Hardware Reference
In-Depth Information
The programming and erasure of the EEPROM are similar to those of the flash memory.
Both the sector and bulk erasures are supported. An erased bit reads 1 and a programmed bit
reads 0. The high voltage required for programming and erasure is generated internally by an
on-chip charge pump.
The discussion of the HCS12 on-chip EEPROM will be based on the 4-kB EEPROM avail-
able in the HCS12DP256.
The EEPROM can be mapped to any 2-kB boundary, as explained in Section 14.3.3. The
memory map of the 4-kB EEPROM is illustrated in Figure 14.18. The whole 4 kB of EEPROM
can be protected by setting the EPOPEN bit of the EPROT register. A 16-byte field is reserved
inside the EEPROM module from the address $_FF0 to $_FFF. The byte at $_FFD stores the
EEPROM protection information. The EEPROM has hardware interlocks that protect data from
accidental corruption. A protected sector is located at the higher address end of the EEPROM
block, just below $_FFF. The protected sector can be sized from 64 bytes to 512 bytes.
EEPROM_start = $_000
EEPROM control
(base+$110)
registers (12 bytes)
(base+$11B)
3.5 kB
$_E00
$_E40
$_E80
$_EC0
$_F00
$_F40
$_F80
$_FC0
EEPROM_END = $_FFF
EEPROM-protected high sectors
64, 128, 192, 256, 320, 384,
448, 512 bytes
$_FF0
,
$_FFF, EEPROM
protection/reserved field
Figure 14.18
■
HCS12 4-kB EEPROM memory map
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