User guide

6.6 Using both scatter loading and remapping

This section describes how to convert the application in Loading the ROM image at address 0 into a more complex

scatter-loading application. This example uses memory remapping to exchange the ROM and RAM regions after the

application has started.

The code for this example is in install_directory\Examples\Embedded.

6.6.1 Memory map

Figure 6-5 shows:

• FLASH is at 0x24000000. An aliased copy of the FLASH appears at 0x0 on reset.

• After remapping, 32-bit RAM is at 0x0 to hold the exception vectors.

Figure 6-5 Memory map for remapping

6.6.2 Scatter-load description file

The scatter-load description file shown in Example 6-7 defines one load region (FLASH) and five execution regions:

• FLASH (at 0x24000000) contains all the read-only code and data

• 32bitRAM (at 0x0) contains the vector table from vectors.o

• HEAP (immediately above the RW/ZI data) is the start of the heap

• STACKS (at 0x40000) is the top of the stack

• UART0 (at 0x16000000) contains memory-mapped I/O.

Example 6-7 scat_c.scf

FLASH 0x24000000 0x4000000 ; The load region starts at 0x24000000 and has

; a maximum size of 0x4000000 bytes.

{

FLASH 0x24000000 0x4000000 ; The load and execution addresses are the same.

; Execution region size is less than 0x4000000.

{

init.o (Init, +First) ; The initialization code is placed first.

* (+RO) ; All other RO code and data are placed next.

} ; Library code also goes here.

32bitRAM 0x0000 ; RAM starts at address 0x0.

{

vectors.o (Vect, +First) ; The vector table is placed first in RAM.

* (+RW,+ZI) ; All other RW and ZI regions go after vectors.

}

Writing Code for ROM