What frame buffer is used on the STM32H735IG Discovery?

[Southbranch]

Hi!

Forgive me if this is a simple question:

This board comes with two OctoSPI:s of 512Mb and 128 Mb respectively, the latter is using HyperBus. Is the default config. setup using any of these memories as the display's frame buffer or is the internal RAM used?

If not, is it possible to use an OctoSPI as a frame buffer in general?

If yes, are there any drawbacks in terms of performance (e.g. max resolution) for using a OctpoSPI as frame buffer or any other consideration?

It would be great not having to route all the adress and data lines on a custom PCB using a OctoSPI as the frame buffer compared to using a parallel SDRAM

[Tesla DeLorean · Accepted solution]

>>Forgive me if this is a simple question

It is perhaps something you should be capable of determine for yourself.

Certainly something you'd want to test and do due-diligence on before committing to a PCB

The examples look to use either, grep sources for "LCD_FRAME_BUFFER", perhaps also "OSPI_RAM_WRITE_READ_ADDR"

0xD0000000 is the SDRAM Bank 2

0x70000000 is the OCTO SPI HyperRAM

You could measure the bandwidth available to the processor with some simple timed benchmarks.

Can you not estimate the bandwidths required to a) paint the static display, b) modify/manipulate the frame buffer?

If the resolution / colour depth of the display permits, the Internal SRAM will likely offer the highest bandwidth.

I'd expect SDRAM to have far higher availability, and choices

[Southbranch]

Many thanks for pointing me in the right direction!