Help with 240x64 graphic lcd. Can’t get it to turn on.

Nick Sjolinder

• April 06, 2024 22:06

https://newhavendisplay.com/240x64-graphic-lcd-module-fstn-display-with-white-backlight/ I am attempting to get this display working for a prototype and I can’t seem to get it to work. I have attempted connecting 5 volts to pin 3 and pin 2 to ground which does nothing. I am was thinking maybe it’s because the contrast (pin 4) needed some voltage but it seems to involve some kind of negative voltage? There is a small cord with a connector coming off the lcd module which I think is the negative voltage output? I suspect this is part of the equation. Most recently, I connected 12.5 volts to the contrast pin (pin 4) because it mentions 12.5 volts in the “electrical characteristics” section of the data sheet and the unit began to smoke so I clearly did something very wrong there. I have been able to get the backlight to work using a 3.5v power supply. Could you help me sort through this? I have no clue how to get it working but perhaps it has something to do with the negative voltage? I assume I will need to buy a new unit due to the smoke…

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• Official comment

  

  Engineering Support

  Community moderator

  • April 08, 2024 22:02

  Hi Nick,

   

  I am sorry to hear about the damage to your unit. If you are ever uncertain about your connections, we provide wiring diagrams in our specifications document for your reference. In this case the inclusion of the negative voltage can be confusing, but we are able to see that the display has its own built in negative supply VEE (Pin 9) from the Pin Description table on page 4 of the specification. Following the wiring diagram, the -7V  needed for V0 (Pin 4) should be supplied from the output the output of a potentiometer connected between VEE (Pin 9) and GND (Pin 2).

   

  With regard to your other questions:

  1. The attached wire lead is the connection for the 3.5V backlight supply with the anode (A) corresponding to the positive backlight supply voltage and the cathode (C) corresponding to the backlight supply ground.
  2. The LCD Supply Contrast Voltage referenced in the Electrical Characteristics is defined by the difference of VDD (+5V) and V0 (-7V), or roughly 12V. If you would like further clarification as to why this is, you can find a more detailed explanation in the Contrast Voltage article located in our Knowledge Center.
  3. As we cannot verify what damage was done to your display, I would recommend that you first test your current display with the correct wiring before purchasing a new unit. As the damage to the display may not have affected the unit's functionality.

   

  I hope that you find this information helpful.

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