Electrically Erasable Programmable Rom; Eeprom Operation; Eeprom Registers - Motorola Semiconductor MC68HC11F1 Technical Manual

6 Electrically Erasable Programmable ROM

The MC68HC11F1 has 512 bytes of electrically erasable programmable ROM (EEPROM). A nonvola-
tile, EEPROM-based configuration register (CONFIG) controls whether the EEPROM is present or ab-
sent and determines its position in the memory map. In single-chip and bootstrap modes the EEPROM
is positioned at $FE00–$FFFF. In expanded and special test modes, the EEPROM can be repositioned
to any 4-Kbyte boundary ($xE00–$xFFF).

6.1 EEPROM Operation

The EEON bit in CONFIG controls whether the EEPROM is present in the memory map. When
EEON = 1, the EEPROM is enabled. When EEON = 0, the EEPROM is disabled and removed from the
memory map. EEON is forced to one out of reset in single-chip and special bootstrap modes to enable
EEPROM. EEON is forced to zero out of reset in special test mode to remove EEPROM from the mem-
ory map, although test software can turn it back on. In normal expanded mode, EEON is reset to the
value last programmed into CONFIG.
An on-chip charge pump develops the high voltage required for programming and erasing. When the
E-clock frequency is 1 MHz or above, the charge pump is driven by the E-clock. When the E-clock fre-
quency is less than 1 MHz, select the internal RC oscillator to drive the EEPROM charge pump by writ-
ing one to the CSEL bit in the OPTION register. Refer to the discussion of the OPTION register in 4.3
System Initialization Registers, page 23.

6.2 EEPROM Registers

BPROT — Block Protect
Bit 7
0
RESET 0
Bits [7:5] — Not implemented. Reads always return zero and writes have no effect.
PTCON — Protect for CONFIG
0 = CONFIG register can be programmed or erased normally
1 = CONFIG register cannot be programmed or erased
BPRT[3:0] — Block Protect Bits for EEPROM
0 = Protection disabled
1 = Protection enabled
Bit Name
BPRT3
BPRT2
PBRT1
BPRT0
Block protect register bits can be written to zero (protection disabled) only once
within 64 cycles of a reset in normal modes, or at any time in special modes. Block
protect register bits can be written to one (protection enabled) at any time.
MC68HC11F1/FC0
MC68HC11FTS/D
NOTE
EEPROM is available on the MC68HC11F1 only.
6 5 4
0 0 PTCON
0 0 1
Table 14 Block Protect Bits for EEPROM
Block Protected
$xEE0–xFFF
$xE60–xEDF
$xE20–xE5F
$xE00–xE1F
NOTE
3 2 1
BPRT3 BPRT2 BPRT1
1 1 1
Block Size
288 Bytes
128 Bytes
64 Bytes
32 Bytes
$x035
Bit 0
BPRT0
1
MOTOROLA
29