The difference between the module I2C YW Robot LCM1602 IIC V1 and the module I2

What is the difference between the module I2C YW Robot LCM1602 IIC V1 and the module I2C LCM1602 IIC A0 A1 A2? I am not able to put the latter to work, then I observed that when the code was created for the first model YW Robot LCM1602 IIC V1, but does not work, nothing appears on the display.

Ok I am having a little difficulty understanding what it is you are saying.
I am familiar with the YwRobot display as I have one. I am not familiar with the other one you mentioned
can you please post a link to a vendor of this or to a photo ?
Second, when you say this:

I am not able to put the latter to work, then I observed that when the code was created for the first model YW Robot LCM1602 IIC V1, but does not work, nothing appears on the display.

what do you mean. Obviously something does not work but can you explain why you are comparing these two displays ?

I am not able to put the latter to work

This statement implies you ARE able to get the FORMER to work , right ?
So if you need help with "the latter is the any reason we need to talk about "the FORMER" ?
Please post a link to the display you need help with and post the code you are trying to use and specify the I2C library
you have installed and we can proceed , ok ?
If you need more information , please state what you need.

Reading just the first sentence of OP, i think i can answer his question (i have trouble following the rest too).

The difference between first and second board, is the I2C address.
First has a fixed address set to 0x27.
Second has it's address set to 0x20, but can be set to anything between 0x20 and 0x27, by removing or setting solder jumpers.
That module's type is not "I2C LCM1602 IIC A0 A1 A2".
A0, A1, A2 are the labels of those solder jumpers (Address 0, 1, 2), which happen to be placed directly next to the modules type name.

Fix the address to the module in your sketch and you'll be good to go.
Heck, you can even use both modules at the same time (up to 8 modules) if you like.

While it is possible that there is an address difference, that isn't the only potential issue.

There is no standard for how to wire up a PCF8574 chip to a hd44780 LCD interface and backlight circuit.
Therefore different vendors can wire them up differently on the PCBs.
So beyond having different I2C addresses, different backpacks can use different wiring.
It is possible that the two different backpacks you have use different wiring so they are not interchangeable
even when the proper address for each one is used.

You have not said which library you are using, but
I would recommend using fm's library.
It allows configuring the wiring so it can work with any backpack.
No other library allows this.
If your backpacks are wired differently, then you will need
to use fm's library unless you want to make custom library
for each board.

---- bill

"Who's on first ?" XD

Hi bperrybap.
You're absolutely right with your remark.
However i found this page (by just using Google) that shows this as the only difference i could find by just glimpsing over it.
These are the respective constructors shown:

lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);
lcd(0x20, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);

Both modules being from the same source, i assumed that in my previous post, but this seems to confirm it.

It is possible that they use the same wiring but with all the Chinese boards that copy
one another and simply slap a name/label on them, it’s hard to know for sure without actually testing them.
I’ve seen cases of multiple board layouts and wirings for boards that all have the
identical names/labels printed on them.
So the particular name/label on a board doesn’t guarantee a particular wiring.

— bill

Sorry to trouble writing in English, my language is Portuguese, I use google translate. To better explain my question:
I can not see anything on my 20x4 LCD display using I2C LCM1602 A0 A1 A2 IIC, can someone help me?

see Replies #2, 3, 5, & 6

Sorry to trouble writing in English, my language is Portuguese ...

You should have indicated this in your original post, perhaps by filling in the "location" information in your profile.

can someone help me?

Concentrate on translating reply #3.

We need to know more about the specific module that you are using since they frequently differ even if they look the same.

We also have to know the specific library that you are using since many have similar or identical names.

A photograph of both sides of your module might also help us help you.

Don

Unable to resolve using the code below, but I thank you for your attention. Includes picture of the module.

/* YourDuino.com Example Software Sketch
 20 character 4 line I2C Display
 ANOTHER NEW TYPE Marked "LCM1602 IIC  A0 A1 A2"
 A0-A1-A2 are grounded so I2C Address is 0x20  
 terry@yourduino.com */
/*-----( Import needed libraries )-----*/ 
#include <Wire.h>
#include <LCD.h>
#include <LiquidCrystal_I2C.h>  // F Malpartida's NewLiquidCrystal library
//Download: https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads
// Move original LiquidCrystal library elsewhere, copy this in it's place

/*-----( Declare Constants )-----*/
#define I2C_ADDR    0x20  // Define I2C Address for the PCF8574T 
//---(Following are the PCF8574 pin assignments to LCD connections )----
// This are different than earlier/different I2C LCD displays
#define BACKLIGHT_PIN  3
#define En_pin  2
#define Rw_pin  1
#define Rs_pin  0
#define D4_pin  4
#define D5_pin  5
#define D6_pin  6
#define D7_pin  7

#define  LED_OFF  1
#define  LED_ON  0

/*-----( Declare objects )-----*/  
LiquidCrystal_I2C  lcd(I2C_ADDR,En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);

void setup()   /*----( SETUP: RUNS ONCE )----*/
{
  lcd.begin (16,2);  // initialize the lcd 
// Switch on the backlight
  lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);
  lcd.setBacklight(LED_ON);
}// END Setup

void loop()   /*----( LOOP: RUNS OVER AND OVER AGAIN )----*/
{

// 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

That picture is from a website selling products.
Websites do not always show pictures of the exact same product they are selling.
Furthermore, that picture shows a backpack that has a PCF8574T, and solder jumpers.
It doesn't show the copper traces of the pcb, so we can't see what pin of that chip is connected to what pin of the LCD.

If you put a picture online, make one yourself of the product you actually have, and that does show as many traces as possible.

You need to run bperrybap's "i2cLCDguesser" which in excessive modesty, he did not cite! That will tell you which address and which descriptor is needed.

It's here.

Did you actually purchase your module from yourduino.com?

If you did then you should contact them (the address is right there in the code you posted) for assistance. Terry (terryking228) is a regular contributor to this forum and I am sure that he will help you get your LCD running.

Don

FYI, when you run the “Guesser”, READ THE INSTRUCTIONS at the beginning of the code .
BE SURE TO CHANGE YOUR SERIAL MONITOR LINE ENDING TO “NEWLINE”
HIT THE ENTER KEY TO START AND THE SERIAL MONITOR SEND BUTTON TO “GUESS”.
AFTER EACH GUESS, LOOK AT THE DISPLAY.
WHEN IT FINDS A MATCH, IT WILL PRINT THE CONSTRUCTOR (DESCRIPTOR,(whatever)) ON THE DISPLAY.
IT WILL LOOK something like this:

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

The one in your code looks like this:

 #define BACKLIGHT_PIN  3
#define En_pin  2
#define Rw_pin  1
#define Rs_pin  0
#define D4_pin  4
#define D5_pin  5
#define D6_pin  6
#define D7_pin  7

[b]LiquidCrystal_I2C  lcd(I2C_ADDR,En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);[/b]

WHEN it finds a match, write it down EXACTLY as it is displayed and replace the highlighted one in
yours with the one found in the match, (or plug the numbers into the #define statements for each pin)
Make sure you have THIS (same) library installed or the guesser won’t work.

 #include <LCD.h>
#include <LiquidCrystal_I2C.h>  // F Malpartida's NewLiquidCrystal library
//Download: https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads
// Move original LiquidCrystal library elsewhere, copy this in it's place