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Topic: I2C scanner. Scanning ... Done. Found 0 device(s).? (Read 140 times) previous topic - next topic


I  have an lcd 20x4 connected to a  Due but getting the following scanner output:

I2C scanner. Scanning ...
Found 0 device(s).

I have tried it both on 5v and 3.3v with same results.


I'm trying to connect an LCD 20x4 to a Due but other than getting the back light nothing else is happening. Using the scanner shows :
No I2C devices found

Should the Due 5v be connected to the LCD or the 3.3?

I'm using these pins:
LiquidCrystal_I2C lcd(23, 25, 27, 29, 31, 33);


I guess if you connect your display via I2C, you should use SDA/SCL/GND (pull ups included in the DUE side) or SDA1/SCL1/GND(pull ups not included in the DUE side).

Regarding the power supply of your LCD (although not the same) in I2C mode, this thread should help :



Thanks for pointing me to the right direction for now. For newbies like myself I found the below info which can help understand the basics better:

 On the Arduino boards with the R3 layout (1.0 pinout), the SDA (data line) and SCL (clock line) are on the pin headers close to the AREF pin. The Arduino Due has two I2C / TWI interfaces SDA1 and SCL1 are near to the AREF pin and the additional one is on pins 20 and 21.
As a reference the table below shows where TWI pins are located on various Arduino boards.

Board   I2C / TWI pins
Uno, Ethernet   A4 (SDA), A5 (SCL)
Mega2560   20 (SDA), 21 (SCL)
Leonardo   2 (SDA), 3 (SCL)
Due   20 (SDA), 21 (SCL), SDA1, SCL1


Well I just learnt I2C LCD Interface allows you to connect an LCD to a micro controller with only two wires and a back pack that mounts on the LCD is needed butI rather need to connect the LCD directly and so far I have discovered it does not work off of the 3.3v but it's OK with the 5v directly off of the Due if V0 gets connected directly to the ground via a 1k resistor!
Is this procedure OK and it wouldn't damage the Due?


Is this procedure OK and it wouldn't damage the Due?

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