HOW TO ? Non Volatile and Persistent Variables on FRAM Devices

Hi Freedo,

i was the one who originally wrote the wiki page.

have you chosen the EABI output format? As far as i remember this is really necessary since it won't work with the old COFF format output.

Hey thanks,

Yes I did check that I was using EABI but I couldn't get my variables to be Persistent and they are always initialized ...

Great, I think you make a point here ! It does work now ...

I read these erase options when troubleshooting this issue but it wasn't very explicit about what it was actually doing ... 

I'm getting desperate ...

It does work on some variables but when I put all my variables into FRAM and want some to be Initialized (cleared at Start-up) and some to be Persistent (keep their value forever) then it is all not working ..

Instead of what I expect, my variables are indeed stored into FRAM but each time I even use the Restart button all my variables that I watch in the "Expression" panel get cleared...

I've tried the other method using the

#pragma PERSISTENT(xyz)
int xyz=25;

but this doesn't work either ...

So to summarize what I've got :

A Var_FRAM.h file with all my Variables I wanna store in FRAM:

This file is like this :

#pragma SET_DATA_SECTION(".fram_data_init")

Some variables

..........

#pragma SET_DATA_SECTION()

#pragma SET_DATA_SECTION(".fram_data_noinit")

Some other variables

..........

#pragma SET_DATA_SECTION()

the section .fram_data_init is defined in the linker file :

.fram_data_init : {} > FRAM_DATA_INIT 

.fram_data_noinit : {} > FRAM_DATA_NOINIT type=NOINIT

And the memory is mapped :

FRAM_DATA_INIT : origin = 0xF380, length = 0x0980 // Variable INIT length 0x980 (2400 byte)

FRAM_DATA_NOINIT : origin = 0xFD00, length = 0x0280 // Variable NOINIT length 0x280 (640 byte)

I've also changed the debug dowmload options (as described in the earlier post) 

But I can't figure out why these variables would still be cleared/reset each time while on some projects it does work... 

Thanks for having a try at solving this conundrum with me !

Then I'll be able to add lots of good tips to the wiki for others to get it working much faster than myself !

Hi Freedo,

did you checked your settings in theproject properties under Debug->MSP430 Properties->Erase Options ?

Thanks Leo,

It does work for a variable. But how can I make it works even for a variable with a fix address inside this memory segment? what I want to achieve is the same: "...give initialization value only at load/compile time. This initialization value will appear in the binary file which will be downloaded into the FRAM device, but it will not be initialized during C startup." Thanks.

MEMORY
{
    .............
    FRAM_VARS               : origin = 0xC200, length = 0x0080
    .............
}

SECTIONS
{
    .............
    .fram_vars : {} > FRAM_VARS type=NOINIT
    .............
}

in the main.h
#define fram_var_char =(unsigned char *) (0xC210)

in the main.c

#pragma SET_DATA_SECTION(".fram_vars")

* char fram_var_char = 2;

#pragma SET_DATA_SECTION()

it doesn't work. the compiler reports incompatible error.