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20 x 4 with backpack
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Please be positive and constructive with your questions and comments.
- tresguey
- Posts: 36
- Joined: Fri Oct 04, 2013 12:24 pm
20 x 4 with backpack
I have 2 of the 20 x 4 LCD displays with 2 backpacks. I connected everything up and ran the hello world program. The display blinks the back light and turns it off. It doesn't stay lit. I have tried both of them on 2 different Uno's.
- Franklin97355
- Posts: 23911
- Joined: Mon Apr 21, 2008 2:33 pm
Re: 20 x 4 with backpack
Have you modified the hello world code to turn off the blinking like the tutorial says?
You can read the whole thing HEREThe default HelloWorld sketch blinks the backlight as well as updating the text. If you see the backlight blinking that means your connection to the i2c port is OK but the contrast is too low or too high, or the LCD data pins are not solidly connected. Check the contrast first by gently twisting the mini trim potentiometer, if that doesn't help, recheck your soldering and resolder all 16 of the LCD pins!
Once you're done, you can remove the blinking LED backlight code:
lcd.setBacklight(HIGH);
delay(500);
lcd.setBacklight(LOW);
delay(500);
- tresguey
- Posts: 36
- Joined: Fri Oct 04, 2013 12:24 pm
Re: 20 x 4 with backpack
Didn't make much sense so I started testing my voltages. I found my new jumper wire I was using to supply ground to the backpack was defective. Works perfect now, should have checked them from the start. Oops.
Please be positive and constructive with your questions and comments.