© 2005 Xilinx, Inc. All Rights Reserved This material exempt per Department of Commerce license exception TSU HDL Co-Simulation

This material exempt per Department of Commerce license exception TSU © 2005 Xilinx, Inc. All Rights Reserved

HDL Co-Simulation

© 2005 Xilinx, Inc. All Rights Reserved

After completing this module, you will be able to:

Objectives

• Identify the blocks necessary for HDL co-simulation• Describe the steps involved in performing HDL co-simulation


Outline

• Introduction• Co-Simulation Support Blocks

– Black Box– Simulation Multiplexer– ModelSim

• HDL Co-Simulation Process• Summary• Lab 2: MAC FIR Filter Verification Using

HDL Co-Simulation


HDL Co-Simulation Supports Legacy Code

• Being able to include legacy code is essential for many DSP system designers

• Legacy (or new) HDL code can be imported into the Simulink tool– A new black box function allows designers to import legacy HDL code– Legacy code can be simulated in the Simulink tool to significantly reduce development

time

• HDL is co-simulated transparently– Legacy HDL can be simulated by using the industry-standard Mentor Graphics ModelSim

or Xilinx ISE Simulator (ISIM) simulation tools directly from the Simulink framework

• A single HDL simulator for multiple black boxes• The time scale in the ModelSim/ISIM tool matches that in the Simulink tool


Using Black Box for HDL Co-Simulation

LegacyHDL

Real-Time VerificationISIM

Simulation


Outline



• HDL Co-Simulation Process• Summary• Lab 2: MAC FIR Filter Verification Using HDL Co-

Simulation


HDL Co-Simulation Support Blocks

• System Generator libraries provide both high-level functions and basic functions for building systems

• You may, however, have IP blocks or have a need to build IP blocks with your HDL modules. These HDL modules must be simulated in conjunction with other System Generator library blocks

• Supported blocks for performing HDL co-simulation– Black Box block– ModelSim block– Simulator Multiplexer block

• The Black Box block provides an interface between the Simulink model and the structural HDL source code

• The ModelSim block provides a means to invoke the ModelSim simulator and the data exchange between the Simulink simulator and the ModelSim simulator


Black Box Block

• The Black Box block provides a way to incorporate non-Xilinx blockset functions into a System Generator model

• It is needed to incorporate hardware description language (VHDL or Verilog) models into System Generator

• The block is used to specify both the simulation behavior in the Simulink tool and the implementation files to be used during code generation with System Generator

• It assumes the interface (ports and parameters) of the function it implements, and its ports produce and consume the same types of signals as other System Generator blocks

• Black box HDL code can be co-simulated with the Simulink tool by using either ModelSim or ISIM simulator


Black Box Requirements

• An HDL component associated with a black box must adhere to the following System Generator requirements and conventions– The entity name must not collide with any other entity name in the design– Bidirectional ports are not allowed on the top-level black box entity– For Verilog black boxes, the module and port names must be lower case

and must follow standard VHDL naming conventions– Any port that is not a clock or clock enable must be of type

std_logic_vector. (For Verilog black boxes, ports must be of vector type; e.g., input[3:0] din; input [0:0] dout)

– Any port that is a clock or clock enable must be of type std_logic (for Verilog black boxes, ports must be of non-vector inputs; e.g., input clk)

• Every non-combinational HDL must have a separate clock and clock enable port for each associated sample rate in the Simulink tool


Black Box Requirements

• Clock and clock enable ports in black box HDL should be expressed as follows – Clock and clock enables must appear as pairs (i.e., for every clock, there is

a corresponding clock enable, and vice-versa)– Although a black box can have more than one clock port, a single clock

source is used to drive each clock port– Only the clock enable rates differ– Each clock name (and clock enable name) must contain the substring CLK

(and CE)– The name of a clock enable must be the same as that for the corresponding

clock, but with CE substituted for CLK. For example, if the clock is named src_clk_1, then the clock enable must be named src_ce_1

• Clock and clock enable ports are not visible on the black box block


Black Box M-Configuration File

• A black box must describe its interface through a MATLAB M-function– For example, ports and generics, its implementation, and optionally, its simulation model

through an HDL co-simulator

• The name of this function must be specified in the block parameter dialog box under the Block Configuration M-Function parameter

