Displaying GUI on LCD with GPMC bus on OMAP3530 based board

Ashwini,

This is possible but you will possibly need to write a driver to support your particular display.

One option is to control the LCD from user space rather than write a true driver. This code would simply need to transfer the frame buffer to the LCD based on the specific LCD requirements. This is likely very simple, and most likely just simple setup then effectively a frame buffer copy from SDRAM to the GPMC.

It should be possible to configure the current frame buffer drivers should be able to be configured to match the LCDs size and color format, allowing more efficient transfer to the LCD.

It would be necessary to decide when to actually update the LCD since there will not be a continuous update as with a regular raster LCD. This could be either periodic, or when some frame buffer changes are completed. The simplest is to just do this periodically, but does introduce the possibility of image tearing if the LCD update is triggered in the middle of a frame buffer update operation.

The OS and GUI manager simply write to a frame buffer and do not care what you do with this memory afterwards.

BR,

Steve

Thanks steve,

I got some idea from your reply, but as i am writing LCD driver first time, it would be better if you can send link where this is explained in detail.(using frame buffer driver without DMA)

Regards,

-- Ashwini

Ashwini,

This is not really documented anywhere specific. The best place to get support and help with writing and modifying drivers is the Linux forums and/or open source community.

BR,

Steve

Thanks for your reply,

As our LCD is connected to GPMC, whether read-write signals are taken care (asserted) by GPMC or manually we have to set/reset.

--Ashwini

Can you send me the data sheet for the LCD you are wanting to use please?

BR,

Steve

THanks,

I have herewith attached the LCD datasheet for your reference.

--Ashwini

Ashwini,

There should be no issue connecting this LCD to the GPMC. It could also be connected via SPI or via the parallel digital video port.

Using the GPMC will require a specific driver to be written but will give you the best power consumption since the LCD will only need to be updated when the image changes.

Using the parallel digital output would allow you to use the existing drivers with only slight modifications (simply change the resolution) but will use slightly higher power in the LCD.

BR,

Steve

Hi Steve,

I am also having a similar situation. I am using a dot-matrix LCD for my project where I have interfaced the LCD with OMAP DM3730 processor via GPMC. I have gone through the TRM of the same and could not find anything as to where to begin with for the driver or the user space application

"This code would simply need to transfer the frame buffer to the LCD based on the specific LCD requirements. This is likely very simple, and most likely just simple setup then effectively a frame buffer copy from SDRAM to the GPMC."

Could you tell me about WHERE should I be looking at for the frame buffer? I could not find any fruitful information about this from the TRM.

Has this technique been implemented before? Please Help.

BR,

Harshit