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enter image description hereI was recently experimenting with 20x4 lcd display with my Arduino Mega board. The connections which I followed are shown in the picture attached. I am very much sure about the connections and code written in the Arduino IDE. Everything is compiled and uploaded properly on my board. However the problem I found is the 20x4 lcd display only shows two alternate block lines and nothing else! To resolve this I tried following things:

  1. I made sure multiple times the hard wire connections between Arduino and display and found all are as per requirement.
  2. I made sure the proper coding with initialization.
  3. I tried changing the value of 10KOhm pot in order to control the contrast setting of lcd.
  4. I made sure about connecting the R/W pin of lcd to ground.
  5. I tried replacing the lcd display with another same unit.

With above troubleshooting the problem still persists. Can anybody will suggest what could be the issue?

Suggestions are highly appreciated! Thanks and regards, VK

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    Two rows of blocks on a 20x4 is the same as 1 row of blocks on a 16x2. It's not initializing the screen. Either your code is wrong or the wiring between the Arduino and the screen is wrong (i.e., it has nothing to do with contrast). – Majenko Mar 24 at 13:30
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    I am very much sure about the connections and code written in the Arduino IDE. -- that cannot be the case. One of those two is wrong. Your wiring looks fine (from what you showed us), so it must be your code that is wrong. – Majenko Mar 24 at 13:53
  • Try wiggling the wires in the breadboard. Breadboard sometimes don't make a good connection with the wire. Could you post an image of your setup, and the code you uploaded? As you've already done everything I would normally suggest. – Gerben Mar 24 at 16:48

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