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
Design Guidelines
Design Rules
Memory types, memory parts, and data widths are restricted based on the selected FPGA,
FPGA speed grade, and the design frequency. The final frequency ranges are subject to
characterization results.
For general PCB routing guidelines, see
Appendix A, General Memory Routing Guidelines
.
Bank Sharing Among Controllers
No unused part of a bank used in a memory interface is permitted to be shared with
another memory interface. The dedicated logic that controls all the FIFOs and phasers in a
bank is designed to only operate with a single memory interface and cannot be shared with
other memory interfaces. With the exception of the shared address and control in the dual
controller supported in MIG.
Trace Length Requirements
The trace lengths described here are for high-speed operation and can be relaxed
depending on the application target bandwidth requirements. The package delay should be
included when determining the effective trace length. Note that different parts in the same
package have different internal package skew values. De-rate the minimum period
appropriately in the
MIG Controller Options
page when different parts in the same
package are used.
One method for determining the delay is to use the L and C values for each pin from the IBIS
models. The delay value is determined as the square root of (L × C).
Another method is to generate the package lengths using Vivado Design Suite. The
following commands generate a
csv
file that contains the package delay values for every
pin of the device under consideration.
link_design -part <part_number>
write_csv <file_name>
For example, to obtain the package delay information for the 7 series FPGA
XC7K160T-FF676, this command should be issued:
link_design -part xc7k160tfbg676
write_csv flight_time