MC68HC05B6_13 Datasheet, PDF (197/302 Pages) Freescale Semiconductor, Inc – Microcontrollers

E.3.5 EEPROM options register (OPTR)
Options (OPTR)⁽¹⁾
Address bit 7 bit 6 bit 5 bit 4 bit 3
$0100
(1) This register is implemented in EEPROM; therefore reset has no effect on the individual bits.
bit 2
bit 1
bit 0
State
on reset
EE1P SEC Not affected
EE1P – EEPROM protect bit
In order to achieve a higher degree of protection, the EEPROM is effectively split into two parts,
both working from the VPP1 charge pump. Part 1 of the EEPROM array (32 bytes from $0100 to
$011F) cannot be protected; part 2 (224 bytes from $0120 to $01FF) is protected by the EE1P bit
in the options register.
1 (set)
– Part 2 of the EEPROM array is not protected; all 256 bytes of
EEPROM can be accessed for any read, erase or programming
operations.
0 (clear) – Part 2 of the EEPROM array is protected; any attempt to erase or
program a location will be unsuccessful.
When this bit is set to 1 (erased), the protection will remain until the next power-on or external
reset. EE1P can only be written to ‘0’ when the E1LAT bit in the EEPROM control register is set.
Note: The EEPROM1 protect function is disabled while in bootstrap mode.
SEC — Secure bit
This bit allows the EPROM and EEPROM1 to be secured from external access. When this bit is
in the erased state (set), the EPROM and EEPROM1 content is not secured and the device may
be used in non user mode. When the SEC bit is programmed to ‘zero’, the EPROM and EEPROM1
content is secured by prohibiting entry to the non user mode. To deactivate the secure bit, the
EPROM has to be erased by exposure to a high density ultraviolet light, and the device has to be
entered into the EPROM erase verification mode with PD1 set. When the SEC bit is changed, its
new value will have no effect until the next power-on or external reset.
1 (set) – EEPROM/EPROM not protected.
0 (clear) – EEPROM/EPROM protected.
MC68HC05B6
Rev. 4.1
MC68HC705B16
14
Freescale
E-9