# My arduino uno r3 isnt running the example code liquidcrystal blink

**URL:** <https://forum.arduino.cc/t/my-arduino-uno-r3-isnt-running-the-example-code-liquidcrystal-blink/1456104>\
**Category:** Displays\
**Created:** [August 16, 2026, 8:43pm UTC](https://forum.arduino.cc/t/my-arduino-uno-r3-isnt-running-the-example-code-liquidcrystal-blink/1456104 "2026-08-16T20:43:07Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![hamman1234](https://avatars.discourse-cdn.com/v4/letter/h/3bc359/32.png) [@hamman1234](https://forum.arduino.cc/u/hamman1234)\
**Post date:** [August 16, 2026, 8:43pm UTC](https://forum.arduino.cc/t/my-arduino-uno-r3-isnt-running-the-example-code-liquidcrystal-blink/1456104/1 "2026-08-16T20:43:07Z")

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for some reason it will run regular blink but not the lcd version even though its uploads both of them fine and the lcd works and is on. the lcd is wired correctly and i triple checked everything and use 2 diffrents board but it still wont work, can i have some help 🙏

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**Author:** ![UKHeliBob](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ukhelibob/32/215663_2.png) [@UKHeliBob](https://forum.arduino.cc/u/UKHeliBob)\
**Post date:** [August 16, 2026, 8:58pm UTC](https://forum.arduino.cc/t/my-arduino-uno-r3-isnt-running-the-example-code-liquidcrystal-blink/1456104/2 "2026-08-16T20:58:17Z")

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Welcome to the forum

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**Author:** ![xfpd](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/xfpd/32/1120236_2.png) [@xfpd](https://forum.arduino.cc/u/xfpd)\
**Post date:** [August 17, 2026, 1:12am UTC](https://forum.arduino.cc/t/my-arduino-uno-r3-isnt-running-the-example-code-liquidcrystal-blink/1456104/3 "2026-08-17T01:12:20Z")

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> [@hamman1234](#):
>
> lcd version

There are TWO types of LCD wiring. (1) IIC/I2C and (2) Parallel.

The "parallel" version of an "LCD blink" sketch will only work if you "modulate" the Anode pin of the LCD.

The wiring for parallel (with relay for Anode modulation):

 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/e/c/f/ecf4343dce4b2044ce2aef5611c26af9ddd7894f.png)

The sketch for parallel (note: library):

```arduino
#include <LiquidCrystal.h> // library
byte rs = 12, en = 10, d4 = 5, d5 = 4, d6 = 3, d7 = 2; // pins for the LCD
LiquidCrystal lcd(rs, en, d4, d5, d6, d7); // configure LCD instance
unsigned long timer, timeout = 1000; // timing
byte relayPin = 13; // pin to control relay

void setup() {
  pinMode(relayPin, OUTPUT); // configure relay pin
  digitalWrite(relayPin, HIGH);
  lcd.begin(16, 2); // start LCD
  lcd.setCursor(5, 0); // cursor on first row, seventh column
  lcd.print("Hello,"); // print message on LCD
  lcd.setCursor(5, 1); // cursor on second row, seventh column
  lcd.print("World!"); // print message on LCD
}

void loop() {
  if (millis() - timer >= timeout) { // wait for timeout
    timer = millis(); // reset timer
    digitalWrite(relayPin, !digitalRead(relayPin));
  }
}

```

The I2C/IIC version of "LCD blink" has a means of cycling the backlight on and off, like this:

The wiring for I2C:

 ![image](https://europe1.discourse-cdn.com/arduino/original/4X/e/e/0/ee0ced641b107d956a993c06c9c7301ee6170166.png)

The sketch for I2C: (note the library)

```arduino
#include <LiquidCrystal_I2C.h> // library
#define ADDR 0x27 // LCD address
#define COLS 16 // LCD columns
#define ROWS 2 // LCD rows
LiquidCrystal_I2C lcd(ADDR, COLS, ROWS); // configure LCD instance
unsigned long timer, timeout = 1000; // timing
bool toggle; // a toggle bit

void setup() {
  lcd.init(); // start LCD
  lcd.backlight(); // backlight on
  lcd.setCursor(5, 0); // cursor on first row, seventh column
  lcd.print("Hello,"); // print message on LCD
  lcd.setCursor(5, 1); // cursor on second row, seventh column
  lcd.print("World!"); // print message on LCD
}

void loop() {
  if (millis() - timer >= timeout) { // wait for timeout
    timer = millis(); // reset timer
    if (!toggle) // check toggle bit
      lcd.noBacklight(); // backlight off
    else
      lcd.backlight(); // backlight on
    toggle = !toggle; // toggle bit
  }
}

```