AM18X compatibility with LVDS LCD Displays via converter

Chuck Brodeur

Other Parts Discussed in Thread: AM1808, SN75LVDS84A, OMAP-L138, DA8XX

I'm looking at the option of using an AM1808 and may need to support LVDS LCD displays. It's not clear from the data sheet, reference manual, nor lcd user guide that the AM18X LCD interface is compatible with a converter such as the SN75LVDS84A.

I found a wiki page specifically for the omap 2/3 lcd connectivity but I haven't been able to confirm that the display driver in the omap family is the same as the am18X family.

Any help would be appreciated. Thanks.

over 13 years ago

0 Michael Williamson over 13 years ago

Expert 1985 points

Hi,

We've done a couple designs integrating a MityARM-1808 SOM (basically, an AM1808) as well as a MityDSP-L138 (same idea, uses OMAP-L138) with an SN75LVDS84A.

Pretty much it's a direct connect from the LCDC signals on the AM1808 to the serializer chip -- just watch that you get the data lines hooked up to the correct bit lanes for whatever display you are using (we used a family of NEC VGA and SVGA displays that were thankfully compatible).

You'll need to tweak the linux driver to support whatever resolution/timings called out by the display. The driver, for linux at least, is implemented in the drivers/video/da8xx_fb.c file. As far as I know, only the OMAP-L138, AM1808, and the AM335x chips use this driver -- there may be more that I am unaware of. There is a known_panels array in the file that has a list of timings that you can call for from your platform file. It'd be nice if the driver supported a command line argument for VESA timings (most LVDS panels support VESA timings from what I've seen so far). So, you'll have to tinker a bit with the kernel code to get your system going.

-Mike Williamson

www.mitydsp.com