
CDR3 Flash (UC3F) EEPROM
MPC561/MPC563 Reference Manual, Rev. 1.2
21-28
Freescale Semiconductor
21.3.8.2
Erasing Shadow Information Words
The shadow information words are erased with either the lowest numbered block or small block 0,
depending on the array configuration and the state of SBEN[0]. If the lowest numbered block in the array
does not host a small block, then the shadow information words are erased with the lowest numbered
block. If the lowest numbered block hosts a small block, then the shadow information words may get
erased with small block 0. If SBEN[0] = 0 for this array configuration, then the shadow information words
get erased with the lowest numbered block. If SBEN[0] = 1 for this same array configuration, then the
shadow information words get erased with small block 0 only.
21.3.8.3
Erase Suspend
The erase operation may be suspended to allow read accesses to the array. Setting the HSUS bit in the
UC3FCTL to a 1 while EHV=1 and HVS=1 forces the array into an erase suspend state. The deassertion
of the HVS bit (HVS = 0) signifies that the erase operation has been successfully suspended. The HVS bit
should negate within 10 ms of asserting the HSUS bit.
While in erase suspend mode, normal read accesses may be performed to the UC3F array or shadow
information words. Reads to the array block or blocks targeted for erase return indeterminate data since
only a partial erase operation has been performed.
The erase operation may be resumed by setting HSUS = 0.
NOTE
Repeated suspending of an erase operation to fetch array contents may
severely extend the erase operation. The internal erase hardware may only
resume the erase operation at predefined steps of the internal erase hardware
sequence; interrupting the erase operation on a high frequency basis may
cause the internal erase hardware to delay completion of the current step and
delay advancement to the next step of the internal erase hardware sequence.
21.3.9
Stop Operation
The UC3F EEPROM goes into a low power operation, or stop operation, while STOP = 1. When the STOP
bit is set, only the control registers can be accessed on the UC3F EEPROM module. The UC3F EEPROM
array may not be programmed, erased or read while STOP = 1.
S5
Erase Suspend Operation:
The erase operation is suspended to either read
the array or disable the module. Once HVS reads
as a 0, the erase operation is suspended. Normal
reads to the array can be performed if the module
is enabled; read accesses to locations in blocks
being erased return indeterminate data.
S1
T10
Reset.
S4
T9
Write HSUS = 0 or re-enable the
UC3F module.
Table 21-8. Erase Interlock State Descriptions (continued)
State
Mode
Next
State
Transition Requirement