Flash Array and Control
MPC5510 Microcontroller Family Reference Manual, Rev. 1
Freescale Semiconductor
22-25
Preliminary
Figure 22-13. Erase Sequence
22.5.6
Flash
Shadow Block
The flash shadow block is a memory-mapped block in the flash memory map. Program and erase of the
shadow block are enabled when MCR[PEAS] = 1 only. After the user has begun an erase operation on the
shadow block, the operation cannot be suspended to program the main address space and vice-versa. The
user must terminate the shadow erase operation to program or erase the main address space.
User mode read state
Write MCR
ERS = 1
Select blocks
Erase interlock write
Step 1
Step 2
Step 3
Write MCR
EHV = 1
High voltage active
Access MCR
DONE
?
Step 4
WRITE
ESUS = 1
Read MCR
DONE = 1
Erase suspend
ERS = 0
User mode read state
PEG = 0
Read MCR
DONE = 1
DONE = 0
Write MCR
ESUS = 0
EHV = 1
Abort
WRITE
EHV = 0
Step 5
Step 6
PEG
?
Success
PEG = 1
Write MCR
Failure
PEG = 0
Step 7
EHV = 0
Erase
more blocks
Step 8
?
No
Yes
Write MCR
ERS = 0
User mode read state
Step 9
EHV = 0
Write MCR
PGM = 1
Program,
Step 2
Go to
Step 2
Note: PEG will remain valid under this
condition until EHV is set high or
ERS is cleared.
Note: ESUS cannot be cleared while
EHV = 0. ESUS and EHV cannot
be changed in a single
write operation.
PEG Valid Period