I2C communication problem

[Louis_Kortel]

Hello, I use a Controllino Maxi Automation board, with a 20×4 screen for displaying data. At first everything worked perfectly. Then I thought that my screen had cracked because impossible to use it even with an Arduino Uno card. So I ordered another I2C screen that I manage to use with an Arduino Uno board but not with my Controllino board. I have other I2C components like a RTC module and even a simple I2C scan doesn’t work.

The only diagnosis I can make is that the SDA (20) and SCL (21) pins of the Controllino board are connected to the ground, even when I try to use them…

Thank you for your help

[Johi]

Hello Luis_Kortel,

I have a Maxi-Power, i can measure the voltages on the SDA and SCL as a reference, would you like me to do this?

How did you power the backlight to the LCD, did you provide the power via the Controlino io of via a separate source?

Best Regards,

Johi.

[Louis_Kortel]

Hello Johi, thank you very much for your help.

Yes, I am happy to do so, thank you. Maybe that could help me!

I also have at my disposal a Uno board on which I can communicate in I2C with the screen or other I2C components. But with the Controllino Maxi Automation it is impossible for me to do this.

For power, I power the Controllino in 24V and it powers my screen via the 5V output pins.

To communicate I use SDA and SCL (20 and 21)

I was wondering if it was possible to flash my Controllino card with my Arduino Uno, I saw that this was possible for the Controllino Mini? Maybe that could tell me if my problem comes from hardware or software?

Best Regards,

Louis

[Johi]

Hello Louis_kortel,

In order to help you, i did the following:

I modified the I2C scanner and I downloaded it to my maxi-power.

Then i measured the voltage with my Fluke 117.

I saw varying voltages (around 3V) comming out of the pins SDA and SCL.

I would suggest you try the same and see if there is life on these pins.

If not i think your device might be broken.

#include <Wire.h>

void setup()

{

Serial.begin (9600);

} // end of setup

void loop()

{

Serial.println ();

Serial.println (“I2C scanner. Scanning …”);

byte count = 0;

Wire.begin();

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 (“)”);

count++;

delay (100); // maybe unneeded?

} // end of good response

} // end of for loop

Serial.println (“Done, restarting.”);

Serial.print (“Found “);

Serial.print (count, DEC);

Serial.println (” device(s).”);

}

Good Luck,

johi.

[Lukas]

Hello Louis,

just an idea – it happened to me some time ago that I have received another piece of I2C display (same type, same vendor) but the I2C address was different!

Lets use the I2C scanner to check it.

Best,

Lukas

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