LCD I2C library doesn't work with Leonardo and ProMicro boards

userHead Account cancelled 2014-04-06 16:11:33 3600 Views1 Replies
Hi. I have a problem with LiquidCrystal_I2C library and 32U4-based Arduino boards.

I tried "Hello World" example with Uno, it works flawlessly with 2 different LCD screens.

Before trying LCD code I verified I2C address using well-known "I2C scanner" sketch, it outputs

I2C device found at address 0x77  !

exactly as it should.

Then I connect my LCD to Sparkfun ProMicro 5V 16Mhz (keeping in mind that it uses D2 and D3 instead of A4 and A5 pins for I2C) and check I2C address of the screen again. I get the same output which means wiring is correct.

Then I upload the "Hello World" sketch supplied with the library again and I get nothing. Even backlight doesn't work.

It is clearly an compatibility issue between Uno and Leonardo. I have seen similar reports (for example, ... h-leonardo) - so I assume it is not only mine problem.

Any ideas how to fix this?
2014-04-08 18:06:08 Hello Sanja
Sorry for the late reply.
Which LCD are you using now?
Yeah, Leonardo are using D2&D3 to instead of A4&A5.
You said the backlight doesn't work? Generally, when your LCD module is power on, the backlight will be turned on. I tried the Leonardo IIC communication before. it is right.
What is your ProMicro power supply? Could you take a photo with the hardware connection?
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