MC68HC08AZ32A Datasheet, PDF (61/456 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
EEPROM
Functional Description
As the CGMXCLK or bus clock is user selected, the EEPROM Timebase
Divider Register must be configured with the appropriate value to obtain
the 35 µs. The timebase divider value is calculated by using the following
formula:
EEDIV= INT[Reference Frequency(Hz) x 35 x10^-6 +0.5]
This value is written to the EEPROM Timebase Divider Register
(EEDIVH and EEDIVL) or programmed into the EEPROM Timebase
Divider Non-Volatile Register prior to any EEPROM program or erase
operations(see EEPROM Configuration on page 60 and EEPROM
Timebase Requirements on page 60).
5.5.3 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 zero.
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 unprotected
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
EEPROM Block Protection on page 62 and EEPROM Array
Configuration Register on page 69).
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.
MC68HC08AZ32A — Rev 1.0
MOTOROLA
EEPROM
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Technical Data
61