NHD-3.12-25664UCY2 flickering

gambcl

• January 28, 2016 04:49

Hi,
I have just started playing with driving a NHD-3.12-25664UCY2 from a Raspberry Pi using 4-wire SPI in Python.

I have successfully got the display working and can draw onto it, however the display has very noticeable flickering.

I am pretty sure that this is controlled by some of the init parameters, which I think I copied from some sample code. Unfortunately this is my first time driving a display and all the various timing and voltage values went right over my head and I'm a bit worried about damaging the display if I just start guessing at values.

Could someone please talk me through how I would change the init parameters to get a solid display with no flickering?

These are the details I can remember (don't have the code in front of me):
- Input voltage 3.3v from Raspberry Pi
- 4-wire SPI interface
- SPI clock at 1MHz, just guessed at that value, how high can I go with this display?
- Internal voltage regulator

I saw a bunch of settings which I thought might affect the flickering but I have no clue what they mean and what affect they have on the display:
- VCOMH
- Phase length
- Display clock divider
- Display enhancement A
- Display enhancement B
- Precharge period
- Precharge voltage
- Contrast current
- Master contrast current
- Multiplex ratio

I did read the datasheet regarding these values but it just talks in pure voltages/timings and doesn't actually tell you what effect these settings have on the physical display. Some plain English for us newbies would be fantastic, I'm trying to learn how to pick up and drive these things so any clearer explanations on these more technical settings would go a long way.

Any ideas on what I need to change to get rid of the flickering?

Many thanks,
Charles

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  Michael_L

  • January 29, 2016 07:54

  I'm sorry but unfortunately we do not have such a guide explaining all the commands.  The controller's datasheet should have sufficient information for this.
  Here is a link to it: https://newhavendisplay.com/content/app_notes/SSD1322.pdf 
  
  In terms of the initialization, please use our example initialization sequence in the display's datasheet, page 12.  There is no flickering present with this initialization.

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  gambcl

  • January 30, 2016 04:37

  Thanks Michael, when I checked my initialization code it all matched the example, apart from the display clock setting. I changed that to match and the flickering has now gone. Nice stable display now.

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  jimmy_sayavong

  • February 24, 2016 09:54

  Can you post your initialization code here to see if I can duplicate your issue?

  
  I assume this is for SSD1322 controller, right?
  
  JIMMY

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