Hi everyone,

I am just enquiring to find out the basics on how to control a graphical LCD with an embedded system.

My knowledge so far reaches as far as using a PIC microcontroller controlling 16x2 LCD displays and the microcontrollers with the ARM architecture.

For my 3rd and final year in uni I am required to do a personal project of my choice. I just thought I would start enquiring now (project starts September 2007), so I have a better idea of what I'm doing or can't do for when the time comes.

I have an idea of creating some kind of embedded system that interfaces to the user using an LCD touch screen to control a desired application.

Could anyone aid me on where to begin. i.e. how do I get a graphical LCD to display graphics? Whenever I have controlled a 16x2 LCD I just send 8 or 4 bits of control data at a time and hey presto it displays what I tell it to. Now, my imagination leads me to believe that such basic control does not apply to a graphical touch LCD.

What kind of chips do I use to control a graphical LCD?

From just simple browsing I have noticed that there are graphical LCD controllers out there. What exactly do they do? Can they be controlled from simple microcontrollers such as PIC18F4620 or NXP LPC2129?

Any information anyone has about such an application would be most welcomed. You could say I'm just trying to find the road signs so I know what direction to head in.

Thank you for your time and assistance,

Rob

 

how do I get a graphical LCD to display graphics?

It depends on the specific display you are using. There are displays that already have integrated controllers onboard, these are controlled through the digital interfaces, which can be proprietary. The manufacturers will have datasheets showing how to interface and what data to send. An example is Sharp VGA display (LQ064V3DG01), do a search for item 1098278 at Farnell and have a look at the datasheet.

There are also naked displays, the ones without any controller onboard. You would be asking for trouble if you decide to go this route, and finding one to buy is also difficult.

First, you have to decide the resolution and the colour depth that you are interested in, then search for a suitable display. Hitachi and Sharp have extensive ranges to suit different needs.

Last, you could go with a VGA controller route and then obtain a cheap or used TFT monitor. This is potentially much cheaper and gives you flexibility in choosing the display.

From just simple browsing I have noticed that there are graphical LCD controllers out there. What exactly do they do? Can they be controlled from simple microcontrollers such as PIC18F4620 or NXP LPC2129?

They can be controlled from any microcontroller/processor. Although you have to keep in mind the speed (data rate) that the display need. For example, feeding a 8-bit colour VGA at 60Hz refresh means that you have to pump more than 18MB of data a second, and also need quite big screen buffer memory. You can alleviate this requirement by decreasing the refresh rate somewhat.

The touch screen requirement is somewhat more difficult. It is rare to find display with touch screen on the market. What I would suggest is to find an EPOS supplier, they usually have modules for this kind of display and obtaining one from them is always a possibility. It'd probably cost you quite substantially. The one that I have seen have a PS2 interface for the touch controller, and acted more or less like a mouse with an appropriate OS control. I'm sure it can also be custom controlled with a suitable microcontroller/processor. The datasheet would explain how to do this.

 

Hi n9352527,

Thank you for your response. I'm sorry for taking so long to reply, I have been away from my home for some time and access to the internet in my free time was quite difficult.
I shall read upon what you have said and re-open this threat when I get more time. Busy busy at the moment.

Thank you again,

Rob