iabdalkader b603066bc2 stm32/sdram: Add SDRAM enter/leave self-refresh mode functions.
These functions enable SDRAM data retention in stop mode.  Example usage,
in mpconfigboard.h:

    #define MICROPY_BOARD_ENTER_STOP sdram_enter_low_power();
    #define MICROPY_BOARD_LEAVE_STOP sdram_leave_low_power();
2020-12-17 23:19:25 +11:00
..