"Michael N. Moran" <mnmoran@bellsouth.net> wrote in message news:<x895e.30954$vL3.24650@bignews4.bellsouth.net>...
> risha wrote:
> > " 
> >>IANALL, but ulvald is never used, and it is not volatile,
> >>and therefore the compiler likely performs an optimisation
> >>never setting its value.
> >>
> > 
> > first i wanted to check that the value is in the debugger memory
> > window should display correctly which is not happening first the
> > varaible ucvald should be initialized to 0 which shows a junk value on
> > execution of the stmt then the value at the particular location which
> > is passed as a parameter should read the value at the location
> > [(0x8020)which is actually 0x03 in my case]so the value in the memory
> > window should have displayed 0x03 which shows junk value again.
> 
> If you want to prevent the compiler from eliminating
> useless expressions, then you will need to declare the
> variables as "volatile". Try this:
> 
> void FlashReadM(volatile unsigned long *fl_ad,unsigned long abb)
> {
>     volatile unsigned long ulvald; // note volatile qualifier
>     abb=2;  // This will be eliminated since abb is a local copy.
>     ulvald=0; // Now that uvald is volatile, this will show.
>     ulvald= *(fl_ad);
> }


thank you for your time and help. It is really great, now the ulvald
value does get initialized to 0 initially but the next line i.e.
ulvald=*(fl_ad);does not show the correct value 03, it shows junk
value. It should have copied the value at fl_ad into the variable
ulvald right? The value 03 value is not displayed at this location.

NOTE: 0x8020 address is passed as a parameter(fl_ad) to the function
FlashReadM and contains the value as 03(at this location 0x8020)

regards,

risha wrote:
> " 
>>IANALL, but ulvald is never used, and it is not volatile,
>>and therefore the compiler likely performs an optimisation
>>never setting its value.
>>
> 
> first i wanted to check that the value is in the debugger memory
> window should display correctly which is not happening first the
> varaible ucvald should be initialized to 0 which shows a junk value on
> execution of the stmt then the value at the particular location which
> is passed as a parameter should read the value at the location
> [(0x8020)which is actually 0x03 in my case]so the value in the memory
> window should have displayed 0x03 which shows junk value again.

If you want to prevent the compiler from eliminating
useless expressions, then you will need to declare the
variables as "volatile". Try this:

void FlashReadM(volatile unsigned long *fl_ad,unsigned long abb)
{
    volatile unsigned long ulvald; // note volatile qualifier
    abb=2;  // This will be eliminated since abb is a local copy.
    ulvald=0; // Now that uvald is volatile, this will show.
    ulvald= *(fl_ad);
}




-- 
Michael N. Moran           (h) 770 516 7918
5009 Old Field Ct.         (c) 678 521 5460
Kennesaw, GA, USA 30144    http://mnmoran.org

"So often times it happens, that we live our lives in chains
  and we never even know we have the key."
The Eagles, "Already Gone"

The Beatles were wrong: 1 & 1 & 1 is 1

" 
> IANALL, but ulvald is never used, and it is not volatile,
> and therefore the compiler likely performs an optimisation
> never setting its value.
> 
first i wanted to check that the value is in the debugger memory
window should display correctly which is not happening first the
varaible ucvald should be initialized to 0 which shows a junk value on
execution of the stmt then the value at the particular location which
is passed as a parameter should read the value at the location
[(0x8020)which is actually 0x03 in my case]so the value in the memory
window should have displayed 0x03 which shows junk value again.

only when this works should i return the value ie ulvald from this
function to the main program ofcourse changing the void return type of
the function.So i need first the value displayed in the variable
should be correct.Then can i proceed.

any suggestions on this,
regards
risha

risha wrote:
> *****************
> void FlashReadM(volatile unsigned long *fl_ad,unsigned long abb)
> {
>    unsigned long ulvald;
>    abb=2;
>    ulvald=0;
>    //fl_ad=(volatile unsigned long *)0x8020;
>    ulvald= *(fl_ad);
>    //return ucVal;
> }
> 
> in the above prg the value of abb is shown as 2 but the value of
> ulvald does not show 0 it shows a junk value in the debugger memeory
> window
> i initialized the value of the ulvald thinking that could initilize
> the varaiable and then not have this junk value but the junk val just
> stays put.
> 
> any suggestions help extended will be very helpful
> regards,

IANALL, but ulvald is never used, and it is not volatile,
and therefore the compiler likely performs an optimisation
never setting its value.

