1. May 20, 2010 Meeting David W. Smith
VHPI-AMS Subcommitte
May 20, 2010 Meeting
David W. Smith

2. Agenda Call to order Volunteer for minutes Approval of agenda
Review and approve minutes from April 22 meeting
Review action items and any content provided from them
Discussion
Next Meeting
AOB
Adjourn

3. VHDL-AMS VHPI Scope David W. Smith 19 May 2010
Note: Many of these ideas are derived from the ISCAS 2004 paper “Programming Interface Requirements for an AMS Simulator” by Martin Vlach as well as review of the LRM.

4. Possible Tools Tools which traverse the elaborated design
Examples: checkers, connectivity or behavior extractors, browser, schematic/symbol generators, parameter selection in setting up simulation, static power estimation
These do not interact with simulation but uses the design information defined in the model
Tools which query the elaborated design during simulation
Examples: profilers and coverage tools, dynamic power estimation
These interact with the elaborated design while simulation progress and does not control the simulation
Tools which control simulation and modification of the elaborated design
Examples: optimization, sensitivity, large signal steady state, worst case, parametric and statistical sweeps, fault insertion, debuggers, dynamic testbenches
These query and modify the elaborated design and also control the running of simulation.

5. Possible Tools (continued)
Tools which interact with simulation results and the elaborated design
Examples: results browsers, stress or safe operating region analysis, fault analysis
These browse both the simulation results and the elaborated design
Tools which couple the elaborated design and simulation cycle with other tools
Examples: coupled simulation, hardware in the loop
These provide a programmatic interface between architectures in the VHDL-AMS design and a “model” in the other tool and also provide hooks to synchronize the simulation cycle with the other tool (typically during event handling).
Definition of models written in procedural languages that are coupled to the elaborated design
Examples: C language models, embedded software models
These require the ability to interact with elaboration and become part of the elaborated design. Any interaction with the simulation cycle is the same as that available in VHDL-AMS.

6. Derived Requirements
Standard utilities provided in VHPI extended for VHDL-AMS objects. Examples include printing, comparing values, error handling.
Static design data provided in VHPI extended for VHDL-AMS objects.
Object access to query new objects such as free quantities and through/across quantities on branches.
Modification of generics on elaborated design, modifying connections, or adding/deleting elements.
This will require either incremental or full elaboration.
It does not really change the simulation cycle. It could be implemented as modifications on the elaborated design before simulation.
Modification of quantities during simulation (forcing quantity values, shorting and opening nodes) and adding/deleting elements
These requires modification to the simulation cycle to allow for breaking the simulation cycle, elaboration changes, and then continue the simulation cycle.
Extend VHPI foreign interface to support VHDL-AMS objects.
This will require standardization of the interface and abstraction of the simulation routines.
Simulation interaction and control
since VHDL-AMS does not define a simulation command this is somewhat problematic and can be very implementation dependent.
Simulation for VHDL-AMS is not just time domain. Extensions for Frequency and DC are required.

7. IEEE 1076-2008 VHPI Based off of IEEE 1076-2002 (so is not complete).
Provides
Library Information Model (library contents)
Design Hiearchy Information Model (elaborated design)
Includes callbacks during tool execution, model simulation, change of value of VHDL objects
Hierarchy, static object, connectivity, post-analysis data access
Support for implementing foreign models
Debug runtime
Dynamic elaboration
Support for stop/restart

8. Scope of VHPI-AMS effort
The VHPI-AMS is an extension of the VHPI defined in IEEE
The VHPI-AMS will not extend the digital information model to IEEE
Derived requirements that will be supported:
Standard utilities provided in VHPI extended for VHDL-AMS objects. Examples include printing, comparing values, error handling.
Static design data provided in VHPI extended for VHDL-AMS objects.
Object access to query new objects such as free quantities and through/across quantities on branches.
Modification of generics on elaborated design (which may cause the a re-elaboration) during restart.
Extend VHPI foreign interface to support VHDL-AMS objects.
Simulation interaction and control for stop/start
Derived requirements that will not be supported:
Modifications of the value of a quantity will not be supported in this version.
Adding/deleting elaborated items will not be support in this version.
Modifying connections, or adding/deleting elements on elaborated design.
Modification of quantities during simulation (forcing quantity values, shorting and opening nodes) and adding/deleting elements.
No special semantics for meta simulation (monte carlo, worst case, etc…) will be added. These may still be implementable with the core VHPI and above extensions.
These restrictions will allow most of the tools to be implemented