How to write C code generation for ' not available function for standalone generation' ?

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Julien Pelet 2017-4-27

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评论： Hari Ijjada 2019-8-30

Hi, i can not transfert my matlab algorithme. When I use Matlab Coder to convert it into C code, it build failed with the following error:

The function 'designfilt' is not supported for standalone code generation. See the documentation for coder.extrinsic to learn how you can use this function in simulation.

Then i think i need to write a bandpass filter in C code by myself using DFT and inverse fourier transformation, but i really don't know how to write it. May somebody help me ?

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Jan 2017-4-27

Please do not use # characters in the tags. This is not twitter.

What kind of bandpass filter do you need? As long, as you do not explain this, it is hard to suggest a solution. A full replacement of the designfilt command would be an overkill.

Julien Pelet 2017-4-28

在 MATLAB Online 中打开

Hi Jan, sorry i am new here. I use two different kind of filter, one 'designfilter' and the other 'Least Square' is reported just over there ))

function [td_filtrage]= LeastSquare(Datad,Fs)
N      = 40;   % Order
Fstop1 = 0.7;  % First Stopband Frequency
Fpass1 = 0.9;  % First Passband Frequency
Fpass2 = 1.4;  % Second Passband Frequency
Fstop2 = 1.5;  % Second Stopband Frequency
Wstop1 = 1;    % First Stopband Weight
Wpass  = 1;    % Passband Weight
Wstop2 = 1;    % Second Stopband Weight
   % Calculate the coefficients using the FIRLS function.
b  = firls(N, [0 Fstop1 Fpass1 Fpass2 Fstop2 Fs/2]/(Fs/2), [0 0 1 1 0 ...
           0], [Wstop1 Wpass Wstop2]);
Hd = dfilt.dffir(b);    
td_filtrage = filter(Hd,Datad)

Then when i try to translate in C code, the software send me: Error 'dfilt.dffir' is not supported for code generation.

Thank you to help me !

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Answer 1

Honglei Chen 2017-4-27

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https://ww2.mathworks.cn/matlabcentral/answers/337586-how-to-write-c-code-generation-for-not-available-function-for-standalone-generation#answer_264744

Do you need to change your filter over the simulation, if not, then the coder.extrinsic approach, as outlined in the error message, would be a good way to go. Essentially you can use MATLAB to compute the coefficients and then perform the filtering.

HTH

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Honglei Chen 2017-4-28

在 MATLAB Online 中打开

You are using firls, it actually supports codegen. So I think you just need to make a very simple change. Instead of forming Hd, just use b directly. Like this

function [td_filtrage]= LeastSquare(Datad,Fs)
N      = 40;   % Order
Fstop1 = 0.7;  % First Stopband Frequency
Fpass1 = 0.9;  % First Passband Frequency
Fpass2 = 1.4;  % Second Passband Frequency
Fstop2 = 1.5;  % Second Stopband Frequency
Wstop1 = 1;    % First Stopband Weight
Wpass  = 1;    % Passband Weight
Wstop2 = 1;    % Second Stopband Weight
% Calculate the coefficients using the FIRLS function.
b  = firls(N, [0 Fstop1 Fpass1 Fpass2 Fstop2 Fs/2]/(Fs/2), [0 0 1 1 0 ...
         0], [Wstop1 Wpass Wstop2]);
td_filtrage = filter(b,1,Data);

Now to codegen, you need to ensure that you pass in a constant Fs. You can achieve that using coder.Constant

codegen LeastSquare.m -args {ones(1024,1),coder.Constant(100)}

Once the mex file is generated, you can compare the results as

x = randn(1024,1);
y = LeastSquare(x,100);
yc = LeastSquare_mex(x,100);
max(abs(y-yc))

HTH

Julien Pelet 2017-5-2

在 MATLAB Online 中打开

I fix the problem about the constant Fs, I put this variable insade the LeastSquare function.

function [td_filtrage]= LeastSquare(Datad)
Fs     = 37;   
N      = 40;   % Order
Fstop1 = 0.7;  % First Stopband Frequency
Fpass1 = 0.9;  % First Passband Frequency
Fpass2 = 1.4;  % Second Passband Frequency
Fstop2 = 1.5;  % Second Stopband Frequency
Wstop1 = 1;    % First Stopband Weight
Wpass  = 1;    % Passband Weight
Wstop2 = 1;    % Second Stopband Weight
% Calculate the coefficients using the FIRLS function.
b  = firls(N, [0 Fstop1 Fpass1 Fpass2 Fstop2 Fs/2]/(Fs/2), [0 0 1 1 0 ...
       0], [Wstop1 Wpass Wstop2]);
td_filtrage = filter(b,1,Datad);

Then i change the call code in the Main

td_filtrage = LeastSquare(Datad);

I received my function in C code, i think its working. I need to put the code in my microprocesor . Thank you for everything !!

Hari Ijjada 2019-8-30

i am facing the same issue but instead of bandpass filter i am using low pass filter. how to design the lowpass filter using firls syntax ?

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