When the EXT shim and external memory system are present, the SPI bus timing budget must be analyzed to ensure a robust implementation. The result of the analysis confirms that the external memory system is functional, and reveal any constraints it might pose on the maximum frequency of the system-level design example input clock.
Example Conclusion
Using the example data from the AMD Vivado™ Design Suite timing report for an AMD Kintex™ 7 SEM IP implementation, the memory interface is functional. The most stringent requirement on Tclk is that Tclk ≥ 14.512 ns, as the memory interface only works when the input clock frequency is 68.908 MHz or lower. Other input clock frequency limits, such as the internal configuration access port (ICAP) maximum clock frequency and the system-level example maximum clock frequency, must also be considered.