Freescale Semiconductor Demonstration Board for Freescale MC9S12XHY256 Microcontroller DEMO9S12XHY256 DEMO9S12XHY256 Manual De Usuario

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Freescale Semiconductor

The Flash module contains no signals that connect off-chip.

This section describes the memory map and registers for the Flash module. Read data from unimplemented
memory space in the Flash module is undefined. Write access to unimplemented or reserved memory space
in the Flash module will be ignored by the Flash module.

The S12X architecture places the P-Flash memory between global addresses 0x7C_0000 and 0x7F_FFFF
as shown in

. The P-Flash memory map is shown in

.

The FPROT register, described in

, can be set to protect regions in the Flash memory from

accidental program or erase. Three separate memory regions, one growing upward from global address
0x7F_8000 in the Flash memory (called the lower region), one growing downward from global address
0x7F_FFFF in the Flash memory (called the higher region), and the remaining addresses in the Flash
memory, can be activated for protection. The Flash memory addresses covered by these protectable regions
are shown in the P-Flash memory map. The higher address region is mainly targeted to hold the boot loader
code since it covers the vector space. Default protection settings as well as security information that allows
the MCU to restrict access to the Flash module are stored in the Flash configuration field as described in

.

0x7C_0000 – 0x7F_FFFF

256 K

P-Flash Block 0
Contains Flash Configuration Field
(see

0x7F_FF00 – 0x7F_FF07

8

Backdoor Comparison Key
Refer to

,” and

0x7F_FF08 – 0x7F_FF0B

2

4

Reserved

0x7F_FF0C

1

P-Flash Protection byte

.

Refer to

0x7F_FF0D

1

D-Flash Protection byte

.

Refer to

0x7F_FF0E

1

Flash Nonvolatile byte
Refer to