" When I configure my stm32 as slave and send one"This is not how SPI works. The slave cannot send on its own. It is always the master who initiates a data transfer (which better should be described as a data exchange. At the same time 1 byte is cloc...

The datasheet is your friend.SRAM2 is a 32kByte memory area which can retain its content even if you send the processor into standby mode (with extremly low power consumption).When powering up you want to make sure that the memory has not changed to ...