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Bits
Name
0:1
SBEN
Small block enable. When SBEN[M]=0, the corresponding small block M behaves logically as if
the small block is still part of the larger host block. In addition, the small block protect bit
(SBPROTECT[M]), the small block supervisor bit (SBSUPV[M]), the small block data bit
(SBDATA[M]), and the small block BLOCK bit (SBBLOCK[M]) corresponding to small block M
have no effect. The corresponding small block is controlled by the same protect, supervisor, data,
and block bits that control its host block.
When SBEN[M] = 1, the corresponding small block M can be programmed and erased
independently of its host block. The corresponding small block protect bit, the small block
supervisor bit, the small block data bit, and the small block bit are enabled by SBEN.
For example: when SBEN[0] = 0, Small Block 0 (16 Kbytes) and the residual block (48 Kbytes)
contained in the host block of Small Block 0 are programmed and erased as if the two blocks are
one large array block (64 Kbytes). When SBEN[0] = 1, small block 0 and the residual block
contained in the host block of small block 0 behave as two separate blocks, i.e. small block 0 and
the residual block in small block 0's host block can be programmed and erased independently of
each other.
0 small block M behaves as part of the host block
1 small block M functions independent of host block
2:3
SBSUPV
Small block supervisor space. Each small array block of the UC3F EEPROM may be mapped
into supervisor or unrestricted address space. When small array block M is mapped into
supervisor address space, SBSUPV[M] = 1, only supervisor accesses are allowed. When small
block M is mapped to unrestricted address space, SBSUPV[M] = 0, both supervisor and user
accesses are allowed.
If SBEN[M] = 0, the corresponding small block M is logically part of the host block and
SBSUPV[M] has no effect. Instead, the corresponding SUPV[M] bit will be used to determine if
the small block is mapped to Supervisor or Unrestricted address space.
Like the SUPV[0:7] bits, the SBSUPV bits are not actually used in the UC3F EEPROM module
but are used by the BIU to determine access restrictions to the UC3F array. Block addresses are
decoded in the BIU to determine which small array block is selected, and the selected small
block's SBSUPV bit is compared with the address space attributes to determine validity of an
array access.
0 small block M is placed in unrestricted address space
1 small block M is placed in supervisor address space
4:5
SBDATA
Small block data space. Each small array block of the UC3F EEPROM may be mapped into data
or both data and instruction address space. When a small array block is mapped into data
address space, SBDATA[M] = 1, only data accesses will be allowed. When a small array block
is mapped into both data and instruction address space, SBDATA[M] = 0, both data and
instruction accesses will be allowed.
If SBEN[M] = 0, the corresponding small block M is logically part of the host block and
SBDATA[M] has no effect. Instead, the corresponding DATA[M] bit will be used to determine if
the small block is mapped to Data or to both Data and Instruction address space.
Like the DATA bits, the SBDATA bits are not actually used in the UC3F EEPROM module but are
used by the BIU to determine access restrictions to the UC3F array. Block addresses are
decoded in the BIU to determine which small array block is selected, and the selected small
block's SBDATA bit is compared with the address space attributes to determine validity of an
array access.
0 small block M is placed in both Data and Instruction address spaces
1 small block M is placed in Data address space
MOTOROLA
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
Table 19-4. UC3FMCRE Bit Descriptions
Chapter 19. CDR3 Flash (UC3F) EEPROM
Description
Programming Model
19-9
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