mc68hc05pv8a Freescale Semiconductor, Inc, mc68hc05pv8a Datasheet - Page 165

• Manufacturer Part Number: mc68hc05pv8a
• Description: Mc68hc05pv8a Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

14.4 EEPROM Protection Mechanism
MC68HC(8)05PV8/A — Rev. 1.9
PGMB – Programming enable
In order to achieve a higher degree of protection, inadvertent
programming of the EEPROM can be avoided by use of the EEPRT bit
of the options register. As long as this bit is not active (= 0), the whole
array, except the first 4 bytes, can be erased or programmed. As soon
as the EEPRT bit is active (= 1), the EEPROM is protected and becomes
a read-only memory in single chip mode. Note that programming cannot
be done by software executed from this EEPROM array!
Any attempt to erase or program a location in single-chip mode will then
be unsuccessful. Then the EEPROM can be programmed only in
bootloader mode. If the EEPRT bit is then cleared (not protected), the
EEPROM will stay protected until the next power-on or external reset.
controls the activation of the charge pump. The charge pump is not
affected by WAIT mode, thus it is possible to wait the t
or t
read mode when entering STOP mode.
When cleared, this bit allows programming of the EEPROM. It can
only be cleared if the LATB is already cleared and at least one
EEPROM write has occurred. This bit must be set when changing the
address and data for programming new data. It is automatically set
when LATB is set.
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1 = EEPROM read state
0 = Activate charge pump; address and data may be latched for
1 = EEPROM programming is inhibited
0 = EEPROM programming is enabled
PROG
EEPROM write.
programming time in WAIT mode. The EEPROM is set to
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Program EEPROM
EEPROM Protection Mechanism
Program EEPROM
ERA
Technical Data
erase time