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Eldo Control Language
Overview of the Eldo Control Language
Overview of the Eldo Control Language
The Eldo Control Language extends the raw capabilities of Eldo by adding support for
sequential operations, results-based decision taking, and the arbitrary formatting of simulation
results.
In its classical mode of operation, Eldo reads in a netlist that contains both the circuit element
description and a number of commands. The commands usually start with a “.”; for example
.TRAN, .STEP, .EXTRACT, and so on. The relative position of the commands is unimportant;
Eldo uses its own hard-coded internal logic to decide the sequence in which to execute the
commands, between which there is virtually no communication. Eldo also decides how to
format the results of the various commands it executes.
In many cases, the Eldo default logic is sufficient for a designer to achieve the required
simulation results. For situations where more custom control is required, the Eldo Control
Language enables a designer to bypass the hard-coded execution logic and formatting, and
implement whatever sequence of simulation commands is required, from very simple ones to
full algorithms. In addition, the formatting of the results can be freely defined.
The Eldo Control Language is based on two fundamental structures: testbenches and tasks.
• A testbench is a reusable parameterized block of simulator commands that can be
instantiated in the netlist to simulate. It is comparable to the notion of a macro from a
classical programming language, such as C, or comparable to #define in Eldo, when
using the -E/-EE command-line argument, see “Directives Interpreted using the C Pre-
Processor (-E/-EE Arguments)” on page 126.
• A task is a sequence of instructions that specifies which netlists are to be simulated and
what to do with their results. The netlists simulated by the tasks are typically created by
instantiating testbenches with different parameter values. Inside a task, conditions can
be tested, multiple simulations can be launched through for and while loops, their results
(typically the .EXTRACT/.MEAS and the waveforms) easily retrieved and tested for,
and output files printed in arbitrary formats. Any simulation plan exceeding the hardcoded
capabilities of Eldo can be implemented.
The power of the Eldo Control Language is that it is implemented directly within Eldo. This
means that the Eldo Control Language “knows” the syntax and semantics of analog simulation;
it knows what a simulation netlist is, and what .EXTRACT/.MEAS or waveforms are, and thus
can interface directly with these objects.
See also:
• “Testbenches” on page 809
• “Tasks” on page 814
Eldo Control Language Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 803
Eldo Control Language Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 806
802
Eldo® User's Manual, 15.3