Hello!
I have my custom board with STM32F767 and external SDRAM (MT48LC4M32B2 - 128MBit) on it.
Basically the connection between them works fine, because I'm able to write and to readout the data. The problem is, that if I try to access an address above the half of my external SDRAM, the the program crash...
Here is the connection between the MCU and SDRAM:
So I have used this as the starting address for my SDRAM. By this I shall have a maximum address space of 0xC000 0000 - 0xCFFF FFFF.
The connected SDRAM has 4 banks with 4096 rows x 256 columns x 32Bit cell width.
So one bank shall have 1.048.576 cells x 32Bit = 4.194.304Byte and so = 4.194.304 addresses.
This also means that one bank has an address space of 0x0040 0000 (4.194.304Byte) and the whole SDRAM shall have an address space of 0x100 0000 (4 x bank address space).
When I use the memory viewer during debugging, then I can see, that addresses only up to 0x0080 0000 are mapped:
This means, that only 2 banks are mapped. I have set the CubeMX for 4 internal banks, so I'm wondering what I did wrong?
Why the mapping is going only up to the 0xC080 0000?
Thank you for any help on that!
Regards,
Gregor
Update: I have discovered this site with some hints on how to solve this issue:
https://www.keil.com/support/docs/3777.htm
Basically 3 solutions are proposed:
1. Enable the MPU for this region
2. Remap the SDRAM to a different address
3. Generate code with the natural alignment
The 1. solution is to insert the specified code before any SDRAM activity. This doesn't solve my issue: the mapped adress ends at 0xC080 0000...
The 2. solution is to remap the memory to another region of the STM32F7: 0x6000 0000. This also dosen't help. Here the screen shot with my code redirected to 0x6000 0000:
The 3. solution is to use a natural aligment with special compiler option: --no_unaligned_access
This I haven't tried yet, because I don't know where to set this option in the CubeIDE...
