20x4 ITC problems

Other Hardware Displays
1

//Have what looks like a chinese made ITC2 20x4 LCD module.
//Hooks up to my UNO3 connected to VCC GND and analog a4 and a5
//Here is my code compiled with the 1.2.1 Library and uploaded to the board

LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);
lcd.begin(20,4);
lcd.noBacklight(); //works fine
delay(750);
lcd.Backlight(); //works fine

// this dose not.. lcd remains lit and blank
lcd.setCursor(3,1); //Start at character 4 on line 1
lcd.print("Hello, world!");

//back of board shows a0 a1 a2 and not other labels
changing the first parameter of to 20 or 38 stops the baclight function form working, so I know that using the 0x27 is right.
//LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);

Would appreciate any help.

2

LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);

Are you sure that the pins called out in the constructor are correct? There is a LCD guesser program to help find the correct pinout for different LCDs. I'll try to find it.

edit:
[SOLVED] Using I2C 16x2 LCD with Arduino - Displays - Arduino Forum You can find to download the guesser form this post.

3

Thanks so much for answering.
I am an idiot, and realized that the contrast pot on the control board may have been in the wrong position. Once I turned it to the right, I started to see the text.
The ic2 test sketch reported..
"
Scanning i2c bus for devices..
i2c device found at address 0x27
Device found: PCF8574
"

Thanks again.

4

Glad it was that easy!