Recently i had purchased a graphics Color TFT lcd with Touch screen from Taiwan. I m not sure abt the manufacturer of the lcd. The size is 5.7" with 640x480 resolution and 4- wire resistance interface for TSCR.
The LCD module is having Source and Gate Driver IC namely HX8250A and HX8678A. The output of the module has 18-bit parallel TTL interface(Red - R0 to R5, Green - G0 to G5, Blue - B0 to B5).Along with this HSYNC,VSYNC, DE,CLK are also present.
But i m not sure how to write a application program for the lcd module. As i dont have any datasheet of the LCD module i m not quite sure where should i start from and how to write the program for this?
Anybody can suggest in this??
One more note. You noticed that you didn't have any datasheet for the LCD, but you do know its pinout. That information had to come from somewhere. From my experience, datasheets for LCD modules don't have much more info that the part numbers of IC's used in them and required supply voltages. This information is normally sufficient to get them working.
As you said the there should be a graphics controller between the MCU and the GLCD. The graphics controller is given along with the LCD module as Source and Gate Driver IC separately.
It is to and from these IC's the controls and datas are going in and coming out.
I m intended to interface a SDRAM with the 16-bit MCU to hold the datas for the 640x480 resoultion and connect all other pins from the LCD module directly to the MCU.
As we had seen in normal LCD for example 2x16 LCD, we write the 8-bit data at the corresponding address given in the LCD, depending the RS and the Enable line.
In a similar manner is there any addressing for this color TFT to display the fonts or 2D-graphics?
An LCD with an RGB interface expects image data to be fed into it at 60 frames per second. That's 640x480x60=18430000 pixels per second. That's what a graphics controller does: it stores the image in the display buffer and refreshes the LCD at required frame rate by scanning the display buffer. Source and gate drivers are there to provide appropriate voltages and waveforms for the TFT panel. There are LCD modules with source and gate drivers as well as graphics controller built-in, but I've only seen them at up to 320x240 resolution. I've heard that some people manage to drive RGB data out of an MCU to an LCD with an RGB interface. Essentially, that would be emulation of a graphics controller. But that would consume a lot of CPU time and achieving good frame rate would be a challenge.
I just had a look at Epson GPU's. The S1D13781 looks very nice. Too bad it seems hard to buy. It's probably very new, hasn't reached many distributors yet...