[Help] Conect LCD Display with PCF8574

Other Hardware Displays
1

Hi, i'm trying to connect a PCF8574 with a display and control it with arduino UNO.
i've read some tutorials but nothing is showing in the lcd only light up backlight... i'm using proteus to simulate...
i've downloaded LiquidCrystal_I2C.h library but its not helping...
that is a picture of the connections:

I'm Using the Hello World example:

#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(32,16,2);  // set the LCD address to 0x20 for a 16 chars and 2 line display

void setup()
{
  lcd.init();                      // initialize the lcd 
 
  // Print a message to the LCD.
  lcd.backlight();
  lcd.print("Hello, world!");
}

void loop()
{
}

anyone know what is happing? thanks

2

My virtual crystal ball says that you might try running a virtual I2C port scanner on your virtual I2C device.

What does your teacher say about this?

Don

3

your circuit is wrong!

The lines A0..A2 is to set the I2C address of the PCF8574 not the control lines for the RS/RW/EN pins of LCD

Also if your LCD follows the HD44780 standard, do the following:

  1. connect P0 to RS, P1 to E and set RW to GND (90% of cases you don't need read anything from LCD)
  2. connect P4 to D4;P5 to D5, P6, to D6, and P7 to D5
  3. set A0, A1, A2 to GND this will make the I2C slave address of PCF8574=0x20 (or if you are using PCF8574A=0x38)

Good luck!

4

IHi, i'm trying to connect a PCF8574 with a display and control it with arduino UNO.
i've read some tutorials but nothing is showing in the lcd only light up backlight... i'm using proteus to simulate...
that is a picture of the connections:
I'm Using the Hello World example:

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x20,16,2);
void setup()
{
lcd.init();
lcd.backlight();
lcd.print("Hello, world!");
}

void loop()
{
}

Sans titre.png
Sans titre.png1016×452 8.3 KB

5

Someone managed to simulate correctly with this example? For me it did not work.

6

licorini:
Someone managed to simulate correctly with this example? For me it did not work.

We don't simulate here.

If you get the wiring right, and the sketch right, it just works. If you get either wrong, simulation will not help you. :smiley:

7

make the I2C slave address of PCF8574=0x20
here is the working circuit

PCF8574.jpg

8

That can't work! It's too easy to follow. You don't have any extraneous zig-zags or crossed wires in your diagram.

Don

9

Use o PCF8574A
ligue da seguinte forma no LCD:

p0- RS
p2- E
p4- D4
p5- D5
p6- D6
p7- D7

SCL- A5 em pullup no arduino
SDA- A4 em pullup no arduino

A0, A1 e A2 do PCF8574A em high (VCC)

endereço 0x3f (LiquidCrystal_I2C lcd(0x3f, 16, 2))

10

You've waited nearly three years to give this advice. Surely you could have taken a few more minutes to run it through Google translate before posting it.

Use the PCF8574A
connect the following on the LCD:

p0- RS
p2- E
p4-D4
p5-D5
p6-D6
p7-D7

SCL-A5 in pullup on arduino
SDA-A4 in pullup on arduino

A0, A1 and A2 of PCF8574A in high (VCC)

address 0x3f (LiquidCrystal_I2C lcd (0x3f, 16, 2))

Don