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Topic: LCD White Boxes (Read 569 times) previous topic - next topic

Rentaya

Hi! Im trying to replicate this build for a class. I checked my connections to make sure everything was good already as well. I only get white boxes to appear when I plug my Arduino into my computer. The servo motor runs as I can feel/hear it buzz when I plug it in. Im using the exact same code as in the linked page. Any ideas on whats wrong and what I can do to fix it so that the letters/numbers appear? Thanks

https://create.arduino.cc/projecthub/LoganSpace42/arduino-lock-box-0d52c0?ref=platform&ref_id=424_trending___&offset=6

Paul__B


OK, so you have the contrast adjusted more-or-less correctly.  Good start, but just a little hint:  There is a silly blunder that has passed through nearly all of the tutorials and project designs using these displays.  Removethe connection from one end of the contrast potentiometer to Vcc - 5 V.  This is a mistake; removing the wrong connection will make setting the contrast easier; easier still if you use a 1k potentiometer instead.

But that is not your problem.  We do not quite know what the problem is but it either wiring or code.


Hmmm.  I see a green wire from the R/W pin (5) on the display to row "a" of the breadboard.  This should connect to ground.

Rentaya

Wow, thank you! The LCD is actually working properly now! I wonder why the tutorial had it attached to the "a" connection where it seemed to be working in his video... Anyways thanks again for your help! :D

Paul__B

Yes.

That is not such a good tutorial overall.  He uses the buttons connected to Vcc with pull-downs.  Better practice is to connect them to ground and use pinMode of INPUT_PULLUP so you generally do not need the resistors, adjusting the code accordingly.  And he does not provide a proper circuit schematic.

I hope you have removed the potentiometer connection to Vcc and found the contrast adjustment easier.  This also saves a tiny bit of current which would be useful if you were running from batteries.

floresta

Wow, thank you! The LCD is actually working properly now! I wonder why the tutorial had it attached to the "a" connection where it seemed to be working in his video... Anyways thanks again for your help! :D
The author of that tutorial cleverly used the same red colored wires for the center connection of his potentiometer (LCD pin 3) and for the R/W line (LCD pin 5).

In another clever maneuver he put the two red wires one over the other where they passed next to the potentiometer.

To make absolutely sure that you can't unambiguously interpret the connections he used a low resolution photograph.

Don

Paul__B

To make absolutely sure that you can't unambiguously interpret the connections he used a low resolution photograph.
Yes, I noticed that.

And did I mention - no schematic, just a slightly confusing nodemap.

Not that I bothered about the resolution as I was just checking the order of the wires against the OP.

Geek Emeritus

the tutorial is written
the tutorial is published
the tutorial is wrong
nobody comes back and corrects the tutorial
All PMs will be deleted unopened due to arrogant argumentative pot stirring Malfoys.
 If you have not read "How to use this forum - please read", in particular: "7. If you are posting code or error messages, use "code" tags":  expect rude responses

Paul__B

I suspect no-one has told the author.

Note the statement (which the Javascript helpfully renders into all caps  :smiley-roll: ): "Be respectful and constructive - most Hackster members create and share personal projects in their free time".

There are presently no comments there.


floresta

the tutorial is written
the tutorial is published
the tutorial is wrong
nobody comes back and corrects the tutorial
It's only been up for 5 days.

Don

floresta

I suspect no-one has told the author.

. . .

There are presently no comments there.


There's one there now.

Don

Paul__B

Today at 11:57:03
...                           Depending on your time zone of course.  :smiley-lol:
Today at 11:57:43

I thought that was a really quick comment!

But it was indeed brief - and appropriate.  Why write it all again for his benefit when he can simply come here to see?

LoganSpace42

Apologies for the poorly written project. I adopted the post from work I had done for a school project and didn't adjust the formatting much. There may have been an error in my project that was never noticed by a grader. I will fix it as soon as I can. For the time being, I've noted to view this post in the beginning of the project. This is my first project posted to here, so apologies if it's not up to par. :)

Paul__B

Ah!  Great that we have you here.  :smiley-lol:

I would really appreciate it if you take note of my comment in my first paragraph of #1.  This silly blunder - connecting the potentiometer to Vcc when it should not be - is so pervasive that we need to have it corrected in as many places as possible.

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