I2C LCD Serial Interface Board not displaying text (wrong pins?)

Question

I have a 1602 LCD screen that works fine on its own. However I wanted to free some pins by using an I2C / IIC LCD controller I purchased separately.

While the controller seems to be communicating with my Arduino UNO on the right address, I cannot get text to display. By default (no code) it seems the LCD will have 1 line of 16 solid "squares". When using address 27 in my code, the LCD will change to 2 lines of 16 squares (see photo below). The code also calls for the backlight to flash 3 times, which works. However I cannot get anything but 2 lines of squares. (Full code is at the bottom of this question).

I'm using the LiquidCrystal_I2C library by F Malpartida, which seems to be commonly used.
Is there a better library I should be using?

I'm wondering whether it's just the wrong pins being used in the code. All sketches I see online use the following pins:

//                    addr,en,rw,rs,d4,d5,d6,d7,bl,blpol
LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);
// Set the LCD I2C address

But all of the 1602 LCDs I see online have the same pins as mine, as you can see in my photo below:

These pins seem to be standard:

To further confuse me, the pins on the LCD board start with 1 on the left, yet the default code's pins seem to start with 0! So I tried changing the code's pins to the numbers on the LCD board. The LCD no longer changes to 2 lines of squares and no longer blinks the backlight. I then tried subtracting 1 from each pin (to start from 0), same result. I then tried used the default pins minus 1, same result. Thus the default pins are somehow more correct?! What am I doing wrong?

Has anyone else gotten one of these I2C controllers to work for them, and if so, how?

Full code:

/* YourDuino.com Example Software Sketch
 16 character 2 line I2C Display
 Backpack Interface labelled "YwRobot Arduino LCM1602 IIC V1"
 terry@yourduino.com */

/*-----( Import needed libraries )-----*/
#include <Wire.h>  // Comes with Arduino IDE
// Get the LCD I2C Library here: 
// https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads
#include <LiquidCrystal_I2C.h>

/*-----( Declare objects )-----*/
// set the LCD address to 0x27 for a 20 chars 2 line display
// Set the pins on the I2C chip used for LCD connections:
//                    addr, en,rw,rs,d4,d5,d6,d7,bl,blpol
LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);  // Set the LCD I2C address

void setup()   /*----( SETUP: RUNS ONCE )----*/
{
  Serial.begin(9600);  // Used to type in characters
  lcd.begin(16,2);   // initialize the lcd for 16 chars 2 lines, turn on backlight

// ------- Quick 3 blinks of backlight  -------------
  for(int i = 0; i< 3; i++) {
    lcd.backlight();
    delay(250);
    lcd.noBacklight();
    delay(250);
  }
  lcd.backlight(); // finish with backlight on  

//-------- Write characters on the display ------------------
// NOTE: Cursor Position: (CHAR, LINE) start at 0  
  lcd.setCursor(0,0); //Start at character 4 on line 0
  lcd.print("Hello, world!");
  delay(1000);
  lcd.setCursor(0,1);
  lcd.print("HI!YourDuino.com");
  delay(8000);  

// Wait and then tell user they can start the Serial Monitor and type in characters to
// Display. (Set Serial Monitor option to "No Line Ending")
  lcd.clear();
  lcd.setCursor(0,0); //Start at character 0 on line 0
  lcd.print("Use Serial Mon");
  lcd.setCursor(0,1);
  lcd.print("Type to display");  

}/*--(end setup )---*/

void loop()   /*----( LOOP: RUNS CONSTANTLY )----*/
{
  {
    // when characters arrive over the serial port...
    if (Serial.available()) {
      // wait a bit for the entire message to arrive
      delay(100);
      // clear the screen
      lcd.clear();
      // read all the available characters
      while (Serial.available() > 0) {
        // display each character to the LCD
        lcd.write(Serial.read());
      }
    }
  }

}/* --(end main loop )-- */

Answer 1

First of all, it looks like these wires aren't properly connected:

I haven't disassembled a female jumper before, so that might not be the issue. However, it seems likely that this could be a cause.

Also, you need to adjust the contrast by turning that trimmer (the blue thing that looks kinda like it has a screw in it). LCDs will either display nothing, a washed out version of the text, or blue boxes if the contrast is not set correctly. This is probably the cause.

Answer 2

I bought the SainSmart 20x04 and I also had to change the address to 0x3F. My backlight jumper was missing, that little header at the right of the I2C board provides the backlight power. Some code I found included this:

lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);

Answer 3

Change this code:

LiquidCrystal_I2C lcd(0x26, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);

To this:

LiquidCrystal_I2C lcd(0x26, 2, 1, 0, 4, 5, 6, 7, 8, POSITIVE);

(The argument before "POSITIVE" is changed from a 3 to an 8)