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Support Forum » Checking oscillator/capacitor/etc

November 30, 2010
by codebx
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So, I finally got the initial nerdkit project functioning after programming the MCU, and everything appeared appropriately on the LCD. I took in the kit to work, carrying it in a multimeter bag (made out of cotton and some other material - static electricity, maybe?), and when I turned it on, the LCD fails to come on. I am still able to write to the MCU, and everything seems to be okay when using 'make,' but I just can't get the LCD to come back on again like last night.

Is there any way to check if the oscillator is bad or if the capacitor is bad or if I fried some other component? It's unfortunate that the kit only comes with one of the .01uF capacitors and one oscillator. So, for what it's worth, I have an LED in pin 27 of the MCU and ground, and it blinks once when the SPD switch is in 'run mode,' so I'm under the impression that at least the MCU isn't busted. Any ideas what else to check? The wiring seems flawless still from last night.

November 30, 2010
by Rick_S
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If you can write to the mcu, then the chip is functioning. If the crystal were a problem, the chip would not program. I'd check connections. Most likely something came loose or shorted against something else. Secondly if running on battery power, replace it with a new battery. The contrast resistor on the LCD might be a good area to look as well.

If you can't get it, post a good close overhead photo showing all the wiring. That helps a lot in diagnosis.


November 30, 2010
by codebx
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Thanks for your help, Rick. :) I disconnected the LCD completely and reconnected the positive, grounds, and contrast, and nothing at all shows on the lcd, so I went ahead and purchased a new one.. I honestly think somehow static electricity got to it from bouncing around in that multimeter bag. Lesson learned!

December 01, 2010
by BobaMosfet
BobaMosfet's Avatar

whatever you do, DON'T throw the LCD display away, until you know for sure it's bad. I agree with Rick, it sounds like a contrast issue. It might be a capacitance issue, or something else trivial. Those are fairly sturdy unless it got twisted.


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