vivado-constraints

name	vivado-constraints
version	1.0.0
description	Author and audit Vivado XDC constraint files. Use when creating constraints, finding unconstrained paths, debugging timing exceptions, checking clock definitions, or auditing I/O delays for completeness.
metadata	{"openclaw":{"requires":{"bins":["vivado"]},"emoji":"📐"}}

Vivado Constraints Runbook

1. Constraint Audit

check_timing -override_defaults {
  no_clock no_input_delay no_output_delay
  multiple_clock unconstrained_internal_endpoints
} -file /tmp/vivaclaw_rpt/check_timing.rpt

report_exceptions -coverage -ignored -file /tmp/vivaclaw_rpt/exceptions.rpt

2. Clock Definitions

• Primary: create_clock -period 10.0 -name sys_clk [get_ports sys_clk]
• Generated: create_generated_clock -name clk_div2 -source [get_pins mmcm/CLKIN1] -divide_by 2 [get_pins mmcm/CLKOUT0]

3. I/O Delays

• Input: set_input_delay -clock <clk> -max <val> [get_ports <in>]
• Output: set_output_delay -clock <clk> -max <val> [get_ports <out>]
• Use -min for hold/setup-min checks.

4. XDC Ordering Rules

1. Primary Clocks
2. Generated Clocks
3. Clock Groups / CDC
4. Timing Exceptions (set_false_path, set_multicycle_path)
5. I/O Constraints
6. Physical / Location Constraints (LOC, PACKAGE_PIN)

5. Finding Unconstrained Pins

set unconstrained [get_pins -hierarchical -filter {IS_CLOCK == 1 && CLK_OUT_PROPAGATION == ""}]
foreach pin $unconstrained { puts "MISSING CLOCK: $pin" }