MC68HC08AS32A Datasheet, PDF (42/296 Pages) Motorola, Inc – Microcontrollers

Memory
Freescale Semiconductor, Inc.
prior to any EEPROM program or erase operations (see 2.5.1.1 EEPROM
Configuration and 2.5.1.2 EEPROM Timebase Requirements).
2.5.1.3 EEPROM Program/Erase Protection
The EEPROM has a special feature that designates the 16 bytes of addresses from
$08F0 to $08FF to be permanently secured. This program/erase protect option is
enabled by programming the EEPRTCT bit in the EEPROM non-volatile register
(EENVR) to a logic 0.
Once the EEPRTCT bit is programmed to 0 for the first time:
• Programming and erasing of secured locations $08F0 to $08FF is
permanently disabled.
• Secured locations $08F0 to $08FF can be read as normal.
• Programming and erasing of EENVR is permanently disabled.
• Bulk and block erase operations are disabled for the protected locations
$0800–$08EF, $0900–$09FF.
• Single byte program and erase operations are still available for locations
$0800–$08EF and $0900–$09FF for all bytes that are not protected by the
EEPROM block protect EEBPx bits (see 2.5.1.4 EEPROM Block
Protection and 2.5.2.2 EEPROM Array Configuration Register).
NOTE:
Once armed, the protect option is permanently enabled. As a consequence, all
functions in the EENVR will remain in the state they were in immediately before the
security was enabled.
2.5.1.4 EEPROM Block Protection
The 512 bytes of EEPROM are divided into four 128-byte blocks. Each of these
blocks can be protected from erase/program operations by setting the EEBPx bit
in the EENVR. Table 2-2 shows the address ranges for the blocks.
Table 2-2. EEPROM Array Address Blocks
Block Number (EEBPx)
EEBP0
EEBP1
EEBP2
EEBP3
Address Range
$0800–$087F
$0880–$08FF
$0900–$097F
$0980–$09FF
These bits are effective after a reset or upon read of the EENVR register. The block
protect configuration can be modified by erasing/programming the corresponding
bits in the EENVR register and then reading the EENVR register. See 2.5.2.2
EEPROM Array Configuration Register for more information.
NOTE:
Once EEDIVSECD in the EEDIVHNVR is programmed to 0 and after a system
reset, the EEDIV security feature is permanently enabled because the
EEDIVSECD bit in the EEDIVH is always loaded with 0 thereafter. Once this
Data Sheet
42
Memory
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MC68HC08AS32A — Rev. 1
MOTOROLA