Flickering NHD-0220CW-AY3

eyarg

• November 15, 2016 12:55

Hey NHD,

EDIT: after trying to catch the trigger for the flickering, I found it depends on the first char of the first line. a "tall" char causes flickering, a "short" char doesn't.
Common chars I found be "unharmful" are: acegmnopqrsuvwxyz-+=.
So far this theory is consistent. Anyone has a clue about the cause of it and maybe a solution?

Original:
The repetitive issue is that the display keeps flickering after some changing prints. The flicker is a row of dots for a split second and once it starts it won't stop until a power off then on. I still can't figure out the exact trigger that starts the flickering but it always eventually starts, and my application send new prints every 250 ms so that it starts pretty soon on system start.
My init routine is copied from the data sheet and is also compared to some examples from the web.
Here it is just in case:

RES = 1; //reset HIGH – inactive
delayms(1); //delay
command(0x2A); //function set (extended command set)
command(0x71); //function selection A
data(0x00); // disable internal VDD regulator (2.8V I/O). data(0x5C) = enable regulator (5V I/O)
command(0x28); //function set (fundamental command set)
command(0x08); //display off, cursor off, blink off
command(0x2A); //function set (extended command set)
command(0x79); //OLED command set enabled
command(0xD5); //set display clock divide ratio/oscillator frequency
command(0x70); //set display clock divide ratio/oscillator frequency
command(0x78); //OLED command set disabled
command(0x08); //extended function set (2‐lines)
command(0x06); //COM SEG direction
command(0x72); //function selection B
data(0x00); //ROM CGRAM selection
command(0x2A); //function set (extended command set)
command(0x79); //OLED command set enabled
command(0xDA); //set SEG pins hardware configuration
command(0x10); //set SEG pins hardware configuration
command(0xDC); //function selection C
command(0x00); //function selection C
command(0x81); //set contrast control
command(0x7F); //set contrast control
command(0xD9); //set phase length
command(0xF1); //set phase length
command(0xDB); //set VCOMH deselect level
command(0x40); //set VCOMH deselect level
command(0x78); //OLED command set disabled
command(0x28); //function set (fundamental command set)
command(0x01); //clear display
command(0x80); //set DDRAM address to 0x00
command(0x0C); //display ON
delayms(100); //delay

Any and all ideas are welcome.

Thanks,
Eyar

0

• 

  Saurabh_B

  • November 15, 2016 03:34

  Hi,
  
  Do you have a limit as to how much current your VDD line could supply?

  0
• 

  eyarg

  • November 16, 2016 12:04

  Thanks for the reply, there is no such limit, can you elaborate on why is this relevant?

  0
• 

  Saurabh_B

  • November 16, 2016 15:10

  The flickering can be caused by a lack of current being supplied to the voltage boosting circuit.
  
  Would it be possible to record a video of the flickering that occurs?

  0
• 

  eyarg

  • December 07, 2016 07:07

  Two examples of fickering:
  https://drive.google.com/open?id=0BwwBB8wZZUlxQS00U1paYXl6YkU
  
  https://drive.google.com/open?id=0BwwBB8wZZUlxSGVmOXdTYkItd3M
  
  And an example of my claim from my edit (first char of top line is lowercase):
  https://drive.google.com/open?id=0BwwBB8wZZUlxWlg2aVpBRTFQcjA

  0
• 

  pete_123

  • June 18, 2021 15:52

  I have almost exactly the same issue as above (same Newhaven OLED display). If I do a complete display write from the line 1 home position, I get a nasty brief display flicker which manifests as feint lines and dots. If I do as the original poster mentions, and either use a blank space as the first character of line 1 (or also generally a lower-case character) the problem completely goes and there is no noticeable flicker.
  
  Has anybody else had this issue, and are there any suggestions on what might be causing the problem?
  
  Many thanks for any input.

  0
• 

  dgwest

  • November 30, 2021 15:02

  I am experiencing the same issue; has anyone resolved this?
  
  My Vdd supply is a very solid 5V. I've even added an extra 22uF cap at the connector to help with any possible current surges.
  
  I am now blanking the display, writing my characters, then unblanking it as a work around. This produces a slower update but does not show the flickering bars/dots. I would like to know if there is hardware or init settings that will resolve the issue properly.

  0

Please sign in to leave a comment.