Global Var

Erik Did respond. He noted - as several others - that you supplied to little info for anyone to come with suggestions. He also noted that you seemed to be doing things you where not comfortable with, and I would think most other readers would agree.

I asked you for the function implementation, since it is the function that will assign any new values to your global variable. By the way - why a pointer to a global variable? Do you have multiple global variables of the same type, and sometimes send the address to one variable, and sometimes the address to another?

You said: "The funtion implementation i think that is not important to resolve my problem."

If the function does not perform any assign using the pointer, then your global variable will not be updated. Obviously the implementation of the function seems to be very, very relevant, don't you think?

Another thing - real is int? Is that your own data type, or an assumption about the Keil float? Every programmer who sees the name "real" will map into their brain the very obvious notation that real is NOT an integer. A real should be a floating point value - or in some situations maybe a fixed-point value. But when you work with finite-resolution fixed-point values, you normally name them according to their size, just so you always know how many decimals you have. This is very important when multiplying two fixed-point numbers which produces twice as many decimals as the original numbers had.

Erik Did respond. He noted - as several others - that you supplied to little info for anyone to come with suggestions. He also noted that you seemed to be doing things you where not comfortable with, and I would think most other readers would agree.

I asked you for the function implementation, since it is the function that will assign any new values to your global variable. By the way - why a pointer to a global variable? Do you have multiple global variables of the same type, and sometimes send the address to one variable, and sometimes the address to another?

You said: "The funtion implementation i think that is not important to resolve my problem."

If the function does not perform any assign using the pointer, then your global variable will not be updated. Obviously the implementation of the function seems to be very, very relevant, don't you think?

Another thing - real is int? Is that your own data type, or an assumption about the Keil float? Every programmer who sees the name "real" will map into their brain the very obvious notation that real is NOT an integer. A real should be a floating point value - or in some situations maybe a fixed-point value. But when you work with finite-resolution fixed-point values, you normally name them according to their size, just so you always know how many decimals you have. This is very important when multiplying two fixed-point numbers which produces twice as many decimals as the original numbers had.

Thanks Per!!!

real is my data type, now is int but i created this for future changes.

The implementation is important Yeah!!! but i think that it is OK:

error = SP - PV;

                P = pid->Kp*error;
                if (pid->Ti){
                        I = pid->iState*(pid->Kp*(pid->Ts/pid->Ti)+ pid->Kwindup);
                        pid->iState = pid->iState + error;
                }else I=0;
                if (pid->Td){
                        D = (pid->Kp*(pid->Td/pid->Ts)*(PV - pid->dState));
                        pid->dState = PV;
                }else D=0;
                v = P + I + D;

this is a piece of code.
For example the pid->iState it is not updated!!!

I dont know where is the problem.

Have you made sure that your function thinks pid->Ti is non-zero, so it has a reason to update pid->iState?

In this funtion, i return pid->iState, first this var returned 10 and after returned 4 and should return 14.

are you actually writing into the piece of memory pointed by iA? show that please...

This is my PID task, it should update the iA, but not to do it!!

void PIDa (void) _task_ A _priority_ 1 {


        Ua = UpdatePID (&iA, SPa, PVa, 1, 4);

        os_send_signal(WRITE);

        os_delete_task(A);

}

This is my PID task, it should update the iA, but not to do it!!

Without seeing the code of updatePID, it is impossible for anyone to tell what the function does and what not.

As long as you keep information scarce, all you're going to get is speculation.

OK, well!! I explain the code:

-I have a global var type struct.
-I have 2 task: WRITE task: here create PID task PID task: here call to the funtion that update the those struct.

This is the piece of code:

PID.H

typedef int real;

typedef struct {

real dState;            /* Ultima posicion             */
real iState;            /* Estado del integrador       */
real uMax,uMin;     /* Saturacion del actuador     */
real Kp;                    /* Ganancia proporcional       */
real Ti,Td;                     /* Cte, tiempo integral y derivativo        */
real Ts,Tt;                     /* Periodo muestreo, Cte. tiempo tracking   */
real Kwindup;           /* Cte. antireset windup                    */

} SPid;

real UpdatePID (SPid *pid, real SP, real PV, unsigned int AUTO,real Uman) reentrant{
         into PID.c
         ....
         pid->iState += error;
         return pid->iState;
}

MAIN.C

//global var
SPid iA

void Write (void) _task_ WRITE _priority_ 1{
           .....
           os_create_task(A);
           os_wait(K_SIG, WAIT_FOREVER,0);
           os_clear_signal(WRITE);
}

void PIDa (void) _task_ A _priority_ 1 {
           ...
           Ua = UpdatePID (&iA, SPa, PVa, 1, 4);
           os_send_signal(WRITE);
           os_delete_task(B);
}

the iA var never update