AN2400 Freescale Semiconductor / Motorola, AN2400 Datasheet - Page 36

• Manufacturer Part Number: AN2400
• Description: HCS12 NVM Guidelines
• Manufacturer: Freescale Semiconductor / Motorola

AN2400/D
36
NOTE:
The EPOPEN bit in the EPROT register determines whether the entire
EEPROM block is protected. When the EPOPEN bit is erased, the remainder
of the bits in the register determine the state of protection and the size of the
protected block. When the EPOPEN bit is programmed the entire EEPROM
block is protected and the state of the remaining bits within the EPROT register
is irrelevant.
Trying to program or erase any of the protected areas will result in a protection
violation error and bit PVIOL will be set in the EEPROM Status Register
ESTAT. A mass erase of the entire EEPROM block is only possible if protection
is fully disabled, i.e. EPOPEN = 1 or EPDIS = 1.
The EEPROM protection memory locations are located within the upper
protected area of EEPROM block. Therefore if the upper area of EEPROM is
protected, or if the whole of EEPROM is protected, then the EEPROM
protection memory locations themselves are protected and can no longer be
changed.
EPOPEN — EEPROM Protection Open
EPDIS — EEPROM Protection Disable
EP[2:0] — EEPROM Protection Size
The FPHS[1:0] bits determine the size of the protected area.
Protection High Bits
Block.
Freescale Semiconductor, Inc.
For More Information On This Product,
1 = The EEPROM block protection depends on the EPDIS and EP[2:0] bits.
0 = The entire EEPROM block is protected against programming and
1 = The high address range protection is disabled.
0 = The high address range protection is enabled and the size of the
erasure. The EPDIS and EP[2:0] bits have no effect.
protected area depends on the EP[2:0] bits.
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HCS12 NVM Guidelines
Table 7. EEPROM Protection High Bits
FPHS[2:0]
000
001
010
011
100
101
110
111
gives the available sizes for a 4k byte EEPROM
Protected Size (4k Block)
128 bytes
192 bytes
256 bytes
320 bytes
384 bytes
448 bytes
512 bytes
64 bytes
Table 5. Flash
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