Zynq-7000 AP SoC and 7 Series FPGAs MIS v4.1
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UG586 November 30, 2016
Chapter 3:
RLDRAM II and RLDRAM 3 Memory Interface Solutions
RLDRAM II
In a typical RLDRAM II data bank configuration, 9 of these 10 I/Os are used for the data (DQ)
and one can be used for the data mask (DM). DM must be placed in the same byte lane as
the corresponding data; if two bytes share the same DM then it should be placed with one
of those bytes. The write clocks (DK/DK#) use one of the DQS pairs inside the data bank.
QK/QK# clocks must be placed on MRCC pins in a given data bank or in the bank above or
below the data. Xilinx 7 series FPGAs have dedicated clock routing for high-speed
synchronization that is routed vertically within the I/O banks. Thus, RLDRAM II interfaces
must be arranged in the banks vertically and not horizontally. In addition, the maximum
height is three banks.
After a core is generated through the MIG tool, the most optimal pinout has been selected
for the design. Manual changes through the XDC are not recommended. However, if the
XDC needs to be altered, these rules must be taken into consideration:
• The CK/CK# clocks must be placed in an address/control byte lane. The CK/CK# clocks
also need to be placed on a DQS pin pair. CK must be placed on the P location, and CK#
must be placed on the N location.
• The DK/DK# clocks must be placed in a data byte lane. The DK/DK# clocks also need to
be placed on a DQS pin pair. DK must be placed on the P location, and DK# must be
placed on the N location.
• Data (DQ) is placed such that all signals corresponding to 1-byte (nine bits) are placed
inside a byte group. DQ must not be placed on the DQS N location in a byte lane,
because this location is used for the 3-state control.
• Data Mask (DM) must be placed with one of the corresponding data byte lanes it is
associated with.
Note:
If DM pins are not used, they should be tied to ground. For more information, consult the
memory vendor data sheet.
• Xilinx recommends keeping all of the data generated from a single memory component
within a bank.
• Read clocks (QK and QK#) need to be placed on the MRCC pins that are available in
each bank, respectively. Data must be in the same bank as the associated QK/QK#, or in
the bank above or below.
• Address/control signals can be placed in byte groups that are not used for data and all
should be placed in the same bank. The address/control must be in the middle I/O
bank of the interfaces that span three I/O banks. Also, all address/control signals must
be in the same I/O bank. Address/control cannot be split between banks.
• For a given byte lane, the DQS_N location is used to generate the 3-state control signal.
The 3-state can share the location with DK# or DM only data.