OLED Display Noise problem

[gunayburak]

Hello everyone ;

I've been working on a project which requires an LCD display then I decided to get an oled in order to free some pins also to ease the PCB design
and I purchased an OLED code named EA W162-XBLW (ICEWHITE) of Electronic Assembly but I have a disturbing problem with the LCD .. After I power the circuit up I can perfectly display all the characters on whereever I want on the lcd but there is an incredible noise moving all around the LCD in a form of a pixel , So far I have tried using capacitors even those larger ones and even added the define LCD command and data line parameters with several tries ,, but no lock so far .. Here I share the code and a picture ... I hope any of you had such a weird problem in the past and solved it ...


The code is for 16F1827

#config
 __CONFIG _CONFIG1, _FOSC_INTOSC & _WDTE_OFF & _PWRTE_ON & _MCLRE_OFF & _CP_OFF & _CPD_OFF & _BOREN_OFF & _CLKOUTEN_OFF & _IESO_OFF & _FCMEN_OFF 
 __CONFIG _CONFIG2, _WRT_OFF & _PLLEN_OFF & _STVREN_OFF & _BORV_19 & _LVP_OFF
#ENDCONFIG


'-------------------------------------------------------------------------------
define OSC 4
OSCCON=%01101010    'OSC is @ 4 MHZ


'------------- LCD DEFINES ------------------------
DEFINE LCD_DREG PORTB 'LCD data port 
DEFINE LCD_DBIT 4 'LCD data starting bit 0 or 4 


DEFINE LCD_RSREG PORTA 'LCD register select port 
DEFINE LCD_RSBIT 7 'LCD register select bit


DEFINE LCD_RWREG PORTA   ' LCD read/write port
DEFINE LCD_RWBIT 0   ' LCD read/write pin bit  


DEFINE LCD_EREG PORTA 'LCD enable port 
DEFINE LCD_EBIT 6 'LCD enable bit


DEFINE LCD_BITS 4 'LCD bus size 4 or 8 
DEFINE LCD_LINES 2 'Number lines on LCD


'------------- LCD DEFINES -------------------------




'-------------------------------------------------------------------------------
PORTA=%00000000     :      PORTB=%00000000
TRISA=%00000000     :      TRISB=%00000000 
'ADCON0=%00000001    :      ADCON1=%10110000
ANSELA=%00000       :      ANSELB=%00000000
'OPTION_REG.7=0     
'-------------------------------------------------------------------------------
                                   


pause 500
                        
lcdout $FE,$28
lcdout $FE,$17
lcdout $FE,$06
lcdout $FE,$08
lcdout $FE,$01
lcdout $FE,$02
lcdout $FE,$0C
 
MAIN:
              
lcdout $FE,$80,"BU BiR DENEMEDiR"
LCDOUT $FE,$C0,"  iKiNCi SATIR  "


goto main

[LinkMTech]

Hi,

I would suggest writing to the LCD only when you need to update the display info.
Constantly writing to it in a loop without any kind of delay may be causing the problem.

pause 500
                        
lcdout $FE,$28
lcdout $FE,$17
lcdout $FE,$06
lcdout $FE,$08
lcdout $FE,$01
lcdout $FE,$02
lcdout $FE,$0C
lcdout $FE,$80,"BU BiR DENEMEDiR"
LCDOUT $FE,$C0,"  iKiNCi SATIR  "


Main:
 Do stuff
 IF something_new THEN Update_LCD

GOTO Main


Update_LCD:

 lcdout $FE,$80,"BU BiR DENEMEDiR"
 LCDOUT $FE,$C0,"  New data  "

GOTO Main

[gunayburak]

Hi,

I would suggest writing to the LCD only when you need to update the display info.
Constantly writing to it in a loop without any kind of delay may be causing the problem.

pause 500
                        
lcdout $FE,$28
lcdout $FE,$17
lcdout $FE,$06
lcdout $FE,$08
lcdout $FE,$01
lcdout $FE,$02
lcdout $FE,$0C
lcdout $FE,$80,"BU BiR DENEMEDiR"
LCDOUT $FE,$C0,"  iKiNCi SATIR  "


Main:
 Do stuff
 IF something_new THEN Update_LCD

GOTO Main


Update_LCD:

 lcdout $FE,$80,"BU BiR DENEMEDiR"
 LCDOUT $FE,$C0,"  New data  "

GOTO Main

Thanks for your response .But what if I need to display some sort of ADC reading which requires an instant update on the lcd continuously ?? You know how fast those readings may change ...

