[SOLVED] Placing an Array in Flash

I've defined the following in a C++ file and it isn't referenced by anything. I'm just trying to configure the 16 bytes used by the Kinetis K64 flash protection mechanism..

static const U8 _flash_protection[] __attribute__ ((section(".flash_protection"))) =
{
    0xDE, 0xAD, 0xDE, 0xED,
    0xDE, 0xAD, 0xDE, 0xED,
    0xFF, 0xFF, 0xFF, 0xFF,
    0xFF, 0xFF, 0xFF, 0xFF,
};

I'd like to place it at 0x400 but this doesn't seem to work:

<ProgramSection alignment="4" load="Yes" keep="Yes" name=".flash_protection" start="0x400" size="16" />

It seems to work fine for my vector placement:

<ProgramSection alignment="0x100" load="Yes" name=".vectors" start="$(FLASH_START:)" />

I'm using MacOS SES 4.10a.

Thanks.

Hi Nino,

I am aware of this code. Can you answer my question? Why does that not work? What is the correct way to do this? I don't understand why that wouldn't place those 16 bytes at 0x400.

Can you elaborate on the differences between the "allow security" selection? While I appreciate that you make efforts to ease development it's important to understand what is actually being done by the debugger or the source files that are copied to the project.

Related: What is the option to configure the J-Link to verify the download? The output suggests that 0.000 seconds were spent verifying. I can't seem to find the option. I did find the menu option to do so but I would have found this issue much faster if the flash verify had been enabled. At the moment I am using the J-Link Lite but have a J-Trace Pro in transit for this project. I replaced the firmware on the K64-TWR on-board debugger.

Now that I have purchased a license I'll send a support request and point to this.

Thanks.

I created a separate assembly file:

.section .flashsecurity, "ax"
BACKDOORKEY:
  .byte 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
FPROT:
  .byte 0xff, 0xff, 0xff, 0xff
FSEC:
  .byte 0xfe
FOPT:
  .byte 0xff
FEPROT:
  .byte 0xff
FDPROT:
  .byte 0xff

Then used the following in my flash placement file:

<!DOCTYPE Linker_Placement_File>
<Root name="Flash Section Placement">
  <MemorySegment name="$(FLASH_NAME:FLASH)">
    <ProgramSection alignment="0x100" load="Yes" name=".vectors" start="$(FLASH_START:)" />
    <ProgramSection alignment="4" load="Yes" keep="Yes" name=".flashsecurity" start="0x400" size="16" />

This is satisfactory but I'd like to understand why my original approach did not work.

I was able to link the above and place the bytes correctly but I changed the device to the "allow security" version. Now I'm running in to errors when attempting to download the application.

I realize that I effectively included these bytes but changed to the "allow security" version of the chip which is incorrect. But if I don't define those bytes and place them at 0x400 what will prevent the linker from writing odd data to that special location?

I don't believe that first point is true. I had not included that code and wasn't trying to link two sections to the same place. What I had done was define the vector table in C++ as an array and placed that in the section .vector. But I understand that I am asking too much for you to debug this issue without the actual code.

I have the solution above which is based on the code you pointed out so that's fine. If the linker placement issue comes up again I'll submit an isolated project to recreate the problem.

Thank you for the other information.