16x4 LCD w/ backpack - lcd.setcursor strange behaviour

Hi folks

I´ve noticed a strange behaviour using 16x4 LCD and I2C library and the lcd.setcursor command.
When using lcd.setcusor(0,3) all that is written in the LCD is done in line 2, instead the line 4..
Accidentally I discovered if using lcd.setcursor(16,1) the data is written in line 4 perfectly.
Why? And what can be done to correct it? Did someone faced this situation?

Erratic code:

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x20,16,2); 

void setup() {
              lcd.init();   
              lcd.backlight();
              }

void loop () {
lcd.setcursor(0,0); lcd.print("1111111111111111");
lcd.setcursor(0,1); lcd.print("2222222222222222");
lcd.setcursor(0,2); lcd.print("3333333333333333");
lcd.setcursor(0,3); lcd.print("4444444444444444");
}

Workaround / Compensated code:

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x20,16,2); 

void setup() {
              lcd.init();   
              lcd.backlight();
              }

void loop () {
lcd.setcursor(0,0); lcd.print("1111111111111111");
lcd.setcursor(0,1); lcd.print("2222222222222222");
lcd.setcursor(0,2); lcd.print("3333333333333333");
lcd.setcursor(16,1); lcd.print("4444444444444444");
}

Why? And what can be done to correct it? Did someone faced this situation?

The Lib works perfect with 4x20, dont know why it shouldnt @ 16x4...

Its very curious that the lib "knows" 3 rows, but bot the forth :fearful:

Did you check the depending part in the lib ?

Hi, thank you....

the depending part you mean the "cpp" file?
I dont know yet how to handle it correctly. The only change I´ve made was that regarding fisrt char address that the fellows here http://forum.arduino.cc/index.php/topic,14604.0.html instructed to change due to column error.

Below is the CPP

// LiquidCrystal_I2C V2.0

#include "LiquidCrystal_I2C.h"
#include <inttypes.h>
#include "Wire.h"
#include "Arduino.h"

// When the display powers up, it is configured as follows:
//
// 1. Display clear
// 2. Function set:
// DL = 1; 8-bit interface data
// N = 0; 1-line display
// F = 0; 5x8 dot character font
// 3. Display on/off control:
// D = 0; Display off
// C = 0; Cursor off
// B = 0; Blinking off
// 4. Entry mode set:
// I/D = 1; Increment by 1
// S = 0; No shift
//
// Note, however, that resetting the Arduino doesn't reset the LCD, so we
// can't assume that its in that state when a sketch starts (and the
// LiquidCrystal constructor is called).

LiquidCrystal_I2C::LiquidCrystal_I2C(uint8_t lcd_Addr,uint8_t lcd_cols,uint8_t lcd_rows)
{
_Addr = lcd_Addr;
_cols = lcd_cols;
_rows = lcd_rows;
_backlightval = LCD_NOBACKLIGHT;
}

void LiquidCrystal_I2C::init(){
init_priv();
}

void LiquidCrystal_I2C::init_priv()
{
Wire.begin();
_displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;
begin(_cols, _rows);
}

void LiquidCrystal_I2C::begin(uint8_t cols, uint8_t lines, uint8_t dotsize) {
if (lines > 1) {
_displayfunction |= LCD_2LINE;
}
_numlines = lines;

// for some 1 line displays you can select a 10 pixel high font
if ((dotsize != 0) && (lines == 1)) {
_displayfunction |= LCD_5x10DOTS;
}

// SEE PAGE 45/46 FOR INITIALIZATION SPECIFICATION!
// 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
delayMicroseconds(50000);

// Now we pull both RS and R/W low to begin commands
expanderWrite(_backlightval); // reset expanderand turn backlight off (Bit 8 =1)
delay(1000);

//put the LCD into 4 bit mode
// this is according to the hitachi HD44780 datasheet
// figure 24, pg 46

// we start in 8bit mode, try to set 4 bit mode
write4bits(0x03);
delayMicroseconds(4500); // wait min 4.1ms

// second try
write4bits(0x03);
delayMicroseconds(4500); // wait min 4.1ms

// third go!
write4bits(0x03);
delayMicroseconds(150);

// finally, set to 4-bit interface
write4bits(0x02);

// set # lines, font size, etc.
command(LCD_FUNCTIONSET | _displayfunction);

// turn the display on with no cursor or blinking default
_displaycontrol = LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF;
display();

// clear it off
clear();

// Initialize to default text direction (for roman languages)
_displaymode = LCD_ENTRYLEFT | LCD_ENTRYSHIFTDECREMENT;

// set the entry mode
command(LCD_ENTRYMODESET | _displaymode);

home();

