Newhaven Display Forum

Newhaven Products => TFTs => Topic started by: JRBrown on April 25, 2015, 08:03:07 PM

Title: ILI9341 Reading Display RAM
Post by: JRBrown on April 25, 2015, 08:03:07 PM
Does anyone have an example of reading the display ram with the ILI9341 controller?

I am using command 0x2E and cannot undertstand the data I read.

For example, I set the page and column to 0.
Then, using command 2C I write a red pixel.  So i write a 0x001F  (I'm using 16bpp)
Then I set the page and column back to 0.
When I issue the 0x2E command and then read 2 bytes, I get 0x00FC.

The reason I need to read the display RAM is that I'm trying to create bitmaps with "transparent" background.  My bitmaps will have a predefined transparent color. For every pixel I write, I would first see if it a transparent pixel.  If so, I need to read the display RAM and write the value of the current
pixel.

Any help is appreciated.
Title: Re: ILI9341 Reading Display RAM
Post by: Michael_L on May 04, 2015, 01:36:09 PM
We unfortunately don't have any code examples to read from the display's RAM, however all relevant information pertaining to the read cycle is available in the ILI9341 controller datasheet.  (See pages 30 - 32, 116)  Please also take note of the attached image below (from page 10).