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The CFM module has hardware interlocks to protect data from accidental corruption. The
CFM memory array is logically divided into 16-Kbyte sectors for the purpose of data
protection and access control. A flexible scheme allows the protection of any combination
of logical sectors (see Section 6.3.4.4, "CFM Protection Register (CFMPROT)"). A similar
mechanism is available to control supervisor/user and program/data space access to these
sectors.
6.3.1
CFM Configuration Field
The CFM configuration field comprises 24 bytes of reserved array memory space that
determines the module protection and access restrictions out of reset. Data to secure the
Flash from unauthorized access is also stored in the CFM configuration field. Table 6-1
describes each byte used in this field.
Address Offset (from array base
address)
0x0000_0400–0x0000_0407
0x0000_0408–0x0000_040B
0x0000_040C–0x0000_040F
0x0000_0410–0x0000_0413
0x0000_0414–0x0000_0417
6.3.2
Flash Base Address Register (FLASHBAR)
The configuration information in the Flash base address register (FLASHBAR) controls the
operation of the Flash module.
• The FLASHBAR holds the base address of the Flash. The MOVEC instruction
provides write-only access to this register.
• The FLASHBAR can be read or written from the debug module in a similar manner.
• All undefined bits in the register are reserved. These bits are ignored during writes
to the FLASHBAR, and return zeroes when read from the debug module.
• The back door enable bit, FLASHBAR[BDE], is cleared at reset, disabling back
door access to the Flash.
MOTOROLA
Table 6-1. CFM Configuration Field
Size
in Bytes
8
Back door comparison key
4
Flash program/erase sector protection
Blocks 0H/0L (see Section 6.3.4.4, "CFM Protection Register (CFMPROT)")
4
Flash supervisor/user space restrictions
Blocks 0H/0L (see Section 6.3.4.5, "CFM Supervisor Access Register
(CFMSACC)")
4
Flash program/data space restrictions
Blocks 0H/0L (see Section 6.3.4.6, "CFM Data Access Register
(CFMDACC)")
4
Flash security longword (see Section 6.3.4.3, "CFM Security Register
(CFMSEC)")
Chapter 6. ColdFire Flash Module (CFM)
Memory Map
Description
6-5
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