Supported external SDRAM (MT48LC4M32B2B5-6AIT:L) on STM32H745I-DISCO dev board.
Though MT48LC4M32B2B5-6AIT:L SDRAM itself provides 32-bit data bus, STM32H745I-DISCO board
routes only DQ[15:0] bits. Thus only half of the memory can be accessed: the accessible memory
configuration is only 1 Meg x 16 x 4 banks instead of 1 Meg x 32 x 4 banks.
Thus the accessible memory size is 8 MBytes.
Testing:
nsh> ramtest -a 0xD0000000 -s 8388608
RAMTest: Marching ones: d0000000 8388608
RAMTest: Marching zeroes: d0000000 8388608
RAMTest: Pattern test: d0000000 8388608 55555555 aaaaaaaa
RAMTest: Pattern test: d0000000 8388608 66666666 99999999
RAMTest: Pattern test: d0000000 8388608 33333333 cccccccc
RAMTest: Address-in-address test: d0000000 8388608
nsh>
