transfer function command to use in 'Matlab function block'

Hello friends,

I desinged IIR Bandpass filter using R,L,C values and usinf 'tf' command I got the transfer function of that filter. similarly I converted it from continuous to discrete 'c2d'.

Now I need to use this .m file for code generation. Is it possilbe to use direct m-file? If I use matlab-function block which is used to generate c/c++ code. This bloock is not accepting 'tf' command for code generation.

and similarly 'grpdelay' command is also not accepted by this block. Can anyone help me with this problem please.

function filter_tf
Ts = 1e-7 ;
Fs = 1/Ts ;
% Bandpass filter
F1 = 190000 ;
F2 = 4000000 ;
F = [F1, F2] ;
W1 = 2*pi*F1 ;
W2 = 2*pi*F2 ;
BF = (W2 - W1) ;
W0 = sqrt(W1 * W2) ;
W12 = 1/(W0 * W0) ;
Q = W0 / BF ;
Fr = sqrt(F1 * F2) ;
R = 100 ;
C = (1/(BF*R)) ;
L = (W12 / C) ;

N = 1/(R * C) ;
D1 = 1/(R * C) ;
D2 = 1/(L *C) ;
Fc = 1/(2*3.14*sqrt(L * C)) ;
RC = R * C ;
LC = L * C ;
RL = R / L ;
Wc = 1/(2 * pi * Fc);

% Implementing Continious transfer function
F1 = tf([N 0],[1 D1 D2]) ;
continnious_transfer_function_bandpass = tf(F1)
% % Continious to discrete using Bilinear Z-Transformation
discrete_transfer_function_bandpass = c2d(continnious_transfer_function_bandpass,Bandpass.Ts,'tustin')

thanks in advance

Answer 1

[Azzi Abdelmalek]

The function tf is not allowed for code generation, I suppose the function c2d is also not allowed, then you need to find another way to do it. But first, you have to tell us how the the result of c2d will be used, depending on this, there maybe some suggestions

[sai guduguntla]

I will be using these filter coefficients in 'discrete transfer function' in simulink.

[Azzi Abdelmalek]

Then you can Use this chart with the continuous transfer function

[sai guduguntla]

thank you for the help but I am using 'fixed step' with 'discrete(no continious state)' in simulink

which will not accept continious states

[Azzi Abdelmalek]

You can set a fixed step with those solvers: http://www.mathworks.com/help/simulink/ug/types-of-solvers.html#f11-56725

[sai guduguntla]

thank you for the help and I have another doubt.

'grpdelay' is also not accepted for code generation. So Is there any other way to find the group delay of filter with the help of input and output of that filter?

[Azzi Abdelmalek]

I have no idea