Global Var

Always Im debugging my code, i trying everythings and im seeing for webs and datasheet.
And i dont know where is the problem. Im exasperate!!!

Thanks.

Always Im debugging my code, i trying everythings and im seeing for webs and datasheet.
And i dont know where is the problem. Im exasperate!!!

Thanks.

I see some serious problems with your implementation.
I think your integrator is totally wrong - you do not even accumulate the error!
it should be something like this:

double UpdatePID(SPid * pid, double error, double position)
{
  double pTerm, dTerm, iTerm;

  pTerm = pid->pGain * error;

  // calculate the proportional term
  // calculate the integral state with limiting

  pid->iState += error;
  if (pid->iState > pid->iMax) pid->iState = pid->iMax;
  else if (pid->iState < pid->iMin)
  {
     pid->iState = pid->iMin;
     iTerm = pid->iGain * iState;
  }

  dTerm = pid->dGain * (position - pid->dState);
  pid->dState = position;

  return pTerm + iTerm - dTerm;
}

If your "real" is "(signed) int" I'm in doubt if you thought about scaling, underflow and overflow of our variables.

sorry, you do accumulate the error but I still think your implementation is not correct.

Thanks for your reply.
But i think that the problem is not the implementation because is a simple acumulate.
I dont understand why this var not acumulate the old value.

The var values in my debugging are 10, 4 ,... im trying change the data type for unisgned int and is the same.

Let me give you simple example with signed int (-32768 to +32767).
In mathematical notation:

SP=3000 (setpint)
PV=0 (value read from ADC)
Kp=12
P=KP*(SP-PV)=12*(3000-0)=36000

This causes an overflow. The result is treated as a negative number.

I understand your example.
But in my code i have this:

First iteraction
SP=10 (setpint)
PV=0 (value read from ADC)
Kp=1
P=KP*(SP-PV)=1*(10-0)=10

Second iteraction
SP=10 (setpint)
PV=6 (value read from ADC)
Kp=1
P=KP*(SP-PV)=1*(10-6)=4

but my pid->iState should be 10+4=14, and it is 4

i dont know why dont save the old value in pid->iState

Are There Anybody that help me with my project??
Maybe i can send the code for see it!!!

It is very important for me!!
Thanks

You've checked only this part of your code?
You have to ensure, that there is no underflow/overflow/division by 0 in the whole code and under all circumstances (for example extreme user input).
The "updating problem":
It helps a lot if you screw down your code to the interesting core and debug it. If this fails you can show this very short program and all the necessary information to the forum.
And don't forget to mention the controller, hardware, RTX. Check the datasheet of the controller and the camera. It seems you didn't.

Sorry. "Camera" belongs to an other thread I read in parallel.

OK!
Im working with an emulator (EPM900) and an evaluation board (MCB900), my micro is Philips P89LPC936, under RTX-51.

Independent of my PID, the problem is the var update.
For example:

void Write (void) _task_ WRITE _priority_ 1 {
        int Ub=0;
        while (1){
              Ub+=1;
              TXRX_putByte(Ub); //send to serial port
        }
void main (void){
        os_start_system (WRITE);

}

The var Ub always is 1, never update the value
???????

Recently i debugg my code in the simulator of uvision and all var are updated!!!
Why dont work in my board?????????

Recently i debugg my code in the simulator of uvision and all var are updated!!!
Why dont work in my board?????????
DUH, the simulator simulates.

if there is e.g. a baudrate error, the simulating thing will still work, if the internal XRAM in the device is not enabled the simulating thing will still work, ....

if the var you are hunting is in xdata, I'll bet you dollars to doughnuts that you have not modified startup.a51 to enable your XDATA.

Erik

if the var you are hunting is in xdata, I'll bet you dollars to doughnuts that you have not modified startup.a51 to enable your XDATA.

BTW this newfangled thing that only few know about called a datasheet will tell you what is needed.

looking at the Keil manual and the startup code will show you why this must be at the start of startup.a51.

Erik

java

you be please ignoring sir eracs terrrible sarcasem.

he is be thinking he be funny,,, but he is just crazy yes.