To create a user-defined System object™ and generate code:
Create a class that subclasses from matlab.System.
Define one of the following sets of methods:
setupImpl and stepImpl
setupImpl, outputImpl,
and updateImpl
To use the outputImpl and
updateImpl methods, your System object must also inherit from the matlab.system.mixin.Nondirect
class.
Optionally, if your System object has private state properties, define the
resetImpl method to initialize them to zero.
Write a top-level design function that creates an instance of your
System object and calls the step method, or the
output and update methods.
Note
The resetImpl method runs automatically during
System object initialization. For HDL code generation, you cannot
call the public reset method.
Write a test bench function that exercises the top-level design function.
Generate HDL code.
This example shows how to generate HDL code for a user-defined System object that implements the setupImpl and
stepImpl methods.
In a writable folder, create a System object, CounterSysObj, which subclasses from
matlab.System. Save the code as
CounterSysObj.m.
classdef CounterSysObj < matlab.System
properties (Nontunable)
Threshold = int32(1)
end
properties (Access=private)
State
Count
end
methods
function obj = CounterSysObj(varargin)
setProperties(obj,nargin,varargin{:});
end
end
methods (Access=protected)
function setupImpl(obj, ~)
% Initialize states
obj.Count = int32(0);
obj.State = int32(0);
end
function y = stepImpl(obj, u)
if obj.Threshold > u(1)
obj.Count(:) = obj.Count + int32(1); % Increment count
end
y = obj.State; % Delay output
obj.State = obj.Count; % Put new value in state
end
end
end
stepImpl method implements the System object functionality. The setupImpl method
defines the initial values for the persistent variables in the
System object.Write a function that uses this System object and save it as myDesign.m. This
function is your
DUT.
function y = myDesign(u)
persistent obj
if isempty(obj)
obj = CounterSysObj('Threshold',5);
end
y = step(obj, u);
endWrite a test bench that calls the DUT function and save it as
myDesign_tb.m.
clear myDesign
for ii=1:10
y = myDesign(int32(ii));
end
Generate HDL code for the DUT function as you would for any other MATLAB® code, but skip fixed-point conversion.