• The configuration M-function is generated automatically by the system generator and performs the following:

– Specifies the top-level entity name of the HDL component that should be associated with the black box

– Selects the language (i.e., VHDL or Verilog)– Describes ports, including type, direction, bit width, binary point position, name, and sample

rate– Defines any generics required by the black box HDL– Specifies the black box HDL and other files (e.g., EDIF) that are associated with the block– Defines the clocks and clock enables for the block – Declares whether the HDL has any combinational feed-through paths


Configuration M File

function fir_blackbox_config(this_block) % Revision History: % % 03-Mar-2006 (07:07 hours): % Original code was machine generated by Xilinx's System Generator after parsing % R:\training\dsp_flow\labs\lab3\fir_blackbox.vhd % % this_block.setTopLevelLanguage('VHDL'); this_block.setEntityName('fir_blackbox'); % System Generator has to assume that your entity has a combinational feed through; % if it doesn't, then comment out the following line: this_block.tagAsCombinational;

Specify HDL Language

Specify top-level entity

Pure combinatorial path


Configuration M File this_block.addSimulinkInport('reset'); this_block.addSimulinkInport('din'); this_block.addSimulinkOutport('dout'); dout_port = this_block.port('dout'); dout_port.setType(‘UFix_27_0'); % ----------------------------- if (this_block.inputTypesKnown) % do input type checking, dynamic output type and generic setup in this code block. if (this_block.port('reset').width ~= 1); this_block.setError('Input data type for port "reset" must have width=1.'); end end % if(inputTypesKnown)

Specify data format for ports

Port error checking


Configuration M File if (this_block.inputRatesKnown)

setup_as_single_rate(this_block,'input_clk','input_ce') end % if(inputRatesKnown)

% Add addtional source files as needed.% |-------------% | Add files in the order in which they should be compiled.% | If two files "a.vhd" and "b.vhd" contain the entities% | entity_a and entity_b, and entity_a contains a% | component of type entity_b, the correct sequence of% | addFile() calls would be:% | this_block.addFile('b.vhd');% | this_block.addFile('a.vhd');% |------------- this_block.addFile('coregen\fir.edn');this_block.addFile('coregen\COEF_BUFFER.mif');this_block.addFile('coregen\fir.mif');this_block.addFile('coregen\fir.vhd');this_block.addFile('fir_blackbox.vhd');

Design files including HDL, netlists, Memory initialization files, etc.


Black Box Block Parameters• Specify the name of the

Configuration M-Function that is associated with the black box

• Indicate the Simulation Mode (Inactive or Use HDL Co-Simulation)– When the mode is Inactive, the

black box ignores all input data and writes zeroes to its output ports

– Usually for this mode, the black box should be coupled, using a Simulation Multiplexer block, with a parallel simulation model

• Indicate the helperblock to be used during HDL Co-Simulation


Black Box Block Parameters

• Two simulators support– Xilinx ISIM Simulator

• No helper block needed

– ModelTech ModelSim Simulator

• Set Simulation mode to External Simulator

• Requires ModelSim helper block

• List helper block name


Simulation Multiplexer

• The Simulation Multiplexer is a System Generator block that allows two portions of a design to work in parallel, with simulation results provided by the first portion and hardware providing the second

– This is useful when a subsystem is defined in the usual way with Simulink blocks, but black box HDL is used to implement the subsystem in hardware or black box HDL is used with the HDL Co-Simulator and the simulator is made inactive

– Another use of the multiplexer is to switch between black boxes that incorporate different types of HDL. One black box might provide behavioral HDL to be used in simulation, and the other might provide RTL to be used for implementation


Simulation Multiplexer Block Parameters

• The For Simulation, Pass Through Data from Input Port parameter determines which input port (either 1 or 2) is used for simulation

• The For Generation, Pass Through Data from Input Port parameter determines which input port (either 1 or 2) is used for generation


ModelSim Block• The ModelSim HDL co-simulation block configures and controls co-simulation for one

or several black boxes• The block performs the following

– Constructs the additional VHDL required to allow black box HDL to be simulated inside the ModelSim tool

