Controlling Enable/Reset Extraction with Synthesis Attributes - 2021.2 English

UltraFast Design Methodology Guide for Xilinx FPGAs and SoCs

Document ID
UG949
Release Date
2021-11-19
Version
2021.2 English

You can force control set mapping by applying the DIRECT_RESET / DIRECT_ENABLE / EXTRACT_RESET / EXTRACT_ENABLE attributes as needed to handle the mapping of control sets for a given structure.

When the design includes a synchronous reset/enable, synthesis creates a logic cone mapped through the CE/R/S pins when the load is equal to or above the threshold set by the -control_set_opt_threshold synthesis switch, or creates a logic cone that maps through the D pin if below the threshold. The default thresholds are:

  • 7 series devices: 4
  • UltraScale devices: 2