}

/********** high level commands, for the user! */
void LiquidCrystal_I2C::clear(){
command(LCD_CLEARDISPLAY);// clear display, set cursor position to zero
delayMicroseconds(2000); // this command takes a long time!
}

void LiquidCrystal_I2C::home(){
command(LCD_RETURNHOME); // set cursor position to zero
delayMicroseconds(2000); // this command takes a long time!
}

void LiquidCrystal_I2C::setCursor(uint8_t col, uint8_t row){
int row_offsets[] = { 0x00, 0x40, 0x10, 0x50 };
if ( row > _numlines ) {
row = _numlines-1; // we count rows starting w/0
}
command(LCD_SETDDRAMADDR | (col + row_offsets[row]));
}

// Turn the display on/off (quickly)
void LiquidCrystal_I2C::noDisplay() {
_displaycontrol &= ~LCD_DISPLAYON;
command(LCD_DISPLAYCONTROL | _displaycontrol);
}
void LiquidCrystal_I2C::display() {
_displaycontrol |= LCD_DISPLAYON;
command(LCD_DISPLAYCONTROL | _displaycontrol);
}

// Turns the underline cursor on/off
void LiquidCrystal_I2C::noCursor() {
_displaycontrol &= ~LCD_CURSORON;
command(LCD_DISPLAYCONTROL | _displaycontrol);
}
void LiquidCrystal_I2C::cursor() {
_displaycontrol |= LCD_CURSORON;
command(LCD_DISPLAYCONTROL | _displaycontrol);
}

// Turn on and off the blinking cursor
void LiquidCrystal_I2C::noBlink() {
_displaycontrol &= ~LCD_BLINKON;
command(LCD_DISPLAYCONTROL | _displaycontrol);
}
void LiquidCrystal_I2C::blink() {
_displaycontrol |= LCD_BLINKON;
command(LCD_DISPLAYCONTROL | _displaycontrol);
}

// These commands scroll the display without changing the RAM
void LiquidCrystal_I2C::scrollDisplayLeft(void) {
command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVELEFT);
}
void LiquidCrystal_I2C::scrollDisplayRight(void) {
command(LCD_CURSORSHIFT | LCD_DISPLAYMOVE | LCD_MOVERIGHT);
}

// This is for text that flows Left to Right
void LiquidCrystal_I2C::leftToRight(void) {
_displaymode |= LCD_ENTRYLEFT;
command(LCD_ENTRYMODESET | _displaymode);
}

// This is for text that flows Right to Left
void LiquidCrystal_I2C::rightToLeft(void) {
_displaymode &= ~LCD_ENTRYLEFT;
command(LCD_ENTRYMODESET | _displaymode);
}

// This will 'right justify' text from the cursor
void LiquidCrystal_I2C::autoscroll(void) {
_displaymode |= LCD_ENTRYSHIFTINCREMENT;
command(LCD_ENTRYMODESET | _displaymode);
}

// This will 'left justify' text from the cursor
void LiquidCrystal_I2C::noAutoscroll(void) {
_displaymode &= ~LCD_ENTRYSHIFTINCREMENT;
command(LCD_ENTRYMODESET | _displaymode);
}

// Allows us to fill the first 8 CGRAM locations
// with custom characters
void LiquidCrystal_I2C::createChar(uint8_t location, uint8_t charmap[]) {
location &= 0x7; // we only have 8 locations 0-7
command(LCD_SETCGRAMADDR | (location << 3));
for (int i=0; i<8; i++) {
write(charmap*);*

  • }*
    }
    // Turn the (optional) backlight off/on
    void LiquidCrystal_I2C::noBacklight(void) {

  • _backlightval=LCD_NOBACKLIGHT;*

  • expanderWrite(0);*
    }
    void LiquidCrystal_I2C::backlight(void) {

  • _backlightval=LCD_BACKLIGHT;*

  • expanderWrite(0);*
    }
    /*********** mid level commands, for sending data/cmds */
    inline void LiquidCrystal_I2C::command(uint8_t value) {

  • send(value, 0);*
    }
    inline size_t LiquidCrystal_I2C::write(uint8_t value) {

  • send(value, Rs);*

  • return 0;*
    }
    /************ low level data pushing commands **********/
    // write either command or data
    void LiquidCrystal_I2C::send(uint8_t value, uint8_t mode) {

  • uint8_t highnib=value>>4;*

  • uint8_t lownib=value & 0x0F;*

  • write4bits((highnib)|mode);*

  • write4bits((lownib)|mode);*
    }
    void LiquidCrystal_I2C::write4bits(uint8_t value) {

  • expanderWrite(value);*

  • pulseEnable(value);*
    }
    *void LiquidCrystal_I2C::expanderWrite(uint8_t _data){ *

