Best display interface for embedded project

[Guest]

Hi,

I want to add a industry standard interface to a project I'm creating, is there a standard for display output to TFT or LCD, like I2C for display?

Thanks

Steve.

[PCM programmer]

You need to specify the type and resolution of LCD that you want to use.

For the simple 16x2 character LCD, the 4-bit, 3-control line interface
is standard.

[Guest]

it's for a graphical display not text, the problem I'm looking for the norm (7"ish) becuase I don't know about these displays I don't want to say XXX x YYY and find I picked a abnormal size and it is either hard to interface with or costs a arm and leg.

I take it the there is no real standard then that most TFT / LCD manufacturers use then?

[Douglas Kennedy]

Some observations on Graphical LCD's.


The human eye in order to not see the LCD screen appear to ficker requires a refresh rate in the order of 60 to 80 times per second.
Now suppose we are looking at a 640X480 monochrome screen that means we need to set or clear 24,576,000 bits per sec at 80hz.
3 million bytes per sec means a controller and memory
to support the LCD is a good idea.
The memory will need to be able to write and read in under 100ns
The LCD will need a bias supply
LCD's are often split screen or quarter screen.
EX In split sreen 4 bits are written to the upper half at the same time 4 bits are written to the lower half.
A solution I have used is to use a CPLD ( Ex Xilinx 9500 series)
An HDL language program is written to turn the blank 9500 into a controller specifiic to the LCD.
The CPLD is instructed to accept DMA requests from the PIC to the LCD screen memory via a gated 8 bit port. When not accepting data from the PIC the CPLD takes care of the LCD refresh from the memory.
Now if this sounds a bit bothersome it is..thats why it's better to get the LCD with the controller built in. Unfortunately the displays often don't come with the controller and often it is hard to get any specs from the LCD manufacturer.
Ex.
I have Hitachi LMG 9300XUCC LCD's and I still haven't found any documentation for them.

[Guest]

Is CPLD this interface I'm looking for then, if I added a CPLD interface would I have access to XX displays?

Thanks

[Guest]

Like I said I'm new to displays! I have looked and CPLD is not an interface but just a acronym for "Complex Programmable Logic Device"

The search goes on for a specification for a connector I can add to allow a display to be added at a later date is a simple RS232 the answer? than find a controller board with RS232?

Thx

[Guest]

Like I said I'm new to displays! I have looked and CPLD is not an interface but just a acronym for "Complex Programmable Logic Device"

The search goes on for a specification for a connector I can add to allow a display to be added at a later date is a simple RS232 the answer? than find a controller board with RS232?

Thx

[Konrad]

As PCM programmer replied, what size display?

The CCS glcd.c driver is for the ks0180 which drives 128 x 64. Using characters of 5 x 7 plus gaps gives 8 rows by 21 chars of text. Powertip and Crystalfonts both produce LCDs that are compatible.

There are other common driver chips of a similar type e.g. T6963C. The SED1335 or similar require extra ram, but can drive bigger resolutions.

You need to consider size, resolution, how much text, how much graphics, colour - full colour or monochrome colour(black/gray,white/black,white/blue etc), current consumption (is this portable), backlight requirements.
Find a display you like and then think about controlling it.

Without more specific details it is very dificult for anyone to give advice.

It is not advisable to leave the display as an addon - or at least reserve a minimum of 12 pins, prefferably 1 full port.

[Guest]

Sorry,

I suppose a 7" graphic TFT would be the biggest

Thx