A.5.1. Legacy pad interface

Table A.15 shows the legacy pad interface signals.

Table A.15. Legacy pad interface signals

  SignalType

Source or

destination

Description
 Signals for a DDR2 DMC, with or without ECC support:
 add[15:0]OutputExternal memoryAddress
 apOutputExternal memoryAuto precharge
 ba[MEMORY_BANK_WIDTH-1:0][a]OutputExternal memoryBank select
 cas_nOutputExternal memoryColumn address strobe
 ckeOutputExternal memoryClock enable
 clk_out[MEMORY_CHIPS-1:0][b]OutputExternal memoryMemory clock
 cs_n[MEMORY_CHIPS-1:0]OutputExternal memoryChip select
 data_enOutputExternal memoryData direction enable
 dqm[MEMORY_BYTES-1:0][c]OutputExternal memoryData bus mask
 dqs_in_<n>InputExternal memoryData strobe in
 dqs_in_n_<n>InputExternal memoryData strobe in bar
 dqs_out_<n>OutputExternal memoryData strobe out
 odt[MEMORY_CHIPS-1:0]OutputExternal memoryMemory IO termination control
 odt_readOutputOutput pad IODevice IO termination control
 ras_nOutputExternal memoryRow address strobe
 we_nOutputExternal memoryWrite enable
 Signals for a DDR2 DMC without ECC support:
 dq_in[MEMWIDTH-1:0] [d]InputExternal memoryData bus in
 dq_out[MEMWIDTH-1:0] [d]OutputExternal memoryData bus out
 Signals for a DDR2 DMC with ECC support:
 dq_in[MEMWIDTH+ECCWIDTH-1:0] [e]InputExternal memoryData bus in
 dq_out[MEMWIDTH+ECCWIDTH-1:0] [e]OutputExternal memoryData bus out
 dqs_in_eccInputExternal memoryECC strobe in
 dqs_in_n_eccInputExternal memoryECC strobe in bar
 dqs_out_eccOutputExternal memoryECC strobe out

[a] The MEMORY_BANK_WIDTH value depends on the number of banks in the configuration.

[b] MEMORY_CHIPS is the number of chip selects and is set during configuration of the DDR2 DMC.

[c] MEMORY_BYTES is the width of the external memory data bus in bytes and is set during configuration of the DDR2 DMC.

[d] MEMWIDTH is the width of the external memory data bus in bits and is set during configuration of the DDR2 DMC.

[e] The value of ECCWIDTH depends on MEMWIDTH as follows:

      -  if MEMWIDTH = 16 then ECCWIDTH = 6

      -  if MEMWIDTH = 32 then ECCWIDTH = 7

      -  if MEMWIDTH = 64 then ECCWIDTH = 8.


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