Hi,
I have recently managed to get the EMIF on a C5515 device interfaced and working with an external mobile SDRAM, but have noticed the actual working memory block size works out to be 0x3B0000 instead of the 0x400000 as I thought originally. Memory testing beyond the address 0x400000 returns an error (for address bus testing) ...
In SPRS660A on page 20 it shows the memory map for external SDRAM to be in total from 0x50000 to 0x800000 = 8M minus 320K Bytes SDRAM/mSDRAM memory block. I actually seem to get more like a 4M minus 320K bytes (a DSP byte being taken as 16-bits in this case). The actual memory is capable of supplying the full 1M x 16-bit x 4 banks = 64Mbits of SDRAM (being 4Mbytes of SDRAM) so where is the 320Kbytes gone then ?
Only the CS0 line is used to activate the external mSDRAM, so I thought when accessing memory starting at 0x50000 I should be accessing the full 0x400000 bytes all the way to 0x450000, but this does not appear to be the case., as my addressing tests return errors exactly at 0x400000.
Could somebody explain the minus 320Kbytes to me please ? To access another 4Mbytes do I need to add another mSDRAM chip and use CS1 to access it to get 8Mbytes minus 320Kbytes?
Thanks in advance and regards,
MM
