Each new circuit I build, I seem to make every possible mistake, including inverting 5V and ground. I did that precise mistake on this 2x16 Sainsmart LCD. The backlight definitely works, but is the only thing I seem to be able to make work. Do you believe I fried the screen, or do they maybe have a diode to protect from erroneous cabling, and my mistake is another one?


I found this somewhere, on a board that might be the one driving this LCD screen or not :

Operating Voltage VDD -0.3 to +7.0 V Driver Supply Voltage VLCD VDD - 10 to VDD + 0.3

So I mistakenly put 5V in VLCD, and 0V in VDD, which makes VLCD 5V and not 0.3V above VDD, would you suppose I fried it?

Thanks for your input :)

  • Make sure you set the contrast using a potentiometer. Not seeing anything on the display, doesn't mean it's not working. If you only connect Vcc, GND and the Contrast pin, and you turned the pot to the correct position, you should see the first line filled with solid block, and the second line should be clear.
    – Gerben
    Apr 7, 2016 at 18:42
  • These things are reslient, because, according to the datasheet I was 4.7V outside specs, and your trick did it. I suppose if I saw the matrix of dots, it means it can print dots, and if it can print dots, it ain't fried. Thanks. Now I'll have five extras, but that'll just mean five projects who could do without will do with a LCD :D
    – pouzzler
    Apr 7, 2016 at 19:19
  • 1
    I just succesfully did the hello world, thanks to you. If you'd only make an answer rather than a comment, I'd be able to select it. In any which case, thank you.
    – pouzzler
    Apr 7, 2016 at 19:35

1 Answer 1


For me, it's extremely hard to tell if you did or did not fry a device. Even if you have the device right in front of you, it's often hard to tell.

You've got two options:

Attempt to diagnose it

First you should try to run example code and follow the "instructions". I believe this product is relatively well documented (/libraried?) and shouldn't be all too hard to set up.

If this isn't working, it's likely the device is dead (given the situation). You could go on and fiddle around with it for hours, which might not be worth the effort.

Buy a new one

This will cost you some money. But if you get the new one working, you can test the same code on your old one.


  1. First connect the wires, check the wiring and AFTER THAT connect the power. (Especially take care on GND/VCC wiring.)
  2. Use black wires for GND/ground and red wires for VCC/5V.(It'll be easier to manage/spot)
  3. Check the devices datasheets (which pins, what maximal voltage)
  4. Try to use female connectors as power-output. (They don't short everything they touch)
  5. Try to use irreversible connectors.
  6. Don't have loose leads dangling around.
  7. Put a casing/backplate on your Arduino (and/or avoid placing it on metal)
  8. Keep your desk clean, bits of solder, wire, leads or screws may cause shorts between pins.
  • It may also be worth checking if only the "LCD driver" isn't working.
    – aaa
    Apr 7, 2016 at 11:09
  • I ordered some LCDs (5 for 7 euros, crazy); they will probably take some time to come here, I'll answer when they do and I test a hello world on them.
    – pouzzler
    Apr 7, 2016 at 14:11
  • Neat! Do they come with an "LCD driver"? Or well, it would be possible to drive them directly, but that would take a little more pins.
    – aaa
    Apr 8, 2016 at 17:17
  • No, no driver, six pins (if you only write, seven if you read)
    – pouzzler
    Apr 20, 2016 at 10:23

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