MC68HC08AS32 Datasheet, PDF (40/280 Pages) Motorola, Inc – M68HC08 Family of 8-bit microcontroller units (MCUs)

2.5.1.4 EEPROM Redundant Mode
To extend the EEPROM data retention, the array can be placed in redundant
mode. In this mode, the first 256 bytes of user EEPROM array are mapped to the
last 256 bytes. Reading, programming and erasing of the first 256 EEPROM bytes
($0800–$08FF) will physically affect two bytes of EEPROM. Addressing the last
256 bytes will not be recognized. Block protection still applies but EEBP3 and
EEBP2 are meaningless.
NOTE: Before entering redundant mode, program the EEPROM in non-redundant mode.
2.5.1.5 EEPROM Configuration
The EEPROM non-volatile register (EENVR) contains configurations concerning
block protection and redundancy. EENVR is physically located on the bottom of the
EEPROM array. The contents are non-volatile and are not modified by reset. On
reset, this special register loads the EEPROM configuration into a corresponding
volatile EEPROM array configuration register (EEACR). Thereafter, all reads to the
EENVR will reload EEACR.
The EEPROM configuration can be changed by programming/erasing the EENVR
like a normal EEPROM byte. The new array configuration will take effect with a
system reset or a read of the EENVR.
2.5.1.6 EEPROM Control Register
This read/write register controls programming/erasing of the array.
Address: $FE1D
Bit 7
6
5
4
3
2
1
Read: _EEBCLK
0
EEOFF EERAS1 EERAS0 EELAT
0
Write:
R
R
Reset:
0
0
0
0
0
0
0
R
= Reserved
Figure 2-3. EEPROM Control Register (EECR)
Bit 0
EEPGM
0
NOTE:
EEBCLK — EEPROM Bus Clock Enable Bit
This read/write bit determines which clock will be used to drive the internal
charge pump for programming/erasing. Reset clears this bit.
1 = Bus clock drives charge pump.
0 = Internal RC oscillator drives charge pump.
Use the internal RC oscillator for applications in the 3- to 5-V range.
Data Sheet
40
MC68HC08AS32 — Rev. 4.1
Freescale Semiconductor