Flash Memory
MPC5565 Microcontroller Reference Manual, Rev. 1.0
Freescale Semiconductor
13-11
Figure 13-5. PEG Valid Times
13.3.2.1.1
MCR Simultaneous Register Writes
A number of MCR bits are protected against write when another bit or set of bits is in a specific state. These
write locks are covered on a bit by bit basis in
Section 13.3.2.1, “Module Configuration Register
.” The write locks detailed in that section do not consider the effects of trying to write two
or more bits simultaneously. The effects of writing bits simultaneously which would put the flash module
in an illegal state are detailed here.
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 can 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 can be written during suspend. EHV must be high for the
flash to exit suspend. Do not writer the EHV bit after a suspend bit is set high and before DONE has
transitioned high. Do not set the EHV bit 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 can
corrupt flash core data. Avoid this case due to reliability implications.
2
Aborting a high voltage operation leaves the flash core addresses in an indeterminate data state. This can be recovered
by executing an erase on the affected blocks.
Table 13-5. FLASH_MCR Field Descriptions (continued)
Field
Description
FLASH_MCR[PGM/ERS]
FLASH_MCR[EHV]
FLASH_MCR[DONE]
FLASH_MCR[PEG]
PEG
valid
PEG
valid
PEG
valid
Abort
Program/erase
Summary of Contents for MPC5565
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