Games / Command flash cards / Liberty timing libraries

Liberty timing libraries read against a real library

Choose a section to drill, or play every section mixed together. Each section lists the commands it covers, and any kinds of card it holds besides the plain one: a command whose meaning you pick.

SourceLiberty is the format that carries a cell library's timing and power. These cards are checked against the Nangate45 library that OpenROAD-flow-scripts ships, and the excerpts are quoted from it. Liberty is a Synopsys format whose specification is licensed; the behaviour described here is what the open timer OpenSTA implements, and answers link to its command reference. Reference: the OpenSTA command reference (Liberty on GitHub).

All sections

A mixed round drawn from every section. Due cards come first, then new cards in random order.

53cards across 8 sections
mixed round play

Library header

The units, the delay model, and the conditions a library was characterized at.

time_unitcapacitive_load_unitdelay_modelnom_voltageoperating_conditionsdefault_max_transition
9 cards play

Cell and pin groups

What a cell declares about itself, and what each pin declares.

cellareaffpg_pinpindirectioncapacitancefunction
7 cards play

Special cells

Latches, tristate outputs, clock gates, and scan flops declare themselves differently.

latchpresetclearthree_statestatetableclock_gating_integrated_celltest_cell
5 cards play

Timing arcs

The arcs between pins: what relates them, what kind of check or delay each is.

timingrelated_pintiming_typetiming_sensewhensdf_cond
7 cards play

Delay tables and models

How a delay is stored, looked up, and which model a library uses.

cell_risecell_fallrise_transitionindex_1index_2lu_table_template
7 cards play

Constraints and limits

Setup, hold, and the electrical limits a cell declares.

setup_risinghold_risingrecovery_risingremoval_risingmax_transitionmax_capacitancemax_fanout
6 cards play

Power

Leakage by state, and the energy a switching cell spends internally.

cell_leakage_powerleakage_powerinternal_powerrise_powerrelated_pg_pin
5 cards play

Reading a library

Questions about a real Liberty file, quoted from Nangate45.

cellpintimingleakage_power
read the output
7 cards play