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Author Topic: LCD busted (Help knowing what I did wrong!)  (Read 1051 times)
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Hi, I bought an LCD from sparkfun electronics I got it to work just fine but 2 minutes into this the LCD burned out or something, all I know is it  isn't lighting up anymore when I connect ground and 5V cable. The datsheets are here http://www.sparkfun.com/datasheets/LCD/GDM1602K.pdf   I connected 5V cable to pin 2 and ground to pin 1 in the LCD.
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quick answer from a newbie:

>all I know is it  isn't lighting up anymore when I connect ground and 5V cable

When you say "lighting up", do you mean you had the backlight working before with the connections you describe? Or simply that characters or gray or black squares were appearing?

If previously you had character blocks appearing, and its those that have now disappeared, it's possible that nothing's wrong with your LCD, and that you just need to adjust the contrast (V0) going in to pin 3.
The LCD tutorial shows you how to do that:
http://www.arduino.cc/en/Tutorial/LCDLibrary

If instead you're saying you just got the backlight to work, then perhaps you've mistaken pins 15 and 16 for pins 1 and 2.  According to the datasheet you referenced, the backlight comes on if you supply +4.2v across pins 15 and 16 (with 15 gnd and 16 +4.2v).  These 2 pins are at the other end of the module from pins 1 and 2.  If you did mistake the two sets of pins then your described wiring would have wired the backlight with inverted polarity.  I don't know if that'd damage the backlight or whether it's protected on that module.

Hmm, I've re-read the datasheet and the "features" section suggests that the backlight can also be driven from pins 1 and 2, though the pin connections section doesn't.  I'll leave my original thinking about the backlight wiring intact for now, but please take it with a (further) pinch of salt.

Tell us how much you had working before, and describe all your connections to the LCD.

p.s. You don't normally have to wire up the backlight to get the LCD working.
« Last Edit: November 26, 2006, 01:10:38 am by neillzero » Logged

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naw neither the characters nor the backlight is lighting up... they were, i had the LCD resting on on top of the arduino while i  went to get more wires when i came back i saw it was off i thought one of the cables had moved so re wired them all up and it still didn't work, B4 I left to get more cables the squares were turning on
« Last Edit: November 26, 2006, 11:24:18 am by R2_ » Logged

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I've used several of the LCDs from sparkfun that have backlights with both the regular arduinio and arduino mini.

It took me a (way too) long of time to figure out that the PDF pinout spec has the backlight + and - reversed.  The document is wrong - the bottom of the circuit board labels the + and - and the silkscreen is correct.  I've used both the blue backlight and red backlight devices from Sparkfun and the problem with the documentation exists with both.  

You should be able to see a very bright light at the right end of the device, underneath and partly extruding from the right under the lens, when it's working.  Without that backlight working correctly, the characters are barely discernable and only at certain angles.

In the process of figuring out the polarity issue with the documentation, I had the backlight hooked up backwards - for quite a bit of time while I was trying to find the issue.  Once I sorted it out, it fired up fine, so having the polarity reversed didn't seem to cause it problems...it still worked afterwards.

Also, as an FYI, I didn't use 4.2v, I just wired the backlight to 5v.  Perhaps that will shorten the life of the display, I don't know, but it works fine and I've run the display for days without any issues.

Anyway, that was my experience with these devices for what it's worth.
« Last Edit: November 27, 2006, 03:22:49 pm by landon » Logged

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well it was working and I've tried it on both sides and all to try to make it work again but it doesn't. My other theory for why it messed up was I had it laying on top of the arduino board so I suspect that maybe one of the metals touched a part in arduino with really high voltage.... just a thought tho I really don't know where I messed up it was working I left for a while when I came back 5 minutes later... it was busted and wouldn't light up.
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he's looking at you, kiddy...
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But is your arduino still working? did the display get its power from the arduino or from a separate power supply?
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