AM335X: SPI configuration for LCD

Luke Marvin

I am attempting to use a higher resolution (800x480) lcd panel with the AM335x Starter Kit. This new LCD requires some configuration over SPI. I would like to know the best way to do this. I am using the latest Rowboat build of Android.

I have made an adapter board that connects all of the display pins on J1 and the SPI pins on J11 (the zigbee header) to the new display.

From my understanding I now need to do the following:

Edit the "NHD-4.3-ATXI#-T-1" panel in /kernel/drivers/video/da8xx-fb.c with the correct timing/resolution values.
Set the pinmux for the SPI pins on J11 and configure spidev. (Referring to this post. http://e2e.ti.com/support/arm/sitara_arm/f/791/t/218851.aspx)
Set the control registers on the LCD over the SPI

Does that sound reasonable? Is there a specific place I should stick the SPI writes?

over 12 years ago

0 Biser Gatchev-XID over 11 years ago

TI__Guru**** 393215 points

Hi Luke,

Yes, J11 is the correct place to connect SPI from the Starter Kit. Just keep in mind that the signal levels are 3.3V on the AM335X side, so if your display has a different I/O voltage you will probably need a level translator.

0 Jesper Taxboel over 11 years ago in reply to Biser Gatchev-XID

Intellectual 270 points

Would that allow you to use the graphics pipeline to write to the display, or do you need to do custom SPI communication to do any sort of graphics?

Kind regards

Jesper

0 Biser Gatchev-XID over 11 years ago in reply to Jesper Taxboel

TI__Guru**** 393215 points

We were discussing an LCD where the SPI interface used for configuration of the LCD only. I don't see how you will be able to transmit the framebuffer over SPI.

0 lofna kumari over 8 years ago in reply to Biser Gatchev-XID

Expert 2785 points

Hi,
i am also the same 4in lcd is going to interface with am335x using spi and rgb interface. using spi you need to set the registers to select the RGB mode. Right now the lcd we are using is direct rgb parallel. now i would like to use the spi based lcd with the same features like 800x480 pixel with other timings.

Is there any driver is available for spi LCD (controller inside the lcd is:ILI9806 ) using frame buffer logic.
rgds,

0 Manisha Agrawal over 7 years ago in reply to lofna kumari

TI__Mastermind 22946 points

There's no driver available for spi LCD. Which kernel version are you using? If you are using old fbdev driver, then modifying drivers/video/da8xx-fb.c to do the work is ok. If, on the other hand, you are using DRM, then you should do the mods in drivers/gpu/drm/tilcdc/tilcdc_panel.c.

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AM335X: SPI configuration for LCD