlight of the LCD (if available).
For backlight control some extra resistors and a pnp-type transistor are required (for details see
schematic diagram).
The PCF8574 extender is available in two versions, the PCF8574 and the PCF8574A.
The only difference between the two is the I2C base address.
The base address for the PCF8574 is 0x20 and the base address for the PCF8574A is 0x38.
The examples included in this zip file assume the use of an PCF8574 set for address 0x20
(A0, A1 and A3 grounded).
For compatibility reasons this library contains some aliases for functions that are known under different
names in other libraries. This should make it fairly easy to implement the library in existing sketches
without changing to much code.
Functions not supported by this library will return nothing at all and in case a return value is expected
the function will return 0.
Update 8-12-2011:
Due to the relaese of Arduino IDE 1.0 some changes were made to the library to get it working under the new IDE.
Because of these changes this version of the LiquidCrystal_I2C library can not be used for older IDE versions.
The old version of the LiquidCrystal_I2Clibrary can be downloaded form http://www.xs4all.nl/~hmario/arduino/LiquidCrystal_I2C/V1.0/LiquidCrystal_I2C_V1.0.zip
Download the latest version from:
http://www.xs4all.nl/~hmario/arduino/LiquidCrystal_I2C/LiquidCrystal_I2C.zip
(Thanks to Ailton F. for beta testing.)
Mario H.
atmega@xs4all.nl

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