Programming LCD's

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Programming LCD's

Postby HARiS_P » Wed Oct 01, 2003 8:39 pm

I was wondering, how would you program LCD's and such. U know like on a calculator when u press numbers it shows up? or like have an LCD screen hooked up to something and have a program display various things on there? I'm sorry if the question is too vague, but if you need more clarification please ask.
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Postby Wizard » Wed Oct 01, 2003 9:57 pm

It's not that it's vague. Wait, yes it is. It's very, very vague. :p
You don't usually "program" an LCD. Often what you need to do is build a circut designed to drive the LCD based on a specific input, then build a circuit with some kind of processor capable of sending those inputs, and programming the processor to output what you want, when you want it.
Depending on the LCD you want to use, it could be easy or hard. If you're talking about the standard 7 line digit LCD found in calculators, then a chip already exists that'll do the selecting for you. It has 4 in lines (4 bit code) and 7 output, and depending on the input, it knows which parts of the LCD to light up. The more complex the LCD, the more complex the circuit.
Now I'm rambling. I'll stop now.
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so the circuit is referred to by the program..

Postby c0de » Mon Oct 06, 2003 4:14 am

So the LCD is not directly accessed the controller is and the controller knows what to do to the device it is controlling?
right?
so I never have to think of an LCD as an LCD in programming terms it is merely something connected to a controller that I have to "talk" to...
right?
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Postby Wizard » Mon Oct 06, 2003 8:06 am

If that's how it's set up.
You could hook an LCD directly to the parallel port, and control it with your computer, but then, if you wanted the number 7, you'd have to know which pins to light up, and the character with that binary representation. You'd also be limited to, at most, 8 pins, coresponding to the 8 on the parallel. An external device can just receive the code '7' and know what pins it decodes to (there's actually a chip, fairly cheap, that you can buy that'll do this for you), and can have a much larger resolution.
It all depends on the hardware. Simple ones might just be a bunch of wires and simple transistors intended to show only one character, while a more complex one might have a memory, a microprocessor, and be able to do all kinds of cool things like scrolling text and different colours and stuff.
A little bit of electronics study, and you could build your own controller.
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Postby HARiS_P » Mon Oct 06, 2003 2:07 pm

Yea I'm planning to go into electrical engineering. I've done a lot of small projects with electricity including solar panels, and one of the bigger achievements was a combat robot, something like battle bots (www.battlebots.com). Now I'm trying how to get output to an lcd screen for small things. For example have some sort of a radio controller and on the LCD it shows important statistics and such.

Well thanks anyways, I'm going to go and look more into it.
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Postby Wizard » Mon Oct 06, 2003 2:31 pm

My big achievement was for my grade 12 electronics project, I built a clock. That's the only reason I know what I do about LCD. They were actually low res LED displays, but that's only because the LCD were more expensive. The same principles apply. Shortly after I graduated, they scrapped the program, and threw out all of the electronics and junk. I was really ticked when I found that out. They chucked close onto $1000 worth of electronics if not more, most of which was still fairly good. I mean, there's not much use for a 6502 microprocessor anymore, but I'm sure they could have found a nice home inside someones battle bot.

I digress. Sounds like an interesting project. Good luck.
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