Technical information

AN2216/D

10 MC9S12DP256 Software Development Using Metrowerk’s Codewarrior MOTOROLA

CodeWarrior Linker

Linking Compiled

Code Modules

Before presenting an example linker command file for the MC9S12DP256, a

short discussion on memory addresses used by the linker is necessary. The

Codewarrior development tools view the MC9S12DP256’s program memory

expansion space as a logical address space. For non-paged memory, the

logical address corresponds to the physical address. For paged memory, the

logical address is composed of the PPAGE value followed by the page window

address. This simple approach is intuitive and easy to understand.

Figure 9. Logical Address to PPAGE/Window Address Correspondence

The important thing to realise is that Flash address $4000 to $7FFF

corresponds to the same physical memory as $3E8000 to $3EBFFF. Therefore

code cannot be linked to address range $4000 to $7FFF and $3E8000 to

$3EBFFF. Code must be linked to address range $4000 to $7FFF or $3E8000

to $3EBFFF. Due to the necessity to have some code in non-page memory and

the advantage of constant data in non-page memory, $4000 to $7FFF is

usually chosen in preference to $3E8000 to $3EBFFF. Similarly Flash address

PPAGE Value Window Address Logical Address Memory type

N/A $4000 – $7FFF $4000 – $7FFF Flash Block 0, non-paged

N/A $C000 – $FFFF $C000 – $FFFF Flash Block 0, non-paged

$30 $8000 – $BFFF $308000 – $30BFFF Flash Block 3, paged

$31 $8000 – $BFFF $318000 – $31BFFF Flash Block 3, paged

$32 $8000 – $BFFF $328000 – $32BFFF Flash Block 3, paged

$33 $8000 – $BFFF $338000 – $33BFFF Flash Block 3, paged

$34 $8000 – $BFFF $348000 – $34BFFF Flash Block 2, paged

$35 $8000 – $BFFF $358000 – $35BFFF Flash Block 2, paged

$36 $8000 – $BFFF $368000 – $36BFFF Flash Block 2, paged

$37 $8000 – $BFFF $378000 – $37BFFF Flash Block 2, paged

$38 $8000 – $BFFF $388000 – $38BFFF Flash Block 1, paged

$39 $8000 – $BFFF $398000 – $39BFFF Flash Block 1, paged

$3A $8000 – $BFFF $3A8000 – $3ABFFF Flash Block 1, paged

$3B $8000 – $BFFF $3B8000 – $3BBFFF Flash Block 1, paged

$3C $8000 – $BFFF $3C8000 – $3CBFFF Flash Block 0, paged

$3D $8000 – $BFFF $3D8000 – $3DBFFF Flash Block 0, paged

$3E $8000 – $BFFF $3E8000 – $3EBFFF Flash Block 0, paged

$3F $8000 – $BFFF $3F8000 – $3FBFFF Flash Block 0, paged