HT-CM400 NXP Semiconductors, HT-CM400 Datasheet - Page 93

• Manufacturer Part Number: HT-CM400
• Description: Ht Cm400; Ht Rm440 Family; Ht Rm800 Family Interface Protocol Reader - Host
• Manufacturer: NXP Semiconductors

98-02-10
The mechanism to protect security relevant data in the read/write device has 3 levels:
Level 0:
Level 1:
Level 2:
You cannot reset levels, e.g. from level 2 to level 1. Once a security level has been chosen it
becomes irreversible.
The functionality of this mechanism is based on the control bytes Control_RW (only for HITAG
1), Control_WO (only for HITAG 1) and Control_LT (only for HITAG 2). All control bytes are
located in EEPROM of the read/write device.
On delivery of a read/write device all bits of Control_RW, Control_WO and Control_LT are
set to 1, except Bit 7 of CONTROL_RW (serial number).
The data cannot be read any more. If you want to change an entry, you have to
know the old value. Otherwise writing access will be denied.
The internal data are locked and can neither be read nor written. At this level it is
impossible for the user to change the stored data.
All security relevant data can be read and written.
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