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Author Topic: mjkdz I2C - modify lcd constructor  (Read 1575 times)
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Here's the photo's.


* 20140312_155124.jpg (1573.24 KB, 2560x1920 - viewed 19 times.)
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LCD connected to Arduino and the backpack.


* 20140312_183335.jpg (1667.67 KB, 2560x1920 - viewed 25 times.)

* 20140313_220223.jpg (1580.67 KB, 2560x1920 - viewed 26 times.)
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exact same one I have, did you try the jumper wire from GND to Pin 3?   I looked at the solder job, kinda looks like you heated just the pins and not the lcd board , the lcd board should have alot more solder on it.
« Last Edit: March 13, 2014, 03:28:10 pm by jasit » Logged

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exact same one I have, did you try the jumper wire from GND to Pin 3?
Clearly the jumper test is not needed. You can see pixels on the display.

In looking at the photos, I immediately see a few things.
- The orientation (pin 1 location) looks correct
- The pot is a multi turn pot so it may take many turns to adjust the contrast.
- Many of the solder joints on the LCD module look bad.

With a good solder joint the solder should flow out and you shouldn't see any of the
gold around the hole where the solder is attached to the header pin.
The connections should look more like the connections on the backpack.

You need to go back over the solder connections on the LCD panel to get
the solder to melt & flow out a bit more.

--- bill
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I can see at least two pins that have not been soldered. I think you need to take a close up photo of the solder joints so we can  see it from directly above instead of from an angle. Clearly the soldering has some "issues".
« Last Edit: March 13, 2014, 04:05:30 pm by raschemmel » Logged

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Quote
I looked at the solder job, kinda looks like you heated just the pins and not the lcd board , the lcd board should have alot more solder on it.
I hope you mean that some of the existing solder should be transferred to the board from the associated pin.  I don't think he needs much additional solder except possibly a tiny bit to provide new flux.

Don
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Well, let's see, the soldering isn't grand but it seems to me that there is in fact some solder flowing onto both the pin and the "land" on each of the pins.

We have backlight.

We have a row of "blocks".  This indicates that the contrast control is near the correct setting and it indicates that the display is not being initialised.  It is possible that the display could be initialised but the contrast was not set sufficient to permit characters to be displayed however if it were initialised, there would not be the row of "blocks".

The backpack is however responding with an address.  Either the backpack is not connecting to the LCD panel - but I cannot see that the soldering is that bad - or we do not have the correct descriptor.  There is clearly no point in proceeding further at unless and until the "guesser" sketch gives a result.
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There's really no point in suggesting that the soldering may be OK when the pictures clearly show that is is pretty poor. 

The presence of the backlight and the row of blocks indicate that the power connections may be satisfactory but the lack of proper initialization or response to the guesser indicate that one or more of the other connections is not satisfactory.


Don
« Last Edit: March 13, 2014, 09:53:41 pm by floresta » Logged

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Instead of debating whether or not the soldering is ok, why don't we request a redo of the photo with a close up of the soldering so we can see it better ?
psycho22,
If you don't mind me asking , how much experience do you have soldering ?
« Last Edit: March 13, 2014, 09:56:17 pm by raschemmel » Logged

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I agree that debating the soldering is probably pointless.
However, my suggestion would be to re-solder the joints rather than first
taking additional photos, posting them, and then having use look at them again
which might just cause us to say: "Well, I can't really tell, better just re-solder them".
We already know they look suspect.
I've been through this several times with others with connections that looked very similar
and re-soldering them fixed the problem.
I'd suggest re-soldering them and then if it still isn't working, then post the photos.

--- bill
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I recorded a video: http://videobam.com/jtRrB

The lcd constructors which makes the LCD blink 3 times but without characters on it are:
1) lcd ( 0x20, 4, 5, 6, 0, 1, 2, 3, 7, NEGATIVE)
2) lcd ( 0x20, 6, 5, 4, 0, 1, 2, 3, 7, NEGATIVE)
3) lcd ( 0x20, 6, 5, 4 0, 1, 2, 3, 7, POSITIVE)
4) lcd ( 0x20, 4, 5, 6, 0, 1, 2, 3, 7, POSITIVE)

2 of the 6 lcd constructors from guesser skectch only make on the backlight but without blinking.

P.S. And I soldered the pins one more time. smiley The I2C circuit now makes contact with the LCD for sure.

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So the lcd never displayed a constructor when it blinked 3 times ?
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No.
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I can only conclude your contrast is not adjusted correctly. Can you get a meter and measure the voltage on the contrast pin of the
lcd ? CAN YOU OR CAN YOU NOT CHANGE THE CONTRAST NOTICABLY ? (THAT MEANS CAN YOU MAKE THE SQUARES DISAPEAR
BY ADJUSTING THE CONTRAST OR NOT ? It is a YES or NO question .
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Unfortunately we can't see much the actual LCD display pixels from your video.

I'm with raschemmel.
It is likely that you have not properly adjusted the contrast pot.
It is a multi-turn pot and can take many turns to make changes.
You should be able to turn it to make all the pixels go off.
Turn it that far then turn it slight back up to make them just turn on again.
That is where the adjustment needs to be.

The little details really matter.
As I said before the proper constructor will blink the backlight 3 times and leave it on.
(Your sequence numbers are not the same as the sequence from the guesser sketch
as there are two other combinations that would be tried first)

Only 2 of your noted constructors could cause the backlight to blink 3 times
and leave it on..

I'm guessing that from your list, only #1 and #2 are the ones
that make the display blink 3 times and leave it on.
And only one of those is the correct one.

Based on past experience, it is more than likely the first
one on your list.


--- bill


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