I'm trying to print an int on both an LCD and the Serial Monitor, but its only being displayed on the LCD. The Serial Monitor is printing question marks.

Here is my Arduino code:

#include <LiquidCrystal.h>
LiquidCrystal lcd(1, 2, 4, 5, 6, 7);
int x = 10;

void setup()
  lcd.begin(16, 2);

void loop()
  lcd.setCursor(0, 0);
  Serial.print(x); // print Serial
  • reduce your code to print to serial monitor only and try again .... post your results .... note: question mark ? .... exclamation mark !
    – jsotola
    Commented Jul 8, 2018 at 0:10

1 Answer 1


If you are using clasical UNO, then pins 0 and 1 are Serial. Declaring lcd(1,... make LCD use the pin 1 too, so Serial is confused and garbled.

Use other pins for lcd and adjuct the wires acordingly.

  • 1
    @aloush You should select the green tick next to the vote button in the left if you think this answer solved your problem.
    – ArduinoFan
    Commented Jul 8, 2018 at 12:03

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