Fonts in external SPI flash, along with other data (memory mapped flash vs. command mode flash)

[Tuoman]

I use TouchGFX and STM32H7 system. It needs large font files (chinese + many sizes) which will not fit into internal RAM.

I also need to write log data into flash. I would want to use the same flash to store fonts and store the logging data. But TouchGFX fonts require memory-mapped mode, and storing data requires command mode.

Which option is the best?

1. Use 1 physical flash (switch external flash mode between memory-mapped for fonts and command mode for storing data)
2. Use 2 physical flash chips, one with FW and fonts (memory-mapped mode), other for data only (command-mode)

I would use STM32H7B0 with 2 external flash option (FW+fonts in external mm-flash, data in external cmd-flash), STM32H7B3 with 1 external flash option (FW in internal flash, Fonts+data in external flash with mode switching between mm/cmd).

[Alexandre RENOUX · Accepted solution]

Hello,

I think both solutions are fine. I believe having 2 physical external flash is more expensive than 1 single external flash. However, you will avoid switching between two modes on a single Flash in this case.

Both are doable and if you choose only 1 physical external flash just set it in command mode only when you want to write. As soon as your write is finished, switch back to memory mapped mode.

/Alexandre

[Tuoman]

Okay, thank you for clarification!