what do i have to change to use the LTDC DPI (RGB888) instead of the build in DSI of the STM32f769I-Evalboard

Question

Hello

i just started a project with the STM32F769i-Evalboard with a 7" display with an DPI Interface.

My IDE is Atollic TRUESTUDIO with the STMCubeMX-Plugin. My Project is Build with the Atollic ARM Tools and a GNU Make Builder.

The basic programm with the initialisation of the device is done by that. I checked the Display working ( Framebuffer located in SDRAM ) with a Bitmap converted to C with the lcd-image-converter, so the LTDC from the STM32F7 is working properly.

Now is the Step to integrate the Embedded Wizard (EW) Project. To check the integration i made an Empty Project with only Displaying the image i converted before.

I added both libraries, the full folders, from the stm32f7 platform package (RTE and GFX). I was following the steps described in the documentation for the main loop (https://doc.embedded-wizard.de/main-loop?v=8.20). Now i m wondering what is missing to get the EM project running. The initialisation of the GraphicsEngine/RuntimeEngine needs some kind of Framebuffer.

quote : YourFramebuffer framebuffer;

What kind of Information is this YourFrameBuffer? Ans is that enough to get EW working?

And if i try to Build ( with YourFrameBuffer as a pointer to the Framebuffer memory ) there are lots of undefined references:

• EwFree
• EwPrint
• __vmt_GraphicsCanvas
• CoreRoot__Initialize
• CoreRoot__UpdateGE20
• EwAlloc
• EwApplicationClass
• EwFormat
• EwGetTicks
• EwMathPow
• EwMathRandInt32
• EwMove
• EwPanic
• EwScreenSize
• EwZero
• GraphicsCanvas__AttachBitmap
• GraphicsCanvas__DetachBitmap
• STM32BeginUpdate
• STM32BeginUpdateArea
• STM32BlendDriver
• STM32CopyDriver
• STM32CreateConstSurface
• STM32CreateSurface
• STM32DestroySurface
• STM32DoneViewport
• STM32EndUpdate
• STM32FillDriver
• STM32InitGfx
• STM32InitViewport
• STM32LockSurface
• STM32UnlockSurface

I think i m doing something really wrong here, but i thought the EW project (which should only display an image!) just needs a Framebuffer for working.
Or maybe there is a completely different way of getting the LTDC DPI working together with Embedded Wizard on the STM32F769I-Evalboard.

I'd be thankfull for any Hints.
Simon

Answer 1

Hello Simon,

the mentioned linker errors (undefined references) are caused by missing files. I assume that the files ewextgfx.c, ewextrte.c and the generated code of your UI test project are missing.

Nevertheless, it seems to me, that you are doing a lot of work that is already done...

Maybe the best starting point is the usage of the ready-to-use Build Environment for STM32F769 Evalboard. Please try to get this up and running with the unmodified Evalboard including the DSI display. Once this is successful, you can change the display and adapt just the display driver, that is located within the file ew_bsp_display.c.

What do you think about this approach?

Best regards,

Manfred Schweyer.

Comments

Hello Mr. Manfred,

I can run embedded project on STM32F769i-eval board. But we design new board. In our board we use LTDC DPI (RGB888) port for driving display. Is there any example project which use LTDC DPI (RGB888) port without Freertos. Our development environment is SW4STM32.

---

Hello Simon,

maybe the easiest way to do that is the following: Download the Build Environment for STM32F746 Discovery which contains a display initialization and access using LTDC without DSI. Then put this display related code (/TargetSpecific/ew_bsp_display.c) into your Build Environment for STM32F769 Evalboard and adapt the timing and initialization according your LCD.

Hope this helps...

Best regards,

Manfred.