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Author Topic: [SOLVED] MJKDZ brand I2C Controller working with 1602 LCD  (Read 15828 times)
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Leicester UK
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Half intelligent old fart.....
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Hi All,
              I found my answer here with bperrybap's i2cLCDguesser sketch which after 8 guesses came up with the right answer to run my LCD with the small i2c backpack. You can follow the full thread here:;topicseen#new 

I also have another i2c backpack on it's way from China, so I may well have to do it all again, but at least this time I will know how to sort it, I hope!


f  you want, you can run my i2cLCDguesser sketch and it will walk through many of the
more common pin/wiring possibilities and you will see what the constructor parameters need
to be on the LCD display when the "guess" is finally correct.
Here is a link to the thread with the guesser sketch:

Just remember that this sketch uses fm's LiquidCrystal library.

Instructions for using the sketch are in the sketch itself.

--- bill

Open your mind, but not too far, your brain might fall out!!

Also like model building, photography and keeping an eye on my 294? Cacti & Succs...

Take a look at

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Hi, I'm here because my mjkdz behaves in a strange way  smiley-cry smiley-cry

with this sketch:
#include <Wire.h>
#include <LCD.h>
#include <LiquidCrystal_I2C.h>  // F Malpartida's NewLiquidCrystal library
/*-----( Declare Constants )-----*/
#define I2C_ADDR    0x27  // Direccion I2C para PCF8574A que es el que lleva nuestra placa diseñada por MJKDZ
//definimos las constantes para esta placa
#define  LED_OFF  0
#define  LED_ON  1
//mjkdz i2c LCD board
//                    addr, en,rw,rs,d4,d5,d6,d7,bl,blpol
LiquidCrystal_I2C lcd(I2C_ADDR, 4, 5, 6, 0, 1, 2, 3, 7, NEGATIVE);
void setup()  
  lcd.begin (16,2);  // inicializar lcd
// Activamos la retroiluminacion
void loop()


 // Reset the display  
  lcd.setBacklight(LED_OFF);//Backlight OFF
  lcd.backlight(); //Backlight ON
  lcd.print  ("hellohellohello!");

On my (16x2) LCD module; correctly connected to mjkdz... is displayed:" 1230123010123012" only in the first line and nothing in the second line  smiley-cry

with the same code; but the written :"hi how are you ?"
Appears strange symbols, Chinese or Japanese, I do not understand ... But that certainly are missing anything with the words that should appear... And nothing in the second line, another time...

Someone know the reason for these results? does anyone know a solution?

thank you very much for your attention, good day to all
« Last Edit: February 15, 2014, 11:17:35 am by Phanto » Logged

Dallas, TX USA
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This really has nothing to do with the original topic.
you really should start you own thread for this issue.
In the mean time, If I had to guess, I'd take a look at the solder connections.
Particularly the soldering on LCD pin 13.
We can all focus on your problem in your new thread.

It would be helpful if you could post a photo of your
backpack and the solder connections in your new thread.

--- bill

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I'm really sorry, I was hoping to find help, since there were keywords that related to my case. I am very sorry.

But, your guess is perfect! I cleaned the weld and the monitor started to work perfectly! You are a genius!  smiley

Thank you very much, thank you, thank you, thank you!
I apologize again and wish to all a good day!

thanks  smiley-kitty

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