MATLAB: How to convert const real_T value to double

const real_tconvertincompatible

Hi, I have a problem with a piece of my code:

    static void mdlOutputs(SimStruct *S, int_T tid)
    {  
    #ifndef MATLAB_MEX_FILE
    InputRealPtrsType uPtrs = ssGetInputPortRealSignalPtrs(S,0); 
    ds1104_slave_dsp_pwm_duty_write_register(task_id, &ch1_index, 1);
  
    if (*uPtrs < 1.0)
  ds1104_slave_dsp_pwm_duty_write(task_id, ch1_index, 0.0);
    else
  ds1104_slave_dsp_pwm_duty_write(task_id, ch1_index, 1.0);  
    #endif
    }

It doesn't work because of incompatible operand types ("const real_T *" and "double") here : " *uPtrs < 1.0 "

I don't know how to correct it, your help will be welcome.

Thanks

Best Answer

Hi,

the function ssGetInputPortRealSignalPtrs allows Simulink to have the inputs organized in chunks. That's good for optimization (and for large input arrays) but is more difficult for the user. My suggestion would be to use the simpler ssGetInputPortRealSignal:

const real_T *u = ssGetInputPortRealSignal(S,0); 
if (*u < 1.0)
...

Otherwise, if you leave it as is:

if (u[0][0] < 1.0)

Titus

Related Solutions

MATLAB: S-function and input data

To access the S-function input data, you need to have access to the Simstruct pointer (the S argument in all S-function callback methods), which needs to be passed in.

At best, you can have a global variable to cache the pointer to the input signal that you could update right before calling spinDisplay(). Note that global data is shared if you have multiple instances of the S-function in your model, so you must only use it to cache the pointer just before calling your function.

I'm not entirely confident that this is the best solution, but there's an idea for you to try.

MATLAB: Is there an example available on how to initialize the states in a C-MEX S-function via input signals

Following is an example showing how to initialize the states in a C-MEX S-function via input signals in Simulink.

In this example the Van der Pol equations are used. To initialize the two states x1 and x2 in the equations via input signals the mdlInitializeConditions has been used. If you open up the S-function source file, you will notice the following lines in mdlInitializeConditions:

real_T *x = ssGetContStates(S);
InputRealPtrsType uPtrs0       = ssGetInputPortRealSignalPtrs(S,0);
InputRealPtrsType uPtrs1       = ssGetInputPortRealSignalPtrs(S,1);
/*  init x1 */
x[0] = *uPtrs0[0];
/*  init x2 */
x[1] = *uPtrs1[0];

Here at the beginning of simulation the input signals *uPtrs0 and *uPtrs1 are assigned to the states x1 and x2.

Best Answer

Related Solutions

MATLAB: S-function and input data

MATLAB: Is there an example available on how to initialize the states in a C-MEX S-function via input signals

Related Question