User guide

6.5 Loading the ROM image at address 0

Scatter loading provides a flexible mechanism for mapping code and data onto your memory map. These options are

described in detail in the Linker and Utilities Guide.

The scatter-load description file, scat_b.scf, for this example is in

install_directory\Examples\Embedded\embed.

6.5.1 Memory map

Figure 6-4 shows:

• ROM is fixed at 0x0 and is not remapped

• RAM is at 0x28000000 to hold the data, stack and heap

• memory-mapped I/O for a UART is at 0x16000000.

Figure 6-4 Memory map for simple scatter loading

6.5.2 Scatter-load description file

The scatter-load description file shown in Example 6-2 defines:

• one load region, ROM_LOAD, at 0x0

• five execution regions:

— ROM_EXEC (at 0x0) contains all the read-only code, including the library code. The exception vector table

in vectors.o is placed first in this region. All other read-only code (*) is placed after vectors.o.

— RAM (at 0x28000000) contains the RW and ZI data regions for the application.

— HEAP immediately above the ZI data. The object heap.o contains a symbol that is used to set up the

heap base. The heap grows up from this address.

— STACKS at 0x28080000. The object stack.o contains a symbol that is used to set up the stack top.

Stacks grow downward from this address.

— UART0 at 0x16000000. The object uart.o contains symbols that are used to reserve the

memory-mapped I/O.

Note

The UNINIT entry means that the marked regions are not zero-initialized by the C library initialization code.

Example 6-2 scat_b.scf

ROM_LOAD 0x0

{

ROM_EXEC 0x0

{

Writing Code for ROM