OctoSPI Flash in memory mapped mode also used for application data

[FlorianZuellig]

Hi,
We have a customer board with STM32H735 and OctoSPI flash in memory mapped mode.
Memory is used for TouchGfx elements and as external code memory.
Now we should add a simple file system for saving some data on the board.

Is it possible to use a file system (read/write access) on a OSPI flash in memory mapped mode.
Due to AN5050 and other resources i would say its not possible.

Can someone confirm to me if this is the case or if there is a way to solve this.

[KDJEM.1]

Hello @FlorianZuellig and welcome to the Community :),

For graphical applications, I advise you to use this ideal configuration where:
• An HyperFlash memory is connected to OCTOSPI2 that is used to store graphical primitives.
• An HyperRAM memory is connected to OCTOSPI1 that is used to build frame buffer.
• Both OCTOSPI1 and OCTOSPI2 must be configured in HyperBus Memory-mapped mode, with Multiplexed mode enabled.
• Any AHB master (such as CPU, LTDC, DMA2D or SDMMC1/2) can autonomously access to both memories, exactly like an internal memory.

Note that, if there is an on-going memory-mapped read (respectively write) operation, the application can start a write operation as soon as the on-going read (respectively write) operation is terminated.

Please take a look at these posts: Post1, Post2  and these examples OSPI_NOR_MemoryMapped_DTR,   OSPI_HyperRAM_MemoryMapped may help you.

Thank you.

Kaouthar

[LCE · Accepted solution]

Just working with H735-Discovery.

You are right, the flash canNOT operate in memory-mapped WRITE mode.

Which makes sense, due to the fact that you can only write a complete flash page (standard for all (?) flash ICs).