  • Wire.beginTransmission(_Addr);*

  • Wire.write((int)(_data) | _backlightval);*

  • Wire.endTransmission(); *
    }
    void LiquidCrystal_I2C::pulseEnable(uint8_t _data){

  • expanderWrite(_data | En); // En high*

  • delayMicroseconds(1); // enable pulse must be >450ns*

  • expanderWrite(_data & ~En); // En low*

  • 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){

  • createChar(char_num, rows);*
    }
    void LiquidCrystal_I2C::setBacklight(uint8_t new_val){

  • if(new_val){*

  • backlight(); // turn backlight on*

  • }else{*

  • noBacklight(); // turn backlight off*

  • }*
    }
    void LiquidCrystal_I2C::printstr(const char c[]){

  • //This function is not identical to the function used for "real" I2C displays*

  • //it's here so the user sketch doesn't have to be changed*

  • 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){}

[/quote]

the depending part you mean the "cpp" file?

Yes

The only change I´ve made was that regarding fisrt char address that the fellows here http://forum.arduino.cc/index.php/topic,14604.0.html instructed to change due to column error.

Aha, and before that changing there where the same results ?

Good point. I will made a roll back in the cpp file and test again.
I might had screwed something, in fact.
After that will post the results here.....

The Lib works perfect with 4x20, dont know why it shouldnt @ 16x4...

If the library in question is based on or if it uses the 'official' LiquidCrystal library then it will not work correctly with the 16x4 simply because the LiquidCrystal library itself does not work correctly with 16x4 displays.

This is due to the fact that the initial address for rows 3 and 4 are different for the two displays and the LiquidCrystal library does not account for this fact.

This is a known problem that has come up several times in the past five years, here are some examples:
http://forum.arduino.cc/index.php?topic=14604.0
http://forum.arduino.cc/index.php?topic=46666.0
http://forum.arduino.cc/index.php?topic=63038.0
http://forum.arduino.cc/index.php?topic=70011.0
http://forum.arduino.cc/index.php?topic=93976.0
http://forum.arduino.cc/index.php?topic=190544.msg1408694#msg1408694

And here is the solution:
http://forum.arduino.cc/index.php?topic=63038.15

For background information follow the LCD Addressing link at http://web.alfredstate.edu/weimandn

Don

And here is the solution:
[solved] 16x4 LCD: Characters in row 3&4 are moved to the right - Displays - Arduino Forum

Thx for the link - i found also 3 of those lcds in my waste-box and can now use them

Another example of why I prefer fm's LiquidCrystal library.
It has been updated for the proper cursor addressing.

--- bill

Another example of why I prefer fm's LiquidCrystal library

which can be found here:
https://bitbucket.org/fmalpartida/new-liquidcrystal/wiki/Home

Hi All,
As I understand it 4 line LCD's have the line addresses as follows 1-3-2-4. In another life with Picaxe uCs it went something like line-1 128, line-2 192, line-3 148 and line-4 212, but in Picaxe that's just what we put in the basic code. How arduino does it I don't know but I should, as I have a couple of 20x4 displays!!

Hope it helps.
Regards
Mel.

As I understand it 4 line LCD's have the line addresses as follows 1-3-2-4.

Thats correct, because the length of a row (HD44780 lcds) is 40 chars on a 4x20 display.
if the cursorposition reaches i.e. 21, the controller switches that internally to lcd row 2.

As I understand it 4 line LCD's have the line addresses as follows 1-3-2-4.

... the controller switches that internally to lcd row 2.

Neither of these is a correct interpretation of what is actually happening. You cannot simplify the operation down to a sentence or two because of the basic underlying fact that there is no way for the LCD controller to determine the configuration of the attached display.

The controller can be informed of how many lines of memory to use, but this is not the same as how many rows of characters there are on the display. You must be very careful in the distinction between terms line and row or you will become hopelessly confused and will perpetuate this confusion by posting inaccurate information.

The displays with four rows of characters on the display use two lines of memory in the controller. If you just spit out characters to the display they will fill the display in the order mentioned above, rows 1-3-2-4. The addresses associated with the beginning of two of the rows are different for 16x4 and 20x4 displays.

There is a gap in the addresses between the end of line 1 in memory and the beginning of line 2 in memory. The controller automatically accounts for this gap so that if you just spit out characters to the display none are sent to those non existant addresses.

You really have to read the description I linked to at the end of reply #5 to completely understand the relationship between the controller memory addresses and the location of the characters on the display.

Don

Neither of these is a correct interpretation of what is actually happening. You cannot simplify the operation...

I know that,too - but won't make him more confuse about this and described it simple

I know that,too - but won't make him more confuse about this and described it simple.

'Simple' isn't good enough if it is also incorrect.

Don