floresta:
Ok. Not initializing, that could also be wrong pins or pin order in the init command right?
Yes, those are some of the possible reasons.
Of course if you posted a photograph of your connections and a copy of your code we could help you guess.
Don
For now im using an example code..
/* YourDuino.com Example Software Sketch
20 character 4 line I2C Display
terry@yourduino.com */
/*-----( Import needed libraries )-----*/
#include <Wire.h>
#include <LCD.h>
#include <LiquidCrystal_I2C.h> // F Malpartida's NewLiquidCrystal library
/*-----( Declare Constants )-----*/
#define I2C_ADDR 0x20 // Define I2C Address for the PCF8574A
#define BACKLIGHT_PIN 7
#define En_pin 4
#define Rw_pin 5
#define Rs_pin 6
#define D4_pin 0
#define D5_pin 1
#define D6_pin 2
#define D7_pin 3
#define LED_OFF 0
#define LED_ON 1
/*-----( Declare objects )-----*/
LiquidCrystal_I2C lcd(I2C_ADDR,En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);
void setup()
{
lcd.begin (20,4); // initialize the lcd
lcd.setBacklightPin(BACKLIGHT_PIN,NEGATIVE);
lcd.setBacklight(LED_ON);
}
void loop()
{
// Reset the display
lcd.clear();
delay(1000);
lcd.home();
// Print our characters on the LCD
lcd.backlight(); //Backlight ON if under program control
lcd.setCursor(3,0); //Start at character 3 on line 0
lcd.print("Hello, world!");
delay(1000);
lcd.setCursor(2,1);
lcd.print("From YourDuino");
delay(1000);
lcd.setCursor(0,2);
lcd.print("20 by 4 Line Display");
lcd.setCursor(0,3);
delay(2000);
lcd.print("http://YourDuino.com");
delay(8000);
} // END Loop
This code turns the baklight on and of and displays (as stated before) only blobs on line 1 and 3. I have attached images of my setup.
The display i use comes with this information:
2004A LCD Screen J204A Character Display LCD Module 20x4 5v LCD / LCM (Blue)
Description:
Type: LCM2004A
Packaging: COB
Physical size: 98 mm x sixty mm
Connection mode: conductive rubber strip
Horizon size: 76 mm x 26 mm
Interface mode: single parallel
Dot size: 0.55 mm x 0.55 mm
Backlight type: EL/LED
Character size: 29.5 mm x 47.5 mm
Display content: twenty character x 4 line
Working voltage: + 5 V / + 3.3 V
Working temperature: -10°c~ +60°c
Controller: SPLC780
The chip on the "emall-4u I2C" says PCF8574T.
Not sure what else to give you..
Edit: Well, if i try to post images the page doesn't even want to try if i hit post. So i will explain my setup.
Arduino nano V3.0 (china-board)
SDA --> Analog 4
SCL --> Analog 5
Both with pullup to 5v