Can I use PSRAM as FrameBuffer in STM32L4R9?

[JPark.14]

Dear TouchGFX team,

I am developing STM32L4R9 B/D including

• DSI video mode LCD.
• PSRAM
• OctoSPI Flash
• etc..

I use two frame buffer in internal SRAM and one animation storage buffer in PSRAM.

• setFrameBufferStartAddresses((void*)FRAME_BUFFER0, (void*)FRAME_BUFFER, (void*)ANIMATION_STORAGE);

== > It works fine without special problem.

Buf two frame buffer in internal SRAM is so big and I need to change the location to PSRAM.

So I changed the address of FRAME_BUFFER and FRAME_BUFFER0 to PSRAM address.

But the display is crashed. I can't get screens that I wanted. As I mentioned, no problem when I use PSRAM as animation storage buffer.

Using PSRAM as a frame buffer is impossible? OR It's just a problem in setup?

Please let me know if any solution or good guideline.

Thanks in advance!

J.Park

[MMoon.1]

Hey J.Park,

I think there an errata regarding PSRAM over OCTOSPI.

[JPark.14]

Hi, MMoon,

Thank you for your response about my question.

I use PSRAM as a normal buffer successfully. The only problem is when I use PSRAM as a frame buffer.

Where can I find it if there an errata about PSRAM? site URL or whatever... Could you more information about this matter?

Thanks in advance!

J.Park

​

[AME MCU Support Center BB]

Hi JPark,

Please refer to section 2.7.22 PSRAM not supported

https://www.st.com/resource/en/errata_sheet/dm00371862-stm32l4rxxx-and-stm32l4sxxx-device-errata-stmicroelectronics.pdf

With regards,

[JPark.14]

Hi,

Thank you for your reply. But still I have some question.

STM32L4R9 Discovery board include PSRAM and works well. Of course is connected through FMC.

My new board is the same structure as L4R9 Discovery board and PSRAM works well.

My question from my post is about how to use PSRAM as a frame buffer. Usage of PSRAM as a normal memory is no problem.

Could you check it again?

Thanks in advance.

J.Park

[waclawek.jan]

Maybe OP talks about PSRAM connected through FMC...

JW

[JPark.14]

Thanks, JW.

Based on your answers, I asked the question above again ..

Do you have any idea about the above matter?

Thanks in advance!

J.Park

[berendi]

What is the pixel clock of the display? It might be too fast for the PSRAM to handle. What data rate can it sustain?