LCD question

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LCD question

Postby william82 » Tue Dec 07, 2010 2:08 pm

HI everyone,

I just wonder that how I know LCD (liquid crystal display) is faulty?? Do I need to download some code in the microController to test it out or I just need to put the Voltage for the LCD?If I apply 5V to LCD,what should I expect to see on the screen of the LCD?

thanks
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Re: LCD question

Postby ABSF » Tue Dec 07, 2010 8:28 pm

I am sure you cant just test the LCD with a meter to see if it is faulty. Dont you have a friend with a working PIC board to test it for you? if no, my best guess is to get the SK40C with 16F877 and the UIC00B from Cytron, so you can test your LCD with a program.

Guys, is there any other easy way to test?

Allen
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Re: LCD question

Postby shiyan » Tue Dec 07, 2010 11:12 pm

Er... I got a method which I tested before. Supply the power 5V and Gnd, but you still need to connect the Vee to resistor divider for the contrast.... without any initialization, you should see black square on top of LCD row
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Re: LCD question

Postby kl84 » Wed Dec 08, 2010 11:17 am

By supplying power to the LCD alone may not be able to confirm the functionality of the LCD. I once came over a spoiled LCD which displays black box when i supply power to it and tuned the contrast. So it cant be sure.

What i usually do is download the sample code from cytron's SK40C page. Then connect the basic circuit on a breadboard or solder on a donut board. Since the schematic for SK40C is also given in the user manual, there should be no problem to get things right (for this reason, i consider SK40C an open-source product from cytron). After the circuit is done, program the microcontroller and you'll know whether your LCD is working. Time-consuming? Maybe u're right but i built this LCD tester board once and i use it for testing since then. After that i expand its function to test digital/analog input, uart, spi and so on ;)

ABSF WROTE: Dont you have a friend with a working PIC board to test it for you?

Anyway, this is the faster way to do it. Haha.
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Re: LCD question

Postby ABSF » Wed Dec 08, 2010 11:30 am

You didn't say where you get the LCD from. Is it a new LCD from Cytron? Or was it you grabbed it from some equipment?

I once interface my 68HC11 SBC to an LCD taken from a faulty Pay-phone. The LCD (16x2) didn't work with my SBC. After much research, I found out that the Vee needed a negative supply. Luckily my RS232 has a MAX232 and I took the -ve supply from it and it works. Without the -ve supply, the characters were actually there but the contrast was so low that you can't see the characters.

Allen
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Re: LCD question

Postby william82 » Wed Dec 08, 2010 11:41 am

Yes, the LCD I actually get from some one.

Anyway I think still need to write some code into it and thanks to you all helping and information.

Maybe SK40 is a good choice for me, didn't find it previously.

Thanks everyone
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Re: LCD question

Postby zhenning » Thu Dec 30, 2010 12:39 am

You can also use couple of switches and a debouncing circuit on the switch after the E pin on the LCD. That will provide you manual switching and testing of the lcd.
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Re: LCD question

Postby shiyan » Sat Jan 01, 2011 11:55 am

That's seem to be very canggih! hahah! I will not take my time to build that just to test the LCD :) the circuit itself is way to expensive compare to my LCD and time taken is too long.
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Re: LCD question

Postby zhenning » Sat Jan 01, 2011 12:42 pm

Hahaha.... shiyan, it will be cheaper than you LCD, XD only..

1 Nand
1 10 way switch
1 DPDT
1 7805 regulator
2 .1uF cap
1 10uF cap
1 PCB

that should be all you need :)
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