The data sheet says there is no FMC on STM32F446RE. Is that means there is no chance to connect external RAM with STM32F446RE?
While the datasheet indeed says that, it's more that you simply don't have enough FMC-connected pins on the 64-pin package to make any reasonable connection.
You still can connect a SRAM and simply manually "bit-bang" the read and write signals. Performance of course will be slow. SDRAM might be possible with a serious amount of hacking, but not practical at all.
There are also serially-connectible (SPI) SRAMs, e.g. from Microchip and ONSemi; again there is surely a need for some programming and some performance loss.
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