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Topic: I^2C - 2004 - Backpack doesn*t seem to work  (Read 299 times) previous topic - next topic


I just bought an new I^2C liquid cristall display.
It has the dimensions 20 x 4 and a Blue backround.

The Controller is a pcf8574t.

Anyway, as I connected GND to Gnd VCC to 5V and the SDA and SCL to Pin 4 and 5 of my Leonardo
the Display began to light up.

The first and third row lighted up and the others stayed "dark". (Picture1)- seems normal to me

But after Hours of testing I Couldn't get any communication over the bus. No programm can access the adress , or initial the display .

Please help!


Surely a  Leonardo has TWI on PD0, PD1.

But you connect to the pins marked SDA, SCL.
You can be completely ignorant of which port pins are used.



Why did you decide to repost this same question another two times?
"Pete, it's a fool (who) looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.
I speak for myself, not Arduino.

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