LTDC support

[b1aze]

Hi i am working with LTDC with STM32F429ZI Discovery -1 board with onboard LCD. I really want to drive a external LCD RGB display without An ic controller by utilising the Internal LTDC hardware inside the MCU . Can you please give some support on this

[MM..1]

Yes doit.

[Tesla DeLorean]

What kind of support? It's basically a circular DMA of the frame buffer which would come out of the SDRAM. It outputs the the R G B parallel pin, so you'd have to remove the display and wire your own up.

Resolution up to about 1.3Mpixel

You just have to set the clocking and horizontal/ vertical line timings.

[b1aze]

my RGB display does not have a buck boost converter nor a controller iC , so to give power i am using DC adapter with 12 v to enable backlight , and for data and clock i am using LTDC hardware in 16 bit mode. connections are made with jumber cables from my dev board to LCD , and when i turn it on   i am getting a black screen , and when i power off it turns white so that means LTDC may be working .  but i also have a framebuffer stored in external ram and that address is passed to LTDC so i should see some colors on the display but right now i am only seeing black screen.

LTDC timing and clock frequency are configured using this datasheet of my display .

  

 also dma is too configured for this 

but no matter what i do i am getting black screen , 

please tell me if it is a connection issue(i triple checked it), or grounding issue (because when i touch the display casing and touch the floor the display kinda flickers) , or framebuffer is  not  being stored in external ram or LTDC is not reading from external RAM.

[MM..1]

DMA2D is here irelevant. Primary condition is external RAM is ok working. Better is make first testing in internal RAM. Use layer 0 windows 100x100 px and create framebuffer in internal ram... Set background colors not black for testing. Show here your layer config. For example RGB565 require setup right alpha nums.

[b1aze]

now i changed to 100x100 resolution to match the internal RAM 

   buffer start adddress set to internal RAM address also changed the alpha constant to 255 still not working

edit : probably issue with the external RAM , i tried with some GDB and with some breakpoints , if i store the framebuffer in external ram i get hardfault_hadler , if i change to internal ram gdb is running okay , so i think issue is with external RAM.

[James_Walker]

Hi! Yes, the STM32F429ZI has an internal LTDC (LCD-TFT Display Controller) that can directly drive an external RGB interface display — you don’t necessarily need an external display controller IC, as long as your LCD supports parallel RGB signals