[LinkMTech]

You can only "see" so fast before it becomes a blur.
Try adding a PAUSE 33 in your main loop as it is, making it 30fps, just to test if the ghost dots go away.

[gunayburak]

You can only "see" so fast before it becomes a blur.
Try adding a PAUSE 33 in your main loop as it is, making it 30fps, just to test if the ghost dots go away.

Tried but still no luck

[Jerson]

Have you got your decoupling capacitors on board?

[gunayburak]

I tried adding pause 100 command right after the lcdout commands but the noise only got lowered just a little .. This is definitely not normal .. But when I apply 1000 ms of delay it almost stops making noise on the screen(there is still a little) ... But It musn't be that bad .. It is an oled and the datasheet claims parameters for write/read around nanosecs .. Where do I do the mistake ? , May it have anything to do with the LCD or a defective circuit component ... On the other hand I think It musn't have because It can display chars succesfully with a huge amount of delay periods ...

[pedja089]

That sound to me as bad PCB design and/or power supply. But sill could be bad LCD driver.
If long delays make artifact disappear, then capacitive coupling between LCD signals and power lines can cause that.
You can try test that. Add pull down resistor 1K to LCD Enable pin, and create easy way to disconnect LCD and resistor from PIC, as close as possible to LCD.

pause 500
                        
lcdout $FE,$28
lcdout $FE,$17
lcdout $FE,$06
lcdout $FE,$08
lcdout $FE,$01
lcdout $FE,$02
lcdout $FE,$0C

lcdout $FE,$80,"BU BiR DENEMEDiR"
LCDOUT $FE,$C0,"  iKiNCi SATIR  "
PAUSE 10000' Disconnect only LCD enable pin before pause timeout
Main:
lcdout $FE,$80,"BU BiR DENEMEDiR"
LCDOUT $FE,$C0,"  iKiNCi SATIR  "
GOTO Main

Display shouldn't update any more. If you see dots then 99% problem is with PCB layout, and decoupling.
If there is no dots on LCD then problem is with LCD.

[gunayburak]

That sound to me as bad PCB design and/or power supply. But sill could be bad LCD driver.
If long delays make artifact disappear, then capacitive coupling between LCD signals and power lines can cause that.
You can try test that. Add pull down resistor 1K to LCD Enable pin, and create easy way to disconnect LCD and resistor from PIC, as close as possible to LCD.

pause 500
                        
lcdout $FE,$28
lcdout $FE,$17
lcdout $FE,$06
lcdout $FE,$08
lcdout $FE,$01
lcdout $FE,$02
lcdout $FE,$0C

lcdout $FE,$80,"BU BiR DENEMEDiR"
LCDOUT $FE,$C0,"  iKiNCi SATIR  "
PAUSE 10000' Disconnect only LCD enable pin before pause timeout
Main:
lcdout $FE,$80,"BU BiR DENEMEDiR"
LCDOUT $FE,$C0,"  iKiNCi SATIR  "
GOTO Main

Display shouldn't update any more. If you see dots then 99% problem is with PCB layout, and decoupling.
If there is no dots on LCD then problem is with LCD.

Well ;

I did exactly as you asked me to do and as you say it's got to do with the lcd then ...

[Scampy]

Well ;

I did exactly as you asked me to do and as you say it's got to do with the lcd then ...

I don't have the same chip, but used an 18F4580 with a 2 x 16 LCD and just changed the lines to run the LCD from port B to suit the EasyPIC5 development board and I don't get any strange random pixels and I'm running the chip at 20Mhz so the switching is much faster, so it would suggest that it is your hardware that is at fault.

ASM 
  __CONFIG    _CONFIG1H, _OSC_HS_1H
  __CONFIG    _CONFIG2L, _PWRT_ON_2L  
  __CONFIG    _CONFIG2H, _WDT_ON_2H & _WDTPS_512_2H
  __CONFIG    _CONFIG3H, _MCLRE_ON_3H & _LPT1OSC_OFF_3H & _PBADEN_OFF_3H  
  __CONFIG    _CONFIG4L, _LVP_OFF_4L & _XINST_OFF_4L
ENDASM


DEFINE  OSC 20    

DEFINE LCD_DREG  PORTB                  ' LCD Data port
DEFINE LCD_DBIT  0                      ' starting Data bit (0 or 4)
DEFINE LCD_EREG  PORTB                  ' LCD Enable port
DEFINE LCD_EBIT  5                      '     Enable bit  (on EasyPIC 5 LCD)
DEFINE LCD_RSREG PORTB                  ' LCD Register Select port
DEFINE LCD_RSBIT 4                      '     Register Select bit   (on EasyPIC 5 LCD)
DEFINE LCD_BITS  4                      ' LCD bus size (4 or 8 bits)
DEFINE LCD_LINES 4                      ' number of lines on LCD
DEFINE LCD_COMMANDUS 2000               ' Command delay time in us 
DEFINE LCD_DATAUS 50                    ' Data delay time in us 

