Freescale Semiconductor MPC5553, Reference Manual

Page: 534 / 1208

MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
Freescale Semiconductor 13-11
29 ERS Erase. Used to set up flash for an erase operation. A 0 to 1 transition of ERS initiates a
flash erase sequence. A 1 to 0 transition of ERS ends the erase sequence. ERS can be
set only in a normal operating mode read (STOP and PGM are low). ERS can be cleared
by the user only when ESUS and EHV are low and DONE is high. ERS is cleared on reset.
0 Flash is not executing an erase sequence.
1 Flash is executing an erase sequence.
30 ESUS Erase suspend. Indicates that the flash module is in erase suspend or in the process of
entering a suspend state. The flash module is in erase suspend when ESUS = 1 and
DONE = 1. ESUS can be set high only when ERS and EHV are high and PGM is low. A 0
to 1 transition of ESUS starts the sequence which sets DONE and places the flash in erase
suspend. ESUS can be cleared only when DONE and EHV are high and PGM is low. A 1
to 0 transition of ESUS with EHV = 1 starts the sequence which clears DONE and returns
the flash module to erase mode. The flash module cannot exit erase suspend and clear
DONE while EHV is low. ESUS is cleared on reset.
0 Erase sequence is not suspended.
1 Erase sequence is suspended.
31 EHV Enable high voltage. Enables the flash module for a high voltage program/erase operation.
EHV is cleared on reset. EHV must be set after an interlock write to start a program/erase
sequence. EHV may be set, initiating a program/erase, after an interlock write under one
of the following conditions:
• Erase (ERS = 1, ESUS = 0).
• Program (ERS = 0, ESUS = 0, PGM = 1, PSUS = 0).
• Erase-suspended program (ERS = 1, ESUS = 1, PGM = 1, PSUS = 0).
If a program operation is to be initiated while an erase is suspended the user must clear
EHV while in erase suspend before setting PGM.
In normal operation, a 1 to 0 transition of EHV with DONE high, PSUS and ESUS low
terminates the current program/erase high voltage operation.
When an operation is aborted
2
, there is a 1 to 0 transition of EHV with DONE low and the
suspend bit for the current program/erase sequence low. An abort causes the value of PEG
to be cleared, indicating a failed program/erase; address locations being operated on by
the aborted operation contain indeterminate data after an abort.
A suspended operation cannot be aborted. EHV may be written during suspend. EHV must
be high for the flash to exit suspend. EHV may not be written after a suspend bit is set high
and before DONE has transitioned high. EHV may not be set low after the current suspend
bit is set low and before DONE has transitioned low.
0 Flash is not enabled to perform a high voltage operation.
1 Flash is enabled to perform a high voltage operation.
1
In an erase-suspended program, programming flash locations in blocks which were being operated on in the erase
may corrupt flash core data. This should be avoided due to reliability implications.
2
Aborting a high voltage operation will leave flash core addresses in an indeterminate data state. This may be
recovered by executing an erase on the affected blocks.
Table 13-6. FLASH_MCR Field Descriptions (Continued)
Bits Name Description