[SOLVED] LCD 1602A with PCF8574AT attached doesn´t work

Hi there,
I´ve got recently a shield LCD 1602A with PCF8574AT attached for my Arduino UNO and it doesn´t work.
I´ve tried with several sketchs for this shield and nothing happend.
The LCD issue and Arduino are completely new for me. I don´t know how a LCD works and his PCF8574AT attached. I should need some help to run the LCD 1602A with PCF8574AT attached. Also I should need some manual about how to manage these kind of LCD displays and Arduino (how to address the LCD, its memory and so on).



Read this.

Thanks, I´ll have a look and I´ll tell you later.

I´ve read the thread and follow the steps and nothing happened, just the same as ever (backlight on and the firsyt line of characters shows 16 doted rectangles).

I´ve connected GND, +5V, A4 to SDA, A5 to SCL.
I loaded the I2C scanner, to check if my I2C works well, and nothing happened.
If I disconnect A4 or A5 or both it happens the same (backlight on and the firsyt line of characters shows 16 doted rectangles).

Is so dificult to work with LCD displays and Arduino?

I´m lost and confussed. Idon´t know what to do or try to make it work.

I forgot to tell about my LCD display.The board of the LCD shows only 1602A and the I2C shows PCF8574AT (PHILIPS)

Thanks for any hints.

Sorry I forgot to attach two pictures to show my shield.

I loaded the I2C scanner, to check if my I2C works well, and nothing happened.

If the device is not recognized on the i2c bus, you can go no further. I don’t know what i2c scanner you used and what you mean by “nothing happened”. Use the scanner below, both with and without the device connected to A4/A5. Does it hang, or report “Found 0 devices”.

// I2C Scanner
// Written by Nick Gammon
// Date: 20th April 2011

#include <Wire.h>

void setup() {
  Serial.begin (115200);

  // Leonardo: wait for serial port to connect
  while (!Serial) 

  Serial.println ();
  Serial.println ("I2C scanner. Scanning ...");
  byte count = 0;
  for (byte i = 8; i < 120; i++)
    Wire.beginTransmission (i);
    if (Wire.endTransmission () == 0)
      Serial.print ("Found address: ");
      Serial.print (i, DEC);
      Serial.print (" (0x");
      Serial.print (i, HEX);
      Serial.println (")");
      delay (1);  // maybe unneeded?
      } // end of good response
  } // end of for loop
  Serial.println ("Done.");
  Serial.print ("Found ");
  Serial.print (count, DEC);
  Serial.println (" device(s).");
}  // end of setup

void loop() {}

You read that page, did you see and try the pull up resistors ? And did you try F.Malpartida's (fm) library ?

Thanks so muvh every body.

Now my LCD display with I2C is working.

Thanks cattledog to lead me to Nick Gammon,s scanner. Now I know the address of my I2C.

Now I want to know if the I2C may be used for other purposes. Tell me where can find information about that. And where can I learn more about LCD displays?

On the other han today I´ve another LCD display POWERTIP320240D and uses an SED1335F 0A. May I connect it to my ARDUINO UNO?

Thanks again.

I´ve got the solutions on that links hinted by MAS3 and cattledog



Both works.

What happened to me: i have a mega and try the scanner it said 0 device(s). so i've re checked wiring etc all was good, Thing that i've never noticed that the mega has a sda-scl ports(20-21) it tookme two days!

Many, many thanks for I2C address scanner. Thanks to this my devices are working.

I checked the I2C scanner and found the address to 0x3F. But after altering the address too I am not able to get anything display in my lcd except the backlight is turned on and prints 16 rectangle boxes on the first row