– Spawns a ModelSim session when a Simulink simulation starts– Mediates the communication between the Simulink and ModelSim tools– Reports whatever errors are detected when black box HDL is compiled– Terminates ModelSim, if appropriate, when the simulation is complete

• During a simulation, each ModelSim block spawns one copy of ModelSim, and, therefore, uses one ModelSim license

• If licenses are scarce, several black boxes can share the same block. Except for minor reductions in flexibility, nothing is lost with this approach

• The time scale in ModelSim matches that in Simulink; i.e., one second of Simulink simulation time corresponds to one second of ModelSim simulation time


ModelSim Block Parameters• The ModelSim block is started in the

directory named by this field– The directory is created, if necessary– The directory can be specified as an

absolute or relative path• When this checkbox is selected, the

ModelSim waveform window opens automatically, displaying a standard set of signals

• When this checkbox is selected, the ModelSim session is left open after the Simulink simulation has finished

• To use Verilog Unisim library check this box

• To specify the script, select Add Custom Scripts and enter the script name (e.g., myscript.do) in the Script to Run After “vsim” field


Outline




Simulation


Yes

No

HDL Import FlowTop-level HDL file to be imported

Import top-level HDL as Sysgen black box

Add HDL, EDN, NGC, MIF filesrequired by the HDL for simulation

and implementation to black boxconfiguration function

Co-simulate black box using ModelSim or ISE Simulator

Create HDL wrapper for the top-level HDL which satisfies black box

requirements.

HDL has clk, ce and ports that match

requirements


ISE Simulator

ModelSim

Co-simulate HDL black boxIn Sysgen

Specify the ModelSim token name as the external co-simulator

Add ModelSim token to desgin

HDL black box to be co-simulated

Specify ISE Simulator as the black box simulation mode

HDL Co-simulation Flow


HDL Co-Simulation (Step 1)

Drag a black boxinto the model

The Configuration Wizarddetects HDL files and customizes the block


HDL Co-Simulation (Step 2)ModelSim

Drag a ModelSimblock into the model

Select the ModelSimSimulation Mode


HDL Co-Simulation (Step 2)ISE Simulator

Select the ISE SimulatorSimulation Mode


HDL Co-Simulation (Step 3)ModelSim Simulator

Select the External co-simulatorSimulation Mode Simulink opens

ModelSim and co-simulates


HDL Co-Simulation (Step 3)ISE Simulator

Select the ISE SimulatorSimulation Mode


Outline




Simulation


Knowledge Check

• Why HDL co-simulation?

• Name supported blocks for HDL co-simulation using ModelSim

• List the steps involved in performing HDL co-simulation using ISIM


Answers

• Why HDL co-simulation?– It provides designers a means to incorporate legacy code in a Simulink-based system

DSP design– Legacy code can be simulated in the Simulink tool to significantly reduce development

time

• Name supported blocks for HDL co-simulation using ModelSim– Black Box– Simulation Multiplexer– ModelSim

• List the steps involved in performing HDL co-simulation using ISIM– Drag a Black Box block into a design and assign the legacy code to it– Select ISE Simulator in simulation mode option– Run the Simulink simulation, which will invoke the ISIM simulator in the background and

feed result back to the scope


Summary

• Black box block provides a means to incorporate HDL model• Black box allows ModelSim and ISE Simulator (ISIM) be invoked

to simulate HDL model• ModelSim simulation flow requires ModelSim helper block• A black box must describe its interface through a MATLAB M-

function• ISE simulator is run in background when invoked through black

box• An HDL component associated with a black box may not have bi-

directional ports at the top-level of hierarchy• Any port that is a clock or clock enable must be of type std_logic


Outline




Simulation


• You will perform the following steps:– Create a MAC FIR using CORE Generator™ – Incorporate the MAC FIR into a System Generator

design by using black box. – Simulate the MAC FIR in Simulink™. – Create a hardware co-simulation block and perform

both hardware and software HDL co-simulation

Lab 2

Documents

© 2005 Xilinx, Inc. All Rights Reserved This material exempt per Department of Commerce license exception TSU HDL Co-Simulation