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i2c LCD backpack - LCD not powering on
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i2c LCD backpack - LCD not powering on

by Arik80 on Thu Feb 14, 2019 1:43 pm

I'm using an assembled LCD (1447) and an i2c backpack (292). Board is Arduino Uno, DAT is connected to 4, CLK to 5. After soldering the backpack to the assembled lcd and powering up, nothing happens - no backlight at all. I've triple checked my soldering and don't see any issues. I also validated that the backpack is parallel to the lcd and isn't shorting out anywhere. Unfortunately I didn't test the LCD by itself before soldering the backpack on, so I can't tell if it's an LCD issue or a backpack issue....

i2c.JPG
i2c.JPG (129.14 KiB) Viewed 60 times

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Re: i2c LCD backpack - LCD not powering on

by adafruit_support_carter on Thu Feb 14, 2019 1:54 pm

Try running this I2C scanner sketch and see if it sees the backpack:
https://playground.arduino.cc/Main/I2cScanner

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Re: i2c LCD backpack - LCD not powering on

by Arik80 on Thu Feb 14, 2019 2:14 pm

Thanks for your help... The scanner shows I2C device found at address 0x20

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Re: i2c LCD backpack - LCD not powering on

by adafruit_support_carter on Thu Feb 14, 2019 2:21 pm

OK, so it's being seen at least. Try adjusting the constrast knob - the little trim pot on the backpack. Are you running this demo?
https://learn.adafruit.com/i2c-spi-lcd- ... d-demo-4-7

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Re: i2c LCD backpack - LCD not powering on

by Arik80 on Thu Feb 14, 2019 2:22 pm

Ugh.... Just realized that I made the i2c connections on the Arduino to pins 4 and 5, rather than A4 and A5.... Swapped them and it fired right up. Derp. Thanks for your help!!!

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Re: i2c LCD backpack - LCD not powering on

by adafruit_support_carter on Thu Feb 14, 2019 2:29 pm

Good catch! I totally missed that also.

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