-- 
Michael N. Moran           (h) 770 516 7918
5009 Old Field Ct.         (c) 678 521 5460
Kennesaw, GA, USA 30144    http://mnmoran.org

"So often times it happens, that we live our lives in chains
  and we never even know we have the key."
The Eagles, "Already Gone"

The Beatles were wrong: 1 & 1 & 1 is 1

thanks for the help i was just trying something and it rather appears
very strange as i dont see any thing wrong in the code no errors or
any indication as to where i am going wrong there is junk value stored
in the varaible which just does not seem to go away what could be the
problem?

*****************
void FlashReadM(volatile unsigned long *fl_ad,unsigned long abb)
{
   unsigned long ulvald;
   abb=2;
   ulvald=0;
   //fl_ad=(volatile unsigned long *)0x8020;
   ulvald= *(fl_ad);
   //return ucVal;
}

in the above prg the value of abb is shown as 2 but the value of
ulvald does not show 0 it shows a junk value in the debugger memeory
window
i initialized the value of the ulvald thinking that could initilize
the varaiable and then not have this junk value but the junk val just
stays put.

any suggestions help extended will be very helpful
regards,

In my group the first thing we do, it is to check the cfi capability of
the flash.

Try putting on the bus the "Auto select" command and verify the flash
response is what you expect. You can try this also by putting the
command directly in a debugger (if you have one).

At least there is a first check whether it is a bus/interface problem
or a broken flash.

David Schmider <david.schmider@gmx.ch> wrote in message news:<4242a0f3$1_3@news.bluewin.ch>...
> risha schrieb:
> > need to know how to write data into external flash
> > memory(offchip).using MCU MC9S12A128B and the external flash memory
> > chip is M29F040B.Is there any special code to be sent to the external
> > flash memory.Using a cpld chip number being CY37128P84 125 JC which is
> > used for the selecting the external flash chip.Also using metrowerks
> > code warrior and BDM Multilink.
> > 
> > 
> > Thanks for any help,
> > Ranjita
> 
> Hi Ranjita
> 
> Here you will find the information you are looking for: 
> http://www.st.com/stonline/books/pdf/docs/6887.pdf
> (There's even some C Code included)

thanks everybody for the help but i have gone through the documents
before i posted this mail but it did not write in the flash memory.So
i had doubt when i was doin the right thing but it seems like i was
right.So the memory location shows just ff so it does not take in the
data i wonder why?

could there be such that the external flash chip has gone bad if so
how to check it?the  document specifies that

Check for correct flash type
Step 2: Check the offset range is valid
Step 3: Check that the block(s) to be programmed are not protected
Step 4: While there is more to be programmed
Step 5: Check for changes from &#4294967295;0' to &#4294967295;1'
Step 6: Program the next byte

one more thing flash was erased so condition has been met.so now what
is that i could be not doing the right way?

thanks for any help,
ranjita

ST produces device manual
(http://www.st.com/stonline/books/pdf/docs/6580.pdf) and Application
Notes with source code example (
http://www.st.com/stonline/books/pdf/docs/6887.pdf) on how to use that
memory device.

About ST SW Drivers, you can do whatever you want with that code as
long as you keep the ST disclaimer in your code.

Dave schrieb:
>>The two attached files were once published on the website of
>>STMicroelectronics (www.st.com) and contain library routines for the
>>M29F040B Flash Memory.
>>
> 
> They are also "Copyright (c) 1999 STMicroelectronics".  Does the license
> allow reproduction and publication?  Or are you breaking the law?
> 
> 
I'm sorry. Posting just the link might be more appropriate.

risha schrieb:
> need to know how to write data into external flash
> memory(offchip).using MCU MC9S12A128B and the external flash memory
> chip is M29F040B.Is there any special code to be sent to the external
> flash memory.Using a cpld chip number being CY37128P84 125 JC which is
> used for the selecting the external flash chip.Also using metrowerks
> code warrior and BDM Multilink.
> 
> 
> Thanks for any help,
> Ranjita

Hi Ranjita

Here you will find the information you are looking for: 
http://www.st.com/stonline/books/pdf/docs/6887.pdf
(There's even some C Code included)