Go Down

Topic: LCD 20x 4 only shows white box on line 1 and 3 (Read 2288 times) previous topic - next topic

Eurnis123

anyone know the problem cause? why this 20x 4 LCD got this problem that at 1st use ok , yet few hours it become only shown 2 lines at line 1 and line 3... why? anyone know why it happen n how to solve it... kindly neDDDDDD ur help..... thx.... T.T

Eurnis123

https://forums.adafruit.com/viewtopic.php?f=47&t=27122#p139232


this guys also faced same problem with me... why so many problem related to 20 x 4 LCD...hmmm... help me... i dnt want be like this... T.T   

sterretje

#17
May 23, 2016, 04:39 am Last Edit: May 23, 2016, 04:42 am by sterretje
Did you try the potentiometer as suggested by @cattledog?

There are two things that can be faulty.

Display
Arduino

Disconnect everything except the display
Run a test sketch that displays something on the dislay. Does it work correctly?

If not, move the display to totally different pins. Try again.
Still not working, there is a good chance that the display has died.

Note that this is not conclusive. Due to incorrect wiring with the diode, you might have done harm to the Arduino.

To check that, you need to test all pins of the Arduino board.

Disconnect everything.

Write a sketch that sets all pins to OUTPUTS and LOW (in setup()); measure the voltage on all pins (use a LED and resistor (between pin and GND) if you do not have a multimeter). All should read around 0V or LED should be OFF. Next modify the sketch and set one pin high. Measure again; the one pin should between 4.5V and 5V or the LED the LED should light up.
Repeat for next pin.

Next write a test sketch that reads a pin and activates the LED on pin 13; use INPUT_PULLUP for pinMode. Use a wire or a button to short the the pin to GND. Is it detected?
Repeat for all other pins.

Good luck; it's difficult to check those things from where I'm sitting ;)
If you understand an example, use it.
If you don't understand an example, don't use it.

Electronics engineer by trade, software engineer by profession. Trying to get back into electronics after 15 years absence.

Eurnis123

Hi sterretje, I had already try the potentionmeter as said by cattledog. it is just adjust the contrast of the white box from disappear till clearly seen yet that not solve the problem... it does not matter anywhere...hmm....   :(

I got change other pins for the LCD and run simple sketch to it, results stills same.. yet when i read other ppl  with the same problem as mine.. he said my LCD not died coz if died the LCD will not display anything... really? ...  the link r as below:

http://arduino.stackexchange.com/questions/17402/what-could-make-an-lcd-stop-working-permanently-after-being-connected-for-5-seco

https://forums.adafruit.com/viewtopic.php?f=47&t=27122#p139232


Then , I got check the arduino board to test the motor running control by its speed n the motor run as usual it been n I also gave to my friends use for testing him project, n it works as usual.. so can concluded no problem of arduino.

The problem list by other ppl also faced the problem i did n seem no one know how to solve n telling what is happening... hmm...  :(  :(  :(

Last but not least, thank u very much for ur respond n help me lead into the correct ways solving problem...  :)  :)  :)

cattledog

Quote
he said my LCD not died coz if died the LCD will not display anything... really?
That is not correct.

There are two aspects to the LCD. There is power, backlight, and contrast controlled by lcd pins 1,2,3 and 15,16. It appears that you have everything correct here, as the back light is on and you can modify the contrast with the resistance from pin3 to ground. These functions of the display are independent of the arduino.

The second aspect is the "controller" which controls the display of the characters. The controller is addressed by lcd 4,5,6 (RS,RW,E) and data pins D4,D5,D6,D7. RW on pin 5 is grounded, and the others connected to the arduino through pins declared in the "constructor".
Code: [Select]
LiquidCrystal lcd(A0, A1, A2, A3, A4, A5);

The second part of your display is what is not working. If you are wired correctly to the arduino pins declared in the constructor, and the wires, breadboard, connections, etc are good the display should show characters. If the display was working and then quit, its possible that it is broken. If you have changed all the control wires, resoldered connections, moved things on the breadboard, and verified working pins on the Arduino the controller in the display is likely broken.

 

Eurnis123

thx u so much cattledog...  :)  :)  :)

i very appreciate ur help..., i have already changed all the control wires, re-soldered the connections, moved things on the breadboard, and verified working pins on the Arduino n the LCD still shows line 1 and line 3 with white box only. I also think the LCD is broken,  :(  :(  :( will gonna replace it.. thx for ur nice explanation on the fact of LCD "died"... I learn a new thing 2day...   :)

nani1234

I am also having this problem  1 and 3 lines are showing blocks.....anyone could help me plzzz......i want to complete my final yeaar project

sterretje

#22
Nov 12, 2016, 06:09 pm Last Edit: Nov 12, 2016, 06:10 pm by sterretje
I am also having this problem  1 and 3 lines are showing blocks.....anyone could help me plzzz......i want to complete my final yeaar project
I'm sure Eurnis123 bought a new one or swapped it under warranty; as he did not get back to us that it did not solve the issue, I suggest that you do the same thing.
If you understand an example, use it.
If you don't understand an example, don't use it.

Electronics engineer by trade, software engineer by profession. Trying to get back into electronics after 15 years absence.

Thunderer

Pins may have burnt or pin configuration (In program) is wrong. Just it is getting power.

erimads

#24
Feb 21, 2018, 04:59 pm Last Edit: Feb 22, 2018, 10:40 am by erimads
You have to set a 4x20 display up as a 2x40 lcd.begin(40,2)
then use curser as follows
line 1 0,0
line 2 0,1
line 3 20,0
line 4 20,1

regards erik

Go Up