NHD-C0216CiZ-FSW-FBW-3V3 Contrast Problems

garrybarton

• January 17, 2022 08:07

Some of the new displays we are getting have contrast issues, some are darker than others and hard to read.  Is there a way to adjust the contrast on this display without using a firmware change?  If firmware is the only way then is there some sample code I can get?

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  Cody J.

  NHD Staff

  • January 18, 2022 08:07

  Hello GarryBarton,
  
  What capacitors are you using in your current display circuit between C1+/C1- and on VOUT?
  
  Best Regards,
  Cody_J

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  garrybarton

  • January 19, 2022 08:07

  1uF   C0805   TDK Corporation   C2012Y5V1H105Z/1.25   445-1364-1-ND

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  Cody J.

  NHD Staff

  • January 20, 2022 08:07

  Thank you for the information.
  
  Try adjusting the contrast via the "Power/ICON control/Contrast set" and "Contrast set" commands first.
  Contrast is a 6-bit value.
  
  The following command sequence will switch to instruction table 1 and adjust the contrast:
  

  • "Function set" command: Set the IS bit is set high along with all other settings previously set using the "Function set" command in your firmware. Sending this command will switch to instruction table 1.
  • "Power/ICON control/Contrast set" command: This is where the two most significant contrast bits (C5/C4) are written to the display. Be sure to set the Bon bit high as well. (and Ion if you are using that functionality)
  • "Contrast set" command: Write the four least significant contrast bits (C3/C2/C1/C0) to the display.

  
  For example, to write a contrast value of 0x15, send the following byte values:
  

  • Function set: 0x39 (8-bit interface, 2 lines, instruction table 1)
  • Power/ICON control/Contrast set: 0x55 (Booster circuit ON, C5, C4)
  • Contrast set: 0x75 (C3, C2, C1, C0)

  
  All of these commands are listed on page 8 of the display's datasheet.
  
  Note: Don't forget to switch back to instruction table 0 using the "Function set" command if you use the commands in table 0.
  
  If you have any questions, don't hesitate to ask.
  
  Best Regards,
  Cody_J

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