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Support Forum » LCD Broken?

May 22, 2009
by GordonChil
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I just received this kit today. I've been able to successfully flash the IC and even load the iphone rc car project and give that a whirl (very cool).

However, I'm having trouble with the lcd screen. I've compiled and loaded the "initialload.c" program into the chip, but there's no response from the lcd display.

I noticed also that in the code there's a small instruction to turn on and off a LED. So I hooked up an LCD to the particular pin that was coded. The LED turns on and then off as expected.
So... my guess is that either:
1. The code I'm using is newer than the instructions on my NerdKit pdf. (or vice versa)
2. My double and triple checked wiring is somehow wrong.
3. The display is bad.

Is there updated code for the lcd or initial load program? Or is there some way for me to test to make sure the display works properly?

Thanks much,

May 22, 2009
by GordonChil
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Found the problem. The first set of instructions for the LCD hook up steps didn't say to do anything with pin 3. I had hooked it up anyways because I saw that the picture did.

I read the troubleshooting steps and saw that pin 3 on the display adjusts the contrast. I then double checked the resistor and the wire going to it, I saw that the resistor was plugged into the wrong spot on the board. After fixing that, the display lit right up.

Now having read further I see that there are instructions for this pin. It pays to read the documentation.

Very awesome kit.

May 22, 2009
by mrobbins
(NerdKits Staff)

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Maybe we should make the contrast pin more clear in the instructions, but it's great to hear that you solved the problem!


August 05, 2010
by kle8309
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Hi, I was doing the led blinking experiment and accidentally found that PD2 is giving out 2.2V. I tried the code on two different mcu's.

Is this normal?

August 05, 2010
by hevans
(NerdKits Staff)

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Hi kle8309,

PD2 is one of the LCD pins. If the LCD is on and data is being sent to it, then this pin is going to be toggling on and off to send the data. Your multimeter is much slower than this changing signal so it is only showing you the average. It is not surprising you are reading 2.2V if you are measuring this with a multimeter.


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