Motorola M68EVB912B32, User Manual

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OPERATION
68EVB912B32UM/D 3-55
NOTE
D-Bug12 sets the default value of the user’s stack pointer to
$0A00. This is not a mistake. The M68HC12’s stack pointer
points to the last byte that was pushed onto the stack, rather than to
the next available byte on the stack, as the M68HC11 does. The
M68HC12 first decrements its stack pointer, then stores data on the
stack. The M68HC11 stores data on the stack and then decrements
its stack pointer.
3.8.2 Memory Map
Table 3-5. Factory-Configuration Memory Map
Address Range Usage Description
$0000 - $01FF CPU registers on-chip registers
$0800 - $09FF
$0A00 - $0BFF
user code/data
reserved for D-Bug12
1K on-chip RAM
$0D00 - $0FFF user code/data 768 bytes on-chip EEPROM
$8000 - $F67F
$F680 - $F6BF
$F6C0 - $F6FF
$F700 - $F77F
$F780 - $F7FF
$F800 - $FBFF
$FC00 - $FFBF
$FFC0 - $FFFF
D-Bug12 code
user-accessible functions
D-Bug12 customization data
D-Bug12 startup code
interrupt vector jump table
reserved for bootloader expansion
EEPROM bootloader
reset and interrupt vectors
32 Kbytes on-chip Flash
EEPROM
3.9 OPERATIONAL LIMITATIONS
In EVB mode, D-Bug12 requires many of the MC68HC912B32’s resources for execution. In
this mode, the EVB cannot provide true emulation of a target system. These limitations are
described in the following sections.
If target-system emulation is required, the EVB may be reprogrammed and controlled via the
BDM interface. Operation as a target is described in 3.1.3 POD (Probe) Mode.