MSP430FR2355: FRAM data is not persistent after power cycle

richard wilson

Part Number: MSP430FR2355

Hi,

I am trying to store time data in FRAM . I have set up a struct to store the data and I believe I am using the correct method of setting up SYSCFG0 to save the data. However, the data is not persistent after a power cycle. Is my method o

 
 
 #pragma PERSISTENT(time_array)
 
 struct activation_time
{
    unsigned int month;
    unsigned int day;
    unsigned int hour;
    unsigned int minute;
    unsigned int second;
    unsigned int level;
};

struct activation_time time_array[100];
 
 
 main()
 {
 	unsigned int index;
 	SYSCFG0 = FRWPPW | PFWP;
    time_array[index].month=  RX_buffer[0xB];
    time_array[index].day=    RX_buffer[0xA];
    time_array[index].hour=   RX_buffer[0x8];
    time_array[index].minute= RX_buffer[0x7];
    time_array[index].second= RX_buffer[0x6];
    time_array[index].level = adcResult;
    SYSCFG0 = FRWPPW | DFWP | PFWP;             // Program FRAM write protected (not writable)
    
    if ( index <=99) {index++;}
    
  
 }

f saving a struct allowed?

Thanks in advance

Richard

over 2 years ago

0 richard wilson over 2 years ago

Intellectual 585 points

I realise that I haven't included the index while loop in the code snippet from my actual code. The actual code includes such a loop.

0 Bruce McKenney over 2 years ago

Guru 100745 points

Were you able to see (e.g. with the debugger) that the data was actually written?

DFWP applies to Information FRAM. Persistent() data is normally placed down at the beginning of Program FRAM, under the control of PFWP. (You can see how this happens in the linker .cmd file and/or the .map file.)

Try clearing PFWP instead. You might also try putting the structure in Information FRAM with something like:

> #pragma DATA_SECTION(time_array, ".info")

0 richard wilson over 2 years ago in reply to Bruce McKenney

Intellectual 585 points

Thank you for replying Bruce. I can see that the data is being written with the debugger and I have another routine that dumps the contents of the registers to serial port on boot up(not shown for clarity) and I have also checked the registers with the debugger. . Doesn't PFWP put the data in the program memory space rather than the data space?

0 Seth Jackson over 2 years ago in reply to richard wilson

Expert 2050 points

What does your linker file look like? If PERSISTENT isn't defined anywhere in the linker file, the C runtime will reinitialize the variables each time the MCU is reset.

There is another thing to keep in mind. If you're debugging the device, each time you load code into the MCU, the "PERSISTENT" variables will be re-initialized unless you change some debugger settings from their defaults.

0 Bruce McKenney over 2 years ago in reply to richard wilson

Guru 100745 points

I just noticed this:

> struct activation_time time_array[100];

A Persistent() variable must be explicitly initialized. When I tried something equivalent, I got a Warning and the variable was placed in SRAM (.bss). Check your .map file to see where your variable ended up.

Try instead something like:

> struct activation_time time_array[100] = {0,};

0 richard wilson over 2 years ago in reply to Seth Jackson

Intellectual 585 points

Thank you Seth,

.TI.Persistent is present in the linker file.

0 richard wilson over 2 years ago in reply to Bruce McKenney

Intellectual 585 points

Thanks bruce,

I tried implementing that initialization and strangely , i can no longer write /or read sensible values from the structure. Not sure I understand that..

0 Bruce McKenney over 2 years ago in reply to richard wilson

Guru 100745 points

Before it was in SRAM (always writeable/ephemeral). Now it is in Program FRAM, so you have to set PFWP=0 to write to it.

0 richard wilson over 2 years ago in reply to Bruce McKenney

Intellectual 585 points

It WORKED!!! Thanks a lot bruce- where do I send the holiday card? So the lesson here is that to be persistent the variable has to be initialized and that stores the variable in the program space and not the data space.

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MSP430FR2355: FRAM data is not persistent after power cycle