I’m using a brand new Arduino UNO together with a new HD44780 LCD (16x2).
The backlight turns on, but nothing else appears on the screen — no text, not even the dark boxes in the first line.
I followed the wiring and code exactly as shown in the example here
I’ve double-checked all connections several times, and also measured voltage and resistance — everything seems fine.
Still, the display stays blank.
At this point, I’m a bit lost about what could be wrong.
Any ideas or troubleshooting tips would be greatly appreciated!
please post pictures on which we can see your wiring. Each single wire must be visible.
Also post a clear picture of your soldering job on the LCD.
If you you are using a breadboard - also make a picture of the connected breadboard.
I measured the resistance between the contacts on the LCD board — there is no connection.
Code:
/*
LiquidCrystal Library - Hello World
Demonstrates the use a 16x2 LCD display. The LiquidCrystal
library works with all LCD displays that are compatible with the
Hitachi HD44780 driver. There are many of them out there, and you
can usually tell them by the 16-pin interface.
This sketch prints "Hello World!" to the LCD
and shows the time.
The circuit:
* LCD RS pin to digital pin 12
* LCD Enable pin to digital pin 11
* LCD D4 pin to digital pin 5
* LCD D5 pin to digital pin 4
* LCD D6 pin to digital pin 3
* LCD D7 pin to digital pin 2
* LCD R/W pin to ground
* LCD VSS pin to ground
* LCD VCC pin to 5V
* 10K resistor:
* ends to +5V and ground
* wiper to LCD VO pin (pin 3)
Library originally added 18 Apr 2008
by David A. Mellis
library modified 5 Jul 2009
by Limor Fried (http://www.ladyada.net)
example added 9 Jul 2009
by Tom Igoe
modified 22 Nov 2010
by Tom Igoe
modified 7 Nov 2016
by Arturo Guadalupi
This example code is in the public domain.
https://docs.arduino.cc/learn/electronics/lcd-displays
*/
// include the library code:
#include <LiquidCrystal.h>
// initialize the library by associating any needed LCD interface pin
// with the arduino pin number it is connected to
const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
void setup() {
// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
// Print a message to the LCD.
lcd.print("hello, world!");
}
void loop() {
// set the cursor to column 0, line 1
// (note: line 1 is the second row, since counting begins with 0):
lcd.setCursor(0, 1);
// print the number of seconds since reset:
lcd.print(millis() / 1000);
}
If you need any further details, please let me know.
The variable resistor is connected no correctly, power is supplied to the outer terminals, and the signal from the middle terminal goes to the display.
When using Uno it is best to use shields. Uno is designed to accept shields, it is not designed to work with breadboards. Other Arduino models such as the classic Nano are designed to be plugged into breadboards.
I would recommend switching to Nano, use a larger breadboard (or 2 breadboards clipped together) and solder PCB header pins to the display so that it can also be plugged into the breadboard.
Then use solid-core hookup wire, cut to length and laid flat to the breadboard, for the connections. Use several colours as you please, but consistently, and reserve black for ground and red for 5V.
Because the Pin on the potentiometer, which is connected to 5V is marked as "2", for some reason I thought it has the be the middle Pin, because 2 is between 1 and 3, which in this case is obviously wrong.
I know it’s a bit messy — I just set it up quickly for a few tests. Thanks a lot for the tips on how to improve it and also for pointing out the I²C adapter!
I agree that the schematic that you worked from is confusing.
If you look at the inner workings of a potentiometer, you can see that the wiper connects to the centre pin on the type of potentiometer that you have.
