Global Var

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.

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.

rahib,
what happened? where is praise? where is the submission :) :) :) where is the propaganda ?! it is sir erac you are talking about maaaaaaan !!!!

now seriously: your friend did not provide vital data that could have solved his problem earlier and save us time, headache and heartache! instead he offered money. YUK.

HI Eric!!
First thanks for your reply.

My code startup is:
START900.A51 because i use Philips P89LPC936.
It has 512 bytes of xdata.

I have modificated only this:

;  <o> XDATASTART: XDATA memory start address <0x0-0xFFFF>
;      the absolute start-address of XDATA memory
XDATASTART      EQU     0x000
;
;  <o> XDATALEN: XDATA memory length <0x0-0xFFFF>
;      the length of XDATA memory in bytes.
XDATALEN        EQU     0x200
;

i say no!!!!!!

i asking his help and ansewrs and he be ignored me

i think he liking to heat poeple up and spit the bit out yes???

he say lots but not say much for poeple to be using.

now he is not sir but he being something other yes!!!!

why are taking this so seriously? ok, I sometimes also think that I'd rather jump into a swimming pool filled with Pirenia fish rather than being bashes by Erik, but (un)fortunately he often knows what he is talking about (like this one!). so relax and enjoy the bottomless well of knowledge (gee, I'm poetic!)

IF i enable Use On-Chip XRAM i cant compile the aplication because :"ADRESS SPACE OVERFLOW".