16x2 I2C LED: Black boxes on right side

Other Hardware Displays
1

My LCD1602 (With I2C) is outputting only half of what I want, with the right side being taken over by black boxes.

Code:

#include "Arduino.h"
#include <Wire.h> 
#include <LiquidCrystal_I2C.h>
#include <DHT.h>
#define DHTpin 2
#define DHTtype 11

DHT dht(DHTpin, DHTtype);

LiquidCrystal_I2C lcd(0x27,16,2);  // set the LCD address to 0x27 for a 16 chars and 2 line display

void setup()
{
  lcd.init();
  Serial.begin(9600);
  Serial.println(F("Sensor Init"));
  dht.begin();
  lcd.backlight();
}


void loop()
{
  Serial.println(dht.readTemperature());
  Serial.println(dht.readHumidity());
  Serial.println();
  lcd.setCursor(0,0);
  lcd.print("Temp: ");
  lcd.print(dht.readTemperature());
  lcd.setCursor(0,1);
  lcd.print("Humidity: ");
  lcd.print(dht.readHumidity());
  delay(300);
  lcd.clear();
}

20220207_143455
20220207_1434551920×2560 267 KB

It worked before. No idea what happenned. I replaced wires, recompiled, changed variables without success.

2

we hat a very similar topic here some weeks ago
https://forum.arduino.cc/t/lcd-trouble-20x4/950568/6

--> try another LCD.

3

Indeed we hat.

And as I explained there in #8, the faulty blocks on the right hand side indicates a fault in, or connections to "U2", the HD44100 "slave" chip to the HD44780.

700×700 71.2 KB

Sorry, dead display! :worried:

4

Great. I just hope its not expensive...

Any idea why it went out?

2nd edit: How do I repair it? I'm ok-ish at soldering.

5

Did you not buy it? :worried:

It is suggested that a lot of Aliexpress/ eBay stuff is rejects. And it is all Chinese low-level "consumer" grade material in the first place. Frankly, somewhat limited lifetime in general. :roll_eyes:

Got a really good surgical microscope? :grin:

7

I did several positive transactions with this Seller on Aliexpress. If you check the price for the combined LCD+Expander offer, it doesn't make sense so much to desolder yours.

8

$10.37 (Australian) shipping?

Not so sure about that! :roll_eyes:

9

is the thread owner Australian? I don't know. Shipping to Austria was fine.

10

I would be curious if the hd44780 library hd44780_I2Cexp ioClass diagnostic I2CexpDiag, detects anything wrong with the display.

--- bill

13

What is "Yours" ?
Was this response to me about I2CexpDiag?
If so, not sure what platform and board you are using but I2Cexpdiag should work on all platforms.

--- bill

15

It appears you are using platformio to do the build.
I don't know anything about platformio but it doesn't seem to process the sketches the same way the IDE does.
It appears to not be automatically creating prototypes for forward referenced functions.
This is a serious limitation that will cause failures on quite a bit of existing Arduino code.

Use the Arduino IDE and it will work.

--- bill

18

Was the display working properly when the diag test was run or did it still have half the screen with all pixesl on?

The diagnostic didn't see any issues. This means that data path to the LCD and all its internal memory and memory addressability is ok.

If there are stuck pixels as before,
there is some kind of h/w issue in the area that drives the pixels.

Maybe if you are lucky it is just a loose or improperly aligned zebra strip.
You might try pressing on or wiggling the LCD glass a bit on the display to see if anything changes
You could try re-seating zebra strip but it will be tough since the backpack is in the way of the clips so to mess with it you will likely have to de-solder the backpack.

--- bill

20

Yeah desoldring a header can be quite difficult without special desoldering tools.
I found that if I didn't have the tools, using dremel to cut all the pins to seperate the boards then desoldered the pins one a time on each board worked pretty well.

--- bill

21

The "Zebra strip" is not the problem. If it were, pixels would be entirely missing.

As explained in #3. :roll_eyes:

22

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