DATA_SEG with Kinetis development

[iancull]

My company has been using Freescale (HCS12X) parts for more than 10 years with CodeWarrior development.

We now want to use the Kinetis KE06Z part for a new lower code development. I have the FRDM-KE06Z board and have code running on it, using the CodeWarrior Development Studio V1.06. But as I progress I'm running into troubles.

My problem today started with the support or lack of support for #pragma. My research so far suggests there is NO SUPPORT for "#pragma DATA_SEG", for example. Is this true?

I want to place variables into specific memory locations so that both the normal project software, and the bootloader, can access the same data. How do I do this - in the past I used the DATA_SEG and then set up the linker to place that segment somewhere specific.

If no support for DATA_SEG, what is the alternative?

Documentation online is very confusing perhaps due to the Freescale / NXP business but also because there seems to be two separate development systems (the other is Kinetis Design Studio I think).

I wonder if I have chosen the wrong dev suite - where is any helpful information on which is the better choice, what the differences are, etc?

In any case does Kinetis Design Studio support "#pragma DATA_SEG"?

Thank you.

Ian Cull. PG Trionic Inc

Essex, MA, USA

[BlackNight · Accepted solution]

Hi Ian,

things are a bit different in GNU/gcc/ld land. So yes, there is no such pragma CODE_SEG or DATA_SEG. Pragmas are very compiler specific.

But there is the very flexible __attribute__ in GNU land, e.g.:

static unsigned char __attribute__((section (".mySection"))) ucHeap[configTOTAL_HEAP_SIZE];

Additionally, you need to understand a bit the GNU linker file. Maybe have a look here which discusses a specific case how to allocate a variable in a special section:

FreeRTOS Heap with Segmented Kinetis K SRAM | MCU on Eclipse

Related on that topic, this might be helpful too: Defining Variables at Absolute Addresses with gcc | MCU on Eclipse

I hope this helps,

Erich

[iancull]

Many thanks, and fast! That "Defining Variables at Absolute Addresses with gcc" looks like it might be very much what I need, I'll try modifying my pragmas to match and see how it goes.

[iancull]

With that help, I'm done :smileyhappy:

In the linker file, I split off 16 bytes of memory:

MEMORY

{

  m_data      (rwx) : ORIGIN = 0x1FFFF800, LENGTH = 8K - 16 /* SRAM */

  m_fixedboot    (rwx) : ORIGIN = 0x200017F0, LENGTH = 16 /* SRAM */

}

And I set up a new section to fill it:

  .FIXEDBOOT_DATA :

  {

    *(.FIXEDBOOT_DATA1)

    *(.FIXEDBOOT_DATA2)

    *(.FIXEDBOOT_DATA3)

  } > m_fixedboot 

And in the memory definitions C code I labeled the variables (I did it this way in three section attributes since the order appeared unpredictable if I just put all in the same section):

byte __attribute__((section (".FIXEDBOOT_DATA1"))) ramFlashCodes[4];

byte __attribute__((section (".FIXEDBOOT_DATA2"))) ramResetData[4];

longword __attribute__((section (".FIXEDBOOT_DATA3"))) ramPowerUpCheck;

Perfect, thanks.

[Jiun_Yong]

HI Ian

Like you, our company has used HSC12X for years and I am getting to grips with Kinetis for a new project (specifically the KL26).

As you noted, there is no direct equivalent of the #pragma DATA_SEG.

The downside of the method you have used is that you have to insert the __attribute__ ((section(".mydata"))) statement into every declaration for constants.

The alternative is to use the linker file to put all constant data from a given source file into the specified memory area as follows:

1. Put your constant data into a separate source file. In my project, it's called "changer_data.c"

It can be defined simply as "const byte ramFlashCodes[4];" etc.

2. in the MEMORY{} block define a segment of memory where the data will be stored.

E.g.   m_changer_data (R) : ORIGIN = 0x00003600, LENGTH = 0x00001000

3. In the SECTIONS{} segment, add a statement that directs all output from the source file with the constant data to this segment. E.g.

  .m_changer_data_seg :

  {

  . = ALIGN(4);

  *changer_data.o (.rodata .rodata*)

  . = ALIGN(4);

  } > m_changer_data

This will take all the compiled output from "changer_data.c" and link it into the m_changer_data area of memory.

I got this from another post by Eric Styger at Putting Code of Files into Special Section with the GNU Linker | MCU on Eclipse

Hope this helps