Flip-flop Phase Inverted
In power timing critical designs, Place and Route tool may change some flip-flops' phase by adding inverters in input pin and output pin.
Figure 1: Flip-flop Phase Inverted
API set_mapping_method('-phase') is used to handle these cases.
# GofCall ECO script, run_example_ff_phase_inverted.pl
use strict;
undo_eco;
# Discard previous ECO operations
setup_eco(
"eco_example");
# Setup ECO name
read_library(
"art.90nm.lib");
# Read in standard library
read_svf(
"-ref",
"reference.svf.txt");
# Optional, must be loaded before read_design, must be in text format
read_svf(
"-imp",
"implementation.svf.txt");
# Optional, must be loaded before read_design, must be in text format
read_design(
"-ref",
"reference.gv");
# Read in Reference Netlist
read_design(
"-imp",
"implementation.gv");
# Read in Implementation Netlist Which is under ECO
set_top(
"SOC_TOP");
# Set the top to the most top module SOC_TOP
set_mapping_method('-phase'); # Check flop phase during LEC
set_ignore_output(
"scan_out*");
set_pin_constant(
"scan_enable", 0);
set_pin_constant(
"scan_mode", 0);
fix_design;
save_session(
"current_eco_name");
# Save a session for future restoration
report_eco();
# ECO report
check_design(
"-eco");
# Check if the ECO causes any issue, like floating
write_verilog(
"eco_verilog.v");
# Write out ECO result in Verilog
exit;
# Exit when the ECO is done, comment it out to go to interactive mode when ’GOF >’ appears
Check Flip-flop Phase Inverted in user manual
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