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

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

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 1076-2008 LRM.

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.

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.

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.

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

Scope of VHPI-AMS effort The VHPI-AMS is an extension of the VHPI defined in IEEE 1076-2008. The VHPI-AMS will not extend the digital information model to IEEE 1076-2008. 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