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8-bit TFT using SDMA and EMI [Yocto build]

Question asked by Jasper Nuytten on Mar 13, 2017
Latest reply on Jun 20, 2017 by shree97

Hi all,


I have a small 8-bit interface TFT display and a SOM with an IMX6UL processor running a Yocto distribution.
I want to drive this display but I cannot seem to find the solution. The display only has 8-bit data channel and some control lines (reset, chip select, ...). No address lines!


I have connected the display using GPIO and configured notro's fbtft driver (GitHub - notro/fbtft: Linux Framebuffer drivers for small TFT LCD display modules ). I succeeded in getting an image on the screen, however the refresh rate was too low. I then changed the driver a little just to make it toggle a GPIO and it seems that they're not able to toggle fast enough to get a decent refresh rate.


Now I'm thinking about driving this display using the SDMA and EMI/EIM modules of the iMX6UL chip. As far as I understand, DMA is used to transfer data from place A to place B without CPU intervention and that EMI/EIM bus is used to access external memory. The display controller has its own memory, so I would suggest that this is possible? But I have no idea how, can somebody push me a little in the right direction?

If SDMA and EMI are not the solution, can somebody please explain me what they're used for then?


If more information is needed to give a good answer please ask, I really want to understand these concepts.
Kind regards



TFT DISPLAY + CONTROLLER: RK020JH100 - ILI9335 (very similar to ILI9325)
SOM with iMX6UL processor