LCDInfo.com

Ok, well... I now have my hands on a Planar display I was talking about in a differant thread...

It's a 320 x 256 pixel EL display with lovely small dot pitch for a nice high res clear looking display.

I have a feeling that this display isn't going to be as easy to drive as I thought it might be though. The input to this display is video with Vertical and Horizontal sync pulses, and a pixel clock. maximum pixel clock frequency is 25 Mhz. Max Vertical sync is 75 Hz.

Henri, would this be a hard or easy driver for someone to work on? Here's the basic datasheet http://www.planar.com/Products/docs/IBU/current_manual/el/mn-planar-el320-256-f6-fd6.pdf if anyone feels like attempting a driver. Just wish I could program.

On the up side... with a driver written for this display, you could also connect a large variety of other displays, such as older monocrome CRT monitors, and the small format lcds that are video input driven...

Anyway, here's hoping...

_________________
Syridian,
http://syridian.com

That interface is similar to many lcd's without controller. But still it's not same as the most common ones and because of this I can't think of a controller that would be suitable for this one.

Some Planar displays have internal framebuffers which might allow even pretty slow drive signals like LPT port (no idea if it would work but it has crossed my mind when seen this in the Planar datasheets) but this one doesn't seem to have one so connecting straight to LPT port is out of question.

Building a interface for it should be possible though. Let's do some calculations.
The display takes the input signal one bit at time and it has 320x256=81920 pixels in a screen. With a refresh rate of 60 Hz this would make 4915200 clocks per second. So about 5 MHz. That is quite fast speed.
Many microcontrollers have hardware SPI interface that might be able to reach this kind clock speed. Besides just clocking the pixel data there is also some overhead to calculate and drive the VSYNC and HSYNC signals. Probably this could be done but this would just mean we can generate the required driving signal. If we'd like to make a usefull controller we would need large enough frame buffer. For 320x256 pixels this would be 10240 bytes. Philips has some ARM7 microcontrollers that have up to 64KB SRAM so maybe one of these could work. Of course there are also others that have large enough SRAM.
Of course there are some AVR's with external memory interface but I don't know if the speed would be enough with that.

Alternative option could be making a simple controller with a CPLD and 62256 SRAM for example.

The Planar display also has option for taking in 2 bits at a time. This would then reduce the needed clock speed from 4915200 to 2457600 which is about 2.5MHz. But this would mean that the hardware SPI wouldn't attach to this.

So it can be done but takes some figuring out and development work.

Hmmm All seems too hard doesn't it? Sure... be an interesting project, but not one thats high on my priority list at the moment.

Thanks for the detailed explanation Henri. It is appreciated.

If anyone IS actually interested in taking on this project, feel free to contact me and ask nicely... and I may send you the display, specially if you have something worth trading.

_________________
Syridian,
http://syridian.com