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Hi !
I join the question! I am also very interested in the possibility of using external SRAM/SRAM memory on STM32 controllers of the F405,427,429 series, running Espruino.
I think @MarkBloom is mistaken about the possibility to apply QSPI memory on the F405 F407 series, as far as I know there is only the possibility to apply parallel PSRAM/SRAM memory. I am also very interested in the possibility of expanding FLASH memory by connecting it via the parallel interface of the FSMC memory controller? Are you interested in the possibility of simultaneous operation of PSRAM and FLASH in Espruino? Will the execution environment see PSRAM and FLASH? Will the files on this extended memory be visible from the Espruino Web IDE?
As for @fanoush's comment, I suppose this is a special case, I also met many successful C++ projects on the STM32 series below STM32H7, which is discussed in the article 'Why you should fall in love with the RP2350' from @Dmitry.GR .
The STM32H7 crystals are significantly more complex than the F4xx series.
@Gordon please comment on the question!
Hi,
Espruino works off a fixed size memory area, and the default build just uses what's in the bare chip.
You'd have to make your own build that enabled PSRAM/ext flash/etc, and then yes, you could relocate vars into that (assuming it was memory mapped?).
Writing to external flash might be more of an issue, I think you may have to implement that yourself in jshardware.c if the standard STM32 flash write functions won't do it.
... but it's definitely possible to do, just not with a plain build