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TheMightyDuckOfDoomTheMightyDuckOfDoom
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openroad: post-route antenna fixing
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‎openroad/scripts/chip.tcl‎

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@@ -25,6 +25,8 @@ source scripts/init_tech.tcl
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set log_id 0
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# Set number of threads for multithreaded operations
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set_thread_count 8
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###############################################################################
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# Initialization #
@@ -296,12 +298,14 @@ detailed_route -output_drc ${report_dir}/${log_id_str}_${proj_name}_route_drc.rp
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-clean_patches \
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-verbose 1
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# Post-route antenna fixing
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source scripts/post_route_antenna_fix.tcl
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utl::report "Saving detailed route"
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save_checkpoint ${log_id_str}_${proj_name}.drt
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report_metrics "${log_id_str}_${proj_name}.drt"
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report_image "${log_id_str}_${proj_name}.drt" true false false true
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###############################################################################
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# FINISHING #
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###############################################################################

‎openroad/scripts/post_route_antenna_fix.tcl‎

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@@ -0,0 +1,153 @@
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# Copyright 2025 ETH Zurich and University of Bologna.
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# Solderpad Hardware License, Version 0.51, see LICENSE for details.
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# SPDX-License-Identifier: SHL-0.51
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# Authors:
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# - Tobias Senti <tsenti@ethz.ch>
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## Post-Route Antenna Fix Script
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# This script checks for antenna violations after detailed routing
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# and attempts to fix them by adding antenna diodes to the affected pins.
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# Runs up to $max_iterations or until no violations are found anymore.
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# Maximum number of iterations until giving up
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set max_iterations 3
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# Counter for unique diode names
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if {![info exists ::antennacounter]} {
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set ::antennacounter 0
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}
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set early_exit 0
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for {set iteration 1} {$iteration <= $max_iterations} {incr iteration} {
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puts "\n\n=== Antenna Fix Iteration $iteration ==="
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set report_file_name "post_route_antenna_$iteration.rpt"
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puts "Check for antenna violations"
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check_antennas -report_file $report_dir/$report_file_name
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puts "Parsing antenna report"
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# Read in report
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set fp [open $report_dir/$report_file_name]
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set lines [split [read $fp] "\n"]
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close $fp
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# Parse report
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set net_name ""
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set pin_name ""
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set has_violation 0
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set pin_with_violations {}
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foreach line $lines {
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# Trim and split line
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set line [string trim $line]
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set split_parts [split $line]
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set parts {}
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foreach part $split_parts {
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if { $part ne "" } {
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lappend parts $part
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}
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}
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# Check if it is a net or pin
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set first_word [lindex $parts 0]
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if { $first_word eq "Net:" } {
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set net_name [lindex $parts 1]
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puts "Processing net: $net_name"
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}
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if { $first_word eq "Pin:" } {
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set pin_name [lindex $parts 1]
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set has_violation 0
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puts " Pin: $pin_name"
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}
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# Prevent multiple additions of the same pin
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if { $has_violation eq 0 } {
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# Check if it is a violation line
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set last_word [lindex $parts end]
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if { $last_word eq "(VIOLATED)" } {
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lappend pin_with_violations $pin_name
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set has_violation 1
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puts " Adding pin $pin_name to violation list"
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}
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}
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}
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puts "\n\n"
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# If no violations, exit loop
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if { [llength $pin_with_violations] eq 0 } {
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puts "No antenna violations detected, exiting."
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set early_exit 1
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break
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}
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# Add one antenna diode per pin with violation
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puts "Add antenna diodes"
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set block [ord::get_db_block]
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set ant_master [odb::dbDatabase_findMaster [ord::get_db] "sg13g2_antennanp"]
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set violation_nets {}
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foreach pin $pin_with_violations {
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puts "Pin with antenna violation: $pin"
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set parts [split $pin "/"]
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set pin_name [lindex $parts end]
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set cell_name [join [lrange $parts 0 end-1] "/"]
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# Get instance
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set inst [odb::dbBlock_findInst $block $cell_name]
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puts [odb::dbInst_getName $inst]
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# Get iterm (db representation of pin)
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set iterm [odb::dbInst_findITerm $inst $pin_name]
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# Get net connected to iterm
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set net [odb::dbITerm_getNet $iterm]
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set net_name [odb::dbNet_getName $net]
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# remove backslashes from net name
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set net_name [string map {"\\" ""} $net_name]
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lappend violation_nets $net_name
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# Remove routing of the net if it has any
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set wire [odb::dbNet_getWire $net]
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if { $wire ne "NULL"} {
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odb::dbWire_destroy $wire
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}
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# Create antenna diode instance
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set ant_name "post_route_ant_diode_[incr ::antennacounter]"
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set inst [odb::dbInst_create $block $ant_master $ant_name]
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# Connect antenna diode to the net
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set inst_iterm [odb::dbInst_findITerm $inst "A"]
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odb::dbITerm_connect $inst_iterm $net
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# Place antenna diode near the pin (gate to protect)
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set xy [odb::dbITerm_getAvgXY $iterm]
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puts "Placing antenna diode at $xy"
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odb::dbInst_setLocation $inst [lindex $xy 1] [lindex $xy 2]
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odb::dbInst_setPlacementStatus $inst "PLACED"
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}
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# Refine placement of diodes
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puts "Detailed placement"
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detailed_placement
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# Ensure diodes are connected to power
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puts "Connect power"
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global_connect
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# Reroute affected nets
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puts "Detailed route"
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detailed_route -output_drc ${report_dir}/${log_id_str}_${proj_name}_post_route_antenna_fix_drc.rpt \
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-droute_end_iter 30 \
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-drc_report_iter_step 5 \
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-save_guide_updates \
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-clean_patches \
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-verbose 1
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}
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# Final antenna check if we have not exited early i.e. fixed all violations
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if {$early_exit eq 0} {
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puts "Final antenna check"
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check_antennas -report_file $report_dir/$report_file_name
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}

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