The MC68HC908AB32 is a member of the low-cost, high-performance
M68HC08 Family of 8-bit microcontroller units (MCUs) with embedded
EEPROM for user data storage. All MCUs in the family use the
enhanced M68HC08 central processor unit (CPU08) and are available
with a variety of modules, memory sizes and types, and package types

Extended Security:

To further disable monitor mode functions, an extended security
command keyword can be programmed at FLASH locations
$FFC0-$FFC7. The keyword is eight bytes long with a 7-byte ASCII
string and 1-byte $00 delimiter. The keyword for the MC68HC908AB32
MCU is "PSWDOPT" + $00.
Entry to monitor mode with extended security command keyword
programmed, the MCU stops communicating with the host after
transmitting a break character if the host fails the security bypass as
described in 10.5 Security.
NOTE: Once the extended security command keyword is programmed, the
FLASH memory cannot be erased without a valid security code
(matching $FFF6-$FFFD). Therefore, the extended security command
keyword should not be programmed during software development.


The 8-bit EEPROM non-volatile register (EENVR) contain
the default settings for the following EEPROM configurations:
- Security option
- Block protection
The EEPROM has a special security option, enabled by programming
the EEPRTCT bit to 0 in the EEPROM non-volatile register (EENVR).
Once security is enabled, the following limitations apply to the EEPROM:
- The 16-byte EEPROM locations from $08F0 to $08FF are
protected from erase and program operations.
- The block erase and bulk erase modes are disabled. Byte erase
can be used for all EEPROM locations except $08F0 to $08FF.
- The EENVR is protected from further erase or program operations.

The EENVR is factory programmed with $10.


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 a 0
thereafter. Once this security feature is armed, erase and program
operations are disabled for EEDIVHNVR and EEDIVLNVR.
Modifications to the EEDIVH and EEDIVL registers are also disabled.
Therefore, care should be taken before programming a value into the
EEDIVHNVR.