Function located to a fixed address

> Thank you, I still feel "in the dark". Is there a step by step
> explanation of the therms used for this scatter script language ie:

LR_IROM1 0x00000000 0x00020000  {    ; load region size_region

A load region describes the memory map before reloction, usually in a
non-volatile memory.

The execution regions define both, the contents of the load region, as
well as the memory map after relocation.

  ER_IROM1 0x00000000 0x00020000  {  ; load address = execution address

ER_IROM1 describes what can stay in flash for proper operation.

   *.o (RESET, +First)

That would be the startup code including vectors. +FIRST means that
this has got to be first in the region. The order in the scatter
loading file has no impact on the actual order of elements.

   *(InRoot$$Sections)

Some portions of the C-library have to be in flash as well. As a short
hand, these are refered to by the name "InRoot$$Sections".

   .ANY (+RO)

Any other read-only portions of the image (code, literal pools) go here.

  }
  RW_IRAM1 0x20000000 0x00008000  {  ; RW data
   .ANY (+RW +ZI)
  }

All variable go into RAM.

}

To get what you want, you'd have to divide your flash into two
regions:

LR_IROM1 0x00000000 0x00020000  {    ; load region size_region
  ER_IROM1 0x00000000 0x0000f000  {  ; load address = execution address
   *.o (RESET, +First)
   *(InRoot$$Sections)
   .ANY (+RO)
  }
  ER_IROM2 +0 (0x00020000-0x0000f000) {
    *.o (ISP_SECTION, +RO)
  }
  RW_IRAM1 0x20000000 0x00008000  {  ; RW data
   .ANY (+RW +ZI)
  }
}

Now all flash space between 0x0000f000 and 0x00020000 can be used for
ISP. You will have to adapt this to your requirements.

> LR_IROM1 is this a reserved word? I can guess IROM1 means internal
> ROM, LR is not clear to me.

The region names are just identifiers. Only some names have a special
meaning (not reserved, though).

> Using the help system and it's examples just leads me to places,
> where experts that already know most of it understand it's full
> meaning, the introductional is too abstact/generic for me.

infocenter.arm.com/.../Degxrsh.html

And don't forget to tell MDK not to clobber your scatter file!
Or give it a different name.

Regards
Marcus
http://www.doulos.com/arm/

> Thank you, I still feel "in the dark". Is there a step by step
> explanation of the therms used for this scatter script language ie:

LR_IROM1 0x00000000 0x00020000  {    ; load region size_region

A load region describes the memory map before reloction, usually in a
non-volatile memory.

The execution regions define both, the contents of the load region, as
well as the memory map after relocation.

  ER_IROM1 0x00000000 0x00020000  {  ; load address = execution address

ER_IROM1 describes what can stay in flash for proper operation.

   *.o (RESET, +First)

That would be the startup code including vectors. +FIRST means that
this has got to be first in the region. The order in the scatter
loading file has no impact on the actual order of elements.

   *(InRoot$$Sections)

Some portions of the C-library have to be in flash as well. As a short
hand, these are refered to by the name "InRoot$$Sections".

   .ANY (+RO)

Any other read-only portions of the image (code, literal pools) go here.

  }
  RW_IRAM1 0x20000000 0x00008000  {  ; RW data
   .ANY (+RW +ZI)
  }

All variable go into RAM.

}

To get what you want, you'd have to divide your flash into two
regions:

LR_IROM1 0x00000000 0x00020000  {    ; load region size_region
  ER_IROM1 0x00000000 0x0000f000  {  ; load address = execution address
   *.o (RESET, +First)
   *(InRoot$$Sections)
   .ANY (+RO)
  }
  ER_IROM2 +0 (0x00020000-0x0000f000) {
    *.o (ISP_SECTION, +RO)
  }
  RW_IRAM1 0x20000000 0x00008000  {  ; RW data
   .ANY (+RW +ZI)
  }
}

Now all flash space between 0x0000f000 and 0x00020000 can be used for
ISP. You will have to adapt this to your requirements.

> LR_IROM1 is this a reserved word? I can guess IROM1 means internal
> ROM, LR is not clear to me.

The region names are just identifiers. Only some names have a special
meaning (not reserved, though).

> Using the help system and it's examples just leads me to places,
> where experts that already know most of it understand it's full
> meaning, the introductional is too abstact/generic for me.

infocenter.arm.com/.../Degxrsh.html

And don't forget to tell MDK not to clobber your scatter file!
Or give it a different name.

Regards
Marcus
http://www.doulos.com/arm/

Thanks Marcus, your extensive explanations gave me a good starting point. Checking out doulos.com made me order the C und C++ für Embedded Systems book.

Werner