ILI9341 LCD controller, does it have transparency ?

[snoopy]

The Solomon Systech SSD1289 LCD controller has a transparency option using a compare register so that when you write a pixel to the controller that matches the compare register it doesn't actually get written to the display RAM. This facilitates transparency which is useful for drawing fonts and sprites on different colored backgrounds etc.

Now it looks like all of the LCD display makers have switched from the SSD1289 to the ILI9341 for which I cannot find any way of facilitating transparency. Nor do I want to render the image in local RAM by the MCU and then write it out to the display memory because that is just going to consume lots of bandwidth even using DMA.

Has anyone had any experience with this LCD controller ?

cheers

[dmills]

I do not believe the 9341 does transparency, and I have crawled all over that datasheet (Warning, in parallel Hs/Vs mode, you cannot get it to do landscape mode scan, which is a PITA for video).

Regards, Dan.

[snoopy]

I do not believe the 9341 does transparency, and I have crawled all over that datasheet (Warning, in parallel Hs/Vs mode, you cannot get it to do landscape mode scan, which is a PITA for video).

Regards, Dan.

What a PITA. I rewrote the code to handle both controllers and realised there was no transparency mode on the ILI9341 so it behaves differently to the SSD1289

cheers
david

[dmills]

One thing I have learned about displays is to always assume the screen chip on glass will do the bare minimum (And that often in an insane way), that way when you have to change the screen because of component obsolescence (And you probably will have to), it is easy to fix. 

Hopefully you were not relying on DMA to do your blit operation, and have some ram left for an overlay mask?

regards, Dan.