custom NOINIT section initializes my variable

Christopher Carl

Other Parts Discussed in Thread: MSP430F5328

Hello,

I am having a lot of trouble getting a variable to be located at a specific location in RAM while also declaring it as a NOINIT variable.

In my linker file I have the section defined as:

.BATTERY_INFO_SECTION : {} > BATTERY_INFO type=NOINIT // Do not initialize the battery information

Where BATTERY_INFO is assigned to 0x1c00 with a length of 8.

In my code I have a variable defined as follows:

#pragma DATA_SECTION(_batMod_totalEnergy, ".BATTERY_INFO_SECTION")
volatile unsigned long long _batMod_totalEnergy;

However, When i run on the debugger, I see that variable getting initialized to 0 after every soft reset (watchdog instigated).

If i don't put it in a specified data section and just label it as #pragma NOINIT() then it works, however I still need to force the variable to specified location in RAM.

I am using CCS 5.4.0.00091 and compiler version 4.1.5. My board is a MSP430F5328, so while this doesn't have FRAM, I should still be able to maintain the value across soft resets.

Everything I have read has indicated this should work, so I am at a loss. Any help would be greatly appreciated!

over 11 years ago

0 Brian Boorman over 11 years ago

Guru 25210 points

Read this thread: http://e2e.ti.com/support/microcontrollers/msp430/f/166/p/248615/871158.aspx#871158

0 Christopher Carl over 11 years ago in reply to Brian Boorman

Intellectual 350 points

Thanks for the reply Brian. I read through the forum and I am still having issues.

At this point I can set the variable with the NOINIT pragma and it works, and I can set its location using the SET_DATA_SECTION pragma. However, my issue is when I try to combine the two. By using the two pragmas together I get a warning that says you cannot use NOINIT when a variable has been assigned to a specific data section. After reading, it appeared the fix is to add the type=NOINIT next to the data section specification in the linker command file. However, when i do this, and run it, i see the variable gets initialized to 0 anyways at startup, even after a soft-reset.

0 Brian Boorman over 11 years ago in reply to Christopher Carl

Guru 25210 points

I am not a CCS user so I can't help much with the pragma solution.

One other option would be to exclude the memory location from the linker command file. So instead of RAM starting at 0x5000 (as an example) modify linker file so RAM memory starts at 0x5008.

Then, in a header file, define a macro for accessing the hard coded memory address 0x5000, like this:

// Define macro for accessing hard coded storage location
#define _batMod_totalEnergy   *(unsigned long long *)(0x5000)

...

  _batMod_totalEnergy = 105693;

...
  if (_batMod_totalEnergy == _some_value) { ...

etc.

0 Christopher Carl over 11 years ago in reply to Brian Boorman

Intellectual 350 points

Excellent suggestion! As I don't really have the time to try and delve into the issue here, your work-around works perfect. Thanks so much!

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custom NOINIT section initializes my variable