Moving LTDC pins on DK2 board?

[AJaro.2]

Just wondering if I can edit the pinctrl.dsi file to change the pins to the Raspberry Pi header, rather than the HDMI encoder, so I can try DPI Raspberry Pi displays.

In CubeMX the LTDC and most of the peripherals are locked, just wondering if it is necessary to configure them there or if a device tree configuration is enough.

Thanks

[Olivier GALLIEN]

Hi @AJaro.2​ 

Could you please give the exact reference of the screen you want to use ?

Is it this one ?

https://www.raspberrypi.org/products/raspberry-pi-touch-display/

Thanks

Olivier

[AJaro.2]

Hi Oliver,

No, even more basic than that--something like this: https://www.waveshare.com/product/mini-pc/raspberry-pi/displays/others/5inch-lcd-for-pi.htm

Here are some more Pi-specific details: http://blog.reasonablycorrect.com/raw-dpi-raspberry-pi/

But it's essentially just driving the LCD directly, as opposed to through an interface like DSI. The DK2 board is already configured to do this with LTDC, but it's used to for the HDMI bridge. My question is can I simply remap the pins to the Pi header instead.

Thank you!

[Olivier GALLIEN]

Hi @AJaro.2​ 

Did you secure everything at hardware level ?

Pin signal level are compatible ?

Did you find how to get power and back light control signal ?

From software point of view you will have to create a new node for you screen in the DT to enable it.

What do you mean by "In CubeMX the LTDC and most of the peripherals are locked" ?

Olivier

[AJaro.2]

Hey Oliver, thanks for the response. I simply mean that STM32CubeMX says "Warning: STM32CubeMX does not support the configuration of this peripheral. However, this IP can be configured manually."

So my question is more how to actually do it manually.

[Olivier GALLIEN]

Hi @AJaro.2​ 

You can note this message is present when peripheral is allocated to A7 context.

Configuration is then manage on Linux side and has to be handle "manually" by completion of the generated Device Tree under dedicated USER SECTION.

You can find on user guide https://wiki.st.com/stm32mpu some guideline for Device Tree configuration for most of peripherals.

In your case i guess https://wiki.st.com/stm32mpu/wiki/LTDC_device_tree_configuration might be of some help

Olivier