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Altera_Forum
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15 years ago

DDR3 Mirroring

Hi - I am trying to demystify the "mirroring" setting in the DDR3 controller. I am using a stratix iv device to implenet a Dual Rank 4GB by 4 RDIMM from Hynix. One of the parameters I have not been a...
Altera_Forum's avatar
Altera_Forum
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15 years ago

Usually the 2nd rank of a DIMM would be mirrored, so for:

1. Controller for 1 DIMM of dual rank configuration:

Mirror Addressing Option in the Uniphy Megafunction GUI would be set to a value of 10 (Rank1 - Rank0)

2. Controller for 2 DIMMs of dual rank configuration:

Mirror Addressing Option in the Uniphy Megafunction GUI would be set to a value of 1010 (DIMM1,Rank1 - DIMM1,Rank0 - DIMM0,Rank1 - DIMM0,Rank0)

As I understand it, the purpose for address mirroring is that the DRAM ICs on the back of the DIMM module are mirrored from the ICs on the front. Rather than the memory module provider having to criss cross all of the address lines on the PCB for the back side DRAM ICs, the controller will do the address swapping in the FPGA when writing to the back side DRAM ICs.