Information

Table 28-32. Allowed Simultaneous Memory Operations
Program Flash Data Flash FlexRAM
Read Program
Sector
Erase
Read Program
Sector
Erase
Read E-Write
1
R-Write
2
Program
flash
Read — OK OK OK
Program — OK OK OK
3
Sector
Erase
— OK OK OK
Data
flash
Read OK OK —
Program OK — OK OK
Sector
Erase
OK — OK OK
FlexRAM
Read OK OK OK OK —
E-Write
1
OK —
R-Write
2
OK OK OK OK —
1. When FlexRAM configured for EEPROM (writes are effectively multi-cycle operations).
2. When FlexRAM configured as traditional RAM (writes are single-cycle operations).
3. When FlexRAM configured as traditional RAM, writes to the RAM are ignored while the Program Section command is
active (CCIF = 0).
28.4.10 Margin Read Commands
The Read-1s commands (Read 1s All Blocks, Read 1s Block, and Read 1s Section) and
the Program Check command have a margin choice parameter that allows the user to
apply non-standard read reference levels to the program flash and data flash array reads
performed by these commands. Using the preset 'user' and 'factory' margin levels, these
commands perform their associated read operations at tighter tolerances than a 'normal'
read. These non-standard read levels are applied only during the command execution. All
simple (uncommanded) flash array reads to the MCU always use the standard, un-
margined, read reference level.
Only the 'normal' read level should be employed during normal flash usage. The non-
standard, 'user' and