Flash Array and Control
MPC5510 Microcontroller Family Reference Manual, Rev. 1
22-8
Freescale Semiconductor
Preliminary
28
PSUS
Program Suspend. Indicates the flash module is in program suspend or in the process of entering a suspend
state. The flash 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
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 flash 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
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ERS
Erase. Used to set up flash for an erase operation. A 0 to 1 transition of ERS initiates an flash erase sequence.
A 1 to 0 transition of ERS ends the erase sequence. ERS can be set in a normal operating mode read only (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 that 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 22-3. MCR Field Descriptions (continued)
Field
Description