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Initialization Registers for RGB interface.

Hello, we're considering this panel in a new device and are currently attempting to evaluate if it will fit our needs.  Any help getting us through the evaluation would be much appreciated.  I have several questions.

Is there a document with sample register initializations for different interfaces?

    Specifically I'm looking to set Registers over SPI and then use the RGB parallel interface for the display.

    I believe I need to set IM[3:0] to 1101 to use the 3 wire spi interface and then set register 0x3a to 0x66 (and also the RCM[1:0] to 10 for DE mode.

    Having done that though, I still don't have a valid picture.  I got a white screen with a bar down one side.  I believe there are problems with internal (pcdiv, div et. al.) clock settings matching up to the frequency of my dotclk.

Also am curious for best image quality if we need to be setting the gamma registers.

Lastly, I wasn't able to find specs on the min/typical/max dotclk/FPS etc.

Thank you much for any assistance!


dennisjm's picture
November 28, 2018

Update I found the older post on here with minimalist registers to get the RGB interface up and that did end up working.  I just used the default timings from the ili9341 datasheet for 70fps.

Still looking for info on gamma settings and other possible registers to tweak visual appearance though as this needs to render video from a camera.

engineering_seacomp's picture
November 29, 2018

Hi dennisjm,

Here is a document that lists hardware connections for a few different interface options. The RGB serial column shows connections for using the 4-wire serial interface with RGB data. The only difference in your case would be the IM[3:0] bits (1101 for 3-wire as you know) and rather than using the serial D/CX pin you will tie it to VDD.

Setting the PIXSET register (3Ah) to 0x66 will select the 18-bit RGB pixel format. Really the only bits you are concerned with in this register are RIM and DPI[2:0], as DBI[2:0] will be ignored in RGB mode. See Page 134 of the ILI9341 datasheet for information on this register.

You can also reference Section 7.2.1 for information on RGB interface selection.

The maximum DOTCLK frequency for 18-bit RGB interface mode is 10Mhz. You can find more detail on timing characteristics and maximum values on Page 239 of the ILI9341 datasheet. 

Here is the example drive code for a Microchip PIC microcontroller for SPI and Parallel for the ILI9341, but they are pretty generic.