PXD20RM Datasheet, PDF (821/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

Table 21-3. MCR Field Descriptions (continued)
Field
Description
PEG
Program/Erase Good. The PEG bit indicates the completion status of the last flash program or erase sequence for
which high voltage operations were initiated. The value of PEG is updated automatically during the program and
erase high voltage operations. Aborting a program/erase high voltage operation causes PEG to be cleared,
indicating the sequence failed. PEG is set to a 1 when the module is reset. PEG is read only.
The value of PEG is valid only when PGM = 1 and/or ERS = 1 and after DONE transitions from 0 to 1 due to an abort
or the completion of a program/erase operation. PEG is valid until PGM/ERS makes a 1 to 0 transition or EHV makes
a 0 to 1 transition. The value in PEG is not valid after a 0 to 1 transition of DONE caused by PSUS or ESUS being
set to logic 1. If PGM and ERS are both 1 when DONE makes a qualifying 0 to 1 transition the value of PEG indicates
the completion status of the PGM sequence. This happens in an erase-suspended program operation.
0 Program or erase operation failed.
1 Program or erase operation successful.
PGM
Note: If program or erases are attempted on blocks that are locked, the response from flash is PEG = 1, indicating
that the operation was successful, and the contents of the block are properly protected from the program or
erase operation.
Program. PGM is used to set up flash for a program operation. A 0 to 1 transition of PGM initiates a program
sequence. A 1 to 0 transition of PGM ends the program sequence. PGM can be set only under one of the following
conditions:
• User mode read (ERS is low and UTE is low).
• Erase suspend (ERS and ESUS are 1) with EHV low.
PGM can be cleared by the user only when PSUS and EHV are low and DONE is high. PGM is cleared on reset.
0 Flash is not executing a program sequence.
1 Flash is executing a program sequence.
Note: In an erase-suspended program, programming Flash locations in blocks which were being operated on in the
erase may corrupt FC data. This should be avoided due to reliability implications.
PSUS
Program Suspend. PSUS is used to indicate the flash module is in program suspend or in the process of entering
a suspend state. The module is in program suspend when PSUS = 1 and DONE = 1. PSUS can be set high only
when PGM and EHV are high. A 0 to 1 transition of PSUS starts the sequence which sets DONE and places the
flash module in program suspend.
PSUS can be cleared only when DONE and EHV are high. A 1 to 0 transition of PSUS with EHV = 1 starts the
sequence which clears DONE and returns the flash module to program. The module cannot exit program suspend
and clear DONE while EHV is low. PSUS is cleared on reset.
0 Program sequence is not suspended.
1 Program sequence is suspended.
ERS
Erase. ERS is used to set up flash for an erase operation. A 0 to 1 transition of ERS initiates an erase sequence. A
1 to 0 transition of ERS ends the erase sequence. ERS can only be set only in user mode read (PGM is low and
UTE is 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.
Freescale Semiconductor
PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
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