VMA450 20x4 LCD not working with UNO R4 minima


I try to connect the VMA450 to an Arduino UNO R4 Minima, via I2C but I only get 2 empty lines and 2 full lines.
I used the example code of “Hello World”.
the library is loaded.
when I connect the screen to an older UNO it works fine.

Is there a compatibility issue with the uno R4 and I2C?

I read some posts on internet that there is a PULLUP resistor missing on the Arduino R4 boards. Is this causing my problem?

Thanks for helping me.

kind regards


Hi the Pull-up resistor are mounted on the VMA450.

You didn’t mix the SDA/SCL lines?
Have you tried with an I2C scanner sketch?
Does the UNO R4 detect the module?

I’m running into the same problem.

On arduino Uno R4 minima:

  • SDA / SCL lines connected to the SDA / SCL ports (or A4/A5).
  • when running a I2C scanner sketch, the lcd is not detected

When I try the exact same on arduino Uno:

  • SDA / SCL lines connected to the A4 / A5 ports.
  • when running a I2C scanner sketch, the lcd is detected on address 0x27

Problem is: I need the display on the arduino Uno R4.

Any suggestions?


Hello @SDM77

UNO R4 minima have no pull up resistors.

Try this library, normally it should work for VMA450 in combination with Arduino UNO R4 Minima.

Do not use the library from our site, it’s not working for Uno R4.

Best Regards,
Velleman Support


I used:

#include <LCD_I2C.h>
LCD_I2C lcd(0x27, 20, 4); // SDA=A4 ; SCL=A5

// for i2c variants, this must be called first.

lcd.setCursor(3, 0); //position 3 on first line.

lcd.print(“your text here”);

lcd.clear(); // clear the lcd screen

Hello Velleman support,

Thank you for the feedback! First of all I want to correct something:
The LCD I bought was in the shop advertised as VMa450, however I see now that it is actually the WPI450 LCD. (I don’t think this is a big difference as the velleman website links to the same files)

That said, I have been testing with the library you suggested, but no luck. I’m not getting a text on the screen, nor gets the lcd detected during an I2c scan. I tried 3 libraries in total. (every time removing the last one to prevent interference)

Finally I connected another LCD display (16x2) with the arduino r4 minima and I2c communication now works. I tried the 3 different libraries and the scanner, and all of them are able to communicate with the lcd display (16x2).

So It looks like there is a communication problem between the WPI450 LCD and Arduino uno R4, but not between the uno R4 and another I2c device.

Is there anything else I can try?

Hi Tom,
Thank you for the feedback, but I think there is some kind of a compatibility issue between The R4 and the display.


I work with an Arduino R4 minima.
My wires are connected on the digital side SCL/SCA (but they are linked to A4 and A5.

#include <Arduino.h>
#include <LCD_I2C.h>
LCD_I2C lcd(0x27, 20, 4); // SDA=A4 ; SCL=A5

void setup()


// Clears the LCD screen
// StartUpText
lcd.setCursor(0, 0);
lcd.setCursor(11, 0);
lcd.setCursor(0, 3);
lcd.print(“text on line 4:”);

I added a picture of the LCD I use.

Hello Tom,

Thank you for this information. Is it possible to tell me which LCD_I2c library you are using, or post a link to the files of this library please?

The setup and commands I have tried are the same as those you are using, so I figure the only difference can be in the used library.

Is it also possible to tell me what way you used to install this library?;Did you use the library manager to find the library, or did you download the files and placed the files in the library folder your self?

Many Thanks!