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I've used my LCD display with a lot of small projects. Now it doesn't work anymore. Most of the diagrams you find online use resistors and potentiometers. However I never done that, but still got it to work nonetheless.

I tried different schematics, but none of them seem to work. So I'm thinking I broke my LCD somehow.

I'm pretty sure the schematic I'm currently using works. The backlight works but nothing is being printed.

Pictures of the project (Warning!! wire hell)

The LCD component is a blue 16x2 1602A v2.0 display. All the components come from the official Arduino starter kit, except for the wires. Though I tested every single wire for continuity, to make absolutely sure the problem was not within the wires themselves. Also, turning the potentiometer doesn't show any blocks, or change anything on the LCD as expected.

Code:

#include <LiquidCrystal.h>
//LiquidCrystal lcd(RS, E, D4, D5, D6, D7);
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  pinMode(6,OUTPUT);
  analogWrite(6,90); //sweetspot for backlight without using a potentiometer.

  lcd.begin(16, 2);
  //lcd.setCursor(0,0);
  lcd.print("hello, world!");
}

void loop() {
}

I'm not sure what's wrong, I tested everything I can think off.

I can upload more (cleaner) pictures if requested, I just didn't want to tear down my other project.

  • Contrast? Adjust the contrast pot until something (even a black box) is displayed. – user31481 Dec 18 '17 at 23:42
  • What do you mean? I said that turning the potentiometer doesn't change anything to the display. – Edward Dec 19 '17 at 0:11
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    Two things: bright and contrast. You are controlling bright. For contrast, the old LCD that comes with the Start Kit (mine, at least), use pin 3 (V0) to control contrast. You can add a pot there. Newer I2C versions comes a pot to the same effect. – user31481 Dec 19 '17 at 8:03
  • Look at the schematic I posted, this is exactly what I'm doing, the potentiometer is connected to the 3rd pin on the display (V0). The brightness is being controlled by PWM on pin 6, value 90 gives it just enough backlight for things to be readable. I've always used it like this. – Edward Dec 19 '17 at 12:09
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    You posted not a schematic but a drawing of you circuit. A schematic show clearly how things are connected (pin number/name). A schematic doesn't include a graphic representation of the parts involved; all of them are represented by symbols. Goal is to communicate information in a precise, complete and concise way. – user31481 Dec 19 '17 at 15:29
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Ok so the problem were the wires. Although I tested every single wire for continuity I went to the store and bought a brand new (expensive/not-from-aliexpress) pack of jumper wires. I rewired the entire project with the schematic and code that was posted in my question-post and it worked like a charm..

So I'm not sure what exactly caused the problem, but it was in the wire. I thought having continuity in a wire is like a 100% proof that the wire works properly. Maybe someone has an idea what could cause this?

So again, I only replaced the wires, not the schematic nor the code, with brand new ones and it worked perfectly.

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I have an suggestion. Try removing the comment from this line: //lcd.setCursor(0,0);

You need to be sure your text is displaying on the first line, first position(0,0).

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The LCD is working perfectly fine (hardware side).

Only 2 changes require in your code.

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  pinMode(6,OUTPUT);
  analogWrite(6,90); //sweetspot for backlight without using a potentiometer.

  lcd.begin(16, 2);
  lcd.setCursor(0,0);
  lcd.print("hello, world!");
  delay(3000);
}

void loop() {
}

Added delay (it must!) and set the cursor position.

Try above code and let inform.

  • Adding delay or change the cursor position did not change anything. I don't even think it is necessary. Cursor position is by default on (0,0). – Edward Dec 19 '17 at 14:41
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(This is a duplicate).

I solved it following this:

The contrast can be adjusted by the potential-meter displayed in the following picture.

enter image description here

credit

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