Problem with LCD « Jee Labs Talk

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Problem with LCD

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tankslappa

Hi all, I've just built myself a pair of jeenodes. The RF test has worked perfectly. Now I'm having problems with the LCD module. I'm running the lcddemo sketch, the back light turns off and on, but that's all. No text. I unplugged the 2x16 display I bought from Jeelabs and tried the 4x20 display I have from Moderndevice, exactly the same happens, backlight flashes, no text.
I'm not sure if I've got something linked wrong on the lcd driver board, there aren't really any "if you want this, do this" instructions.
I have the logic set to +3 I have the light set to +3 I have the backlight resistor pad bridged.
There are some pads labeled SW, which I have done nothing to... no idea what they are.
Any ideas?

Posted 15/04/2010 23:47:23
tankslappa

Ah, just noticed something, if I turn the contrast pot all the way to the left I can just see some text if I look at the panel from almost horizontal next to it! It is so faint I can only see it says "Hello, world!" because I know that's what it says!
Does this help anyone think of a solution?

Posted 15/04/2010 23:51:58
jcw

For the 2x16 LCD from Jee Labs, try setting the logic level to 5V (i.e. PWR, assuming that's @ 5V).
The SW pins are a spare input or output (SW = switch). Optional. I've updated the page.

Posted 16/04/2010 00:28:31
tankslappa

Hi JC, Thanks for the prompt reply. I was just looking at the circuit diagram and wondering if I should jumper it to "Hi" to see if it helps. The only problem is I'm running on the 3 x AA battery holder, with NiMH batteries in it, so I'll only have 3.6v on PWR. I hope that give me enough contrast.

Posted 16/04/2010 00:36:34
tankslappa

Excellent, thanks Jean-Claude!
I have to wind the pot all the way round, the text is invisible for about 90% of the wipe, but all the way anti-clockwise is visible straight on with 3.6v from my NiMH batteries.

Posted 16/04/2010 00:53:34