XBYTE [] Addressing Problem

Dear,

I have called the function in the following manner

Write(0x0050,'x');

While defining I used following format.

void Write(unsigned char xdata* Addr,char element)

While writing I have given this code after setring the EECON register.

(*Addr) = element;

But I am unable to write to EEPROM.

CODE:

#define BUSY EECON = EECON & 0X01
#define E_EECON EECON  = EECON | 0X02
#define D_EECON EECON = EECON & 0X00


Write(unsigned char xdata* Addr, char element)
{
  while(BUSY)
  EA = 0;
  E_EECON;
  *Addr = element;
  D_EECON;
  EA = 1;
}

Dear,

I have called the function in the following manner

Write(0x0050,'x');

While defining I used following format.

void Write(unsigned char xdata* Addr,char element)

While writing I have given this code after setring the EECON register.

(*Addr) = element;

But I am unable to write to EEPROM.

CODE:

#define BUSY EECON = EECON & 0X01
#define E_EECON EECON  = EECON | 0X02
#define D_EECON EECON = EECON & 0X00


Write(unsigned char xdata* Addr, char element)
{
  while(BUSY)
  EA = 0;
  E_EECON;
  *Addr = element;
  D_EECON;
  EA = 1;
}

So then, expanding the macros and adding one set of braces to aid visualization, we have:

Write(unsigned char xdata* Addr, char element)
{
    while(EECON = EECON & 0X01) {
        EA = 0;
    }
    EECON  = EECON | 0X02;
    *Addr = element;
    EECON = EECON & 0X00;
    EA = 1;
}

Is that what you intended?

Dear,

Sorry for what I have sended the code actually the code was while(BUSY); was the code.

Please regreet the mistake.

OK then. What about the EECON assignment inside the 'while' condition? It is legitimate C and might be your intention, but I'm just checking on that too.

To answer my own question regarding your intention, that can't be your intention. The assignment clears the EEE bit, disabling the EEPROM space.

Yes, I just went ahead and spent time downloading the datasheet to quickly determine this for myself, never having used the device before.

Dear,

The problem is thar this device contains internal XRAM and EEPROM how to write at the specific location in the EEPROM.

Actually I used seprate pointer variable which contains the address where the data has to be stored but it is not storing in the EEPROM.

Kindly send the program which solves the above problem that would be great help form U.

Nevermind that. I see that EEPROM can be deselected while checking BUSY.

I do still think that an assignment in the 'while' condition is unwarranted. Better to have:

#define BUSY (EECON & 0x01)

Dear Dan Henry,

It would be Great help if u could kindly send the code for writing and reading the EEPROM,

The problem with internal XRAM and EEPROM Addressing is causing problem to us,

With Regards,

Murali

Also, although you have not stated that you are doing so, you shouldn't be using the toolchain's LARGE memory model because the function parameters would not be accessible after setting EEE.

Dear,

Thank you giving this information I will try this now and come back to you.

Can I assign the function parameter to the local variable and use it while clearing EEE.

Please inform me.

"Can I assign the function parameter to the local variable and use it while clearing EEE."

If you are using the LARGE memory model, those autos would not be accessible either.

If you are using the LARGE memory model, it would be best to write this function in assembly language where you can load up registers with the parameters before switching to EEPROM access.

Dear Dan Henry,

Thanx for u kind reply , It was a great help for us.,

we expect the same in future.,

Thanking u ,

Murali

Thanking u

thanking micro

is that the opposite of thanks a lot?

Erik

Dear,

Can I use Global variable and use after setting EEE register

Please reply

"Can I use Global variable and use after setting EEE register"

Note that EEE is a bit - not a register.

Your problem is accessing XDATA - see the description of the EEE bit in the datasheet.
It makes no difference whether the variabe is global or "automatic" - the problem is with accessing XDATA.

So, as long as you don't attempt to access anything in XDATA while EEE is set, you should be OK...