'-------------------------------------------------------------------------------
PORTA=%00000000     :      PORTB=%00000000
TRISA=%00000000     :      TRISB=%00000000 
'ADCON0=%00000001    :      ADCON1=%10110000
'ANSELA=%00000       :      ANSELB=%00000000
'OPTION_REG.7=0     
'-------------------------------------------------------------------------------                                 


pause 500
                        
lcdout $FE,$28
lcdout $FE,$17
lcdout $FE,$06
lcdout $FE,$08
lcdout $FE,$01
lcdout $FE,$02
lcdout $FE,$0C
 
MAIN:
              
lcdout $FE,$80,"BU BiR DENEMEDiR"
LCDOUT $FE,$C0,"  iKiNCi SATIR  "

goto main

Replaced the 20Mhz with a 4Mhz xtal and recoded and the display was fine.

[gunayburak]

I don't have the same chip, but used an 18F4580 with a 2 x 16 LCD and just changed the lines to run the LCD from port B to suit the EasyPIC5 development board and I don't get any strange random pixels and I'm running the chip at 20Mhz so the switching is much faster, so it would suggest that it is your hardware that is at fault.

ASM 
  __CONFIG    _CONFIG1H, _OSC_HS_1H
  __CONFIG    _CONFIG2L, _PWRT_ON_2L  
  __CONFIG    _CONFIG2H, _WDT_ON_2H & _WDTPS_512_2H
  __CONFIG    _CONFIG3H, _MCLRE_ON_3H & _LPT1OSC_OFF_3H & _PBADEN_OFF_3H  
  __CONFIG    _CONFIG4L, _LVP_OFF_4L & _XINST_OFF_4L
ENDASM


DEFINE  OSC 20    

DEFINE LCD_DREG  PORTB                  ' LCD Data port
DEFINE LCD_DBIT  0                      ' starting Data bit (0 or 4)
DEFINE LCD_EREG  PORTB                  ' LCD Enable port
DEFINE LCD_EBIT  5                      '     Enable bit  (on EasyPIC 5 LCD)
DEFINE LCD_RSREG PORTB                  ' LCD Register Select port
DEFINE LCD_RSBIT 4                      '     Register Select bit   (on EasyPIC 5 LCD)
DEFINE LCD_BITS  4                      ' LCD bus size (4 or 8 bits)
DEFINE LCD_LINES 4                      ' number of lines on LCD
DEFINE LCD_COMMANDUS 2000               ' Command delay time in us 
DEFINE LCD_DATAUS 50                    ' Data delay time in us 

'-------------------------------------------------------------------------------
PORTA=000000     :      PORTB=000000
TRISA=000000     :      TRISB=000000 
'ADCON0=000001    :      ADCON1=110000
'ANSELA=000       :      ANSELB=000000
'OPTION_REG.7=0     
'-------------------------------------------------------------------------------                                 


pause 500
                        
lcdout $FE,$28
lcdout $FE,$17
lcdout $FE,$06
lcdout $FE,$08
lcdout $FE,$01
lcdout $FE,$02
lcdout $FE,$0C
 
MAIN:
              
lcdout $FE,$80,"BU BiR DENEMEDiR"
LCDOUT $FE,$C0,"  iKiNCi SATIR  "

goto main

Replaced the 20Mhz with a 4Mhz xtal and recoded and the display was fine.

What can I say .. I am so unlucky with these OLEDs .. But thanks for your effort anyway ..

[gunayburak]

So any clue how to turn off this moving cursor .. Besides these moving cursor must be moving only at the first line of each character yet I see this noise on all over the screen ..

[OldMarty]

I recall most LCD's have a "cursor off" command? (i believe the OLED replacements for LCD's should also have cursor-off too).

Turn the cursor off at the beginning of your code, just after the LCD initialises. If you ever need to see the cursor as a prompt, then re-enable the cursor during that part of the code only.

hope this might help?

[Dave]

Do you have a data sheet available to view?

[gunayburak]

http://www.lcd-module.de/fileadmin/e...doma/olede.pdf

Here it is .. The model code name is :

• EA W162-XB

[CuriousOne]

I saw an article about these displays in Russian couple of months ago, that guy also had cursor issue and he dealt somehow with it. I will check my history later and let you know.