If you haven't read the CAD tool information page, READ THAT FIRST.

Nanosim is a fast event-driven circuit simulation engine.  It differs from HSPICE in that the circuit is partitioned into a set of stages, usually defined by transistor connected together by their sources and drains (referred to as channel-connected components, CCCs, or channel-connected regions, CCRs).  On when the inputs of the CCC change is the circuit simulation engine envoked on that CCC.  In addition, Nanosim uses simplified device models to speed analysis.

Nanosim work very well on digital designs.  For mixed-signal designs, you must use care in how the design is partitioned and the accuracy options you use to get good results on the analog pieces.  This will be true for SRAM sense amps, for example, or any PLL or DLL designs.

You will use Nanosim for functional verification; that is, to run large number of patterns through your design to make sure that your design is logically correct.  You may also use Nanosim for timing verification, although it is always a good idea, given the approximate nature of the device models, to simulate at least a few patterns in HSPICE.  You will find, however, that Nanosim is dramatically faster than HSPICE on large designs.

Nanosim is largely run outside of the Cadence environment.  It is a Synopsys tool; consequently, neither Synopsys nor Cadence has a particular interest in getting a good Cadence integration..  To run Nanosim on your design, you'll need to perform the following steps:

• Create a run directory in which you will invoke Nanosim, for example, ~/nanosim.
• From the schematic you wish to simulate, create an HSPICE netlist.  To do this, bring up the Analog Artist window (by invoking Tools -> Analog Environment from the schematic window).   From the Analog Artist Window, choose your analysis options with Analyses->Choose as you would normally for an HSPICE run.  Then choose, Simulation -> Netlist -> Create Final.  When the design finishes netlisting, a view screen with open with the final HSPICE netlist.  Save this to a file in your Nanosim run directory with the Save As option.  For example, let's save it as the file ~/nanosim/design.spi.
• Now cd to your Nanosim run directory.  Create a file called "config.cfg."  In this file, put the single line:
  print_node_voltage *
  This will be used to tell Nanosim to save the voltage on all of the nodes of your circuit for viewing in the waveform tool.
• To run Nanosim, at the UNIX command line type:
  nanosim -n design.spi -c config.cfg
• When the run completes, you can view the results by typing:
  wd nanosim.out
  which opens up the waveform display tool.   To add signals for display, choose Edit->Add Signals.  Select and drag the signals you want to display from the list window into the waveform window.

type vec
signal reset_inst start_inst
radix 1 1

0 1 0
10 0 0
5100 0 1

Another larger stimulus example is given here.

This file, stored for example as the file "stimulus", can be used to set the values of the signals reset_inst and start_inst.  The first column is the time (in nanoseconds) and the second and third columns are the logic values.  With the vector file, Nanosim must be invoked with the command:
nanosim -n design.spi -nvec stimulus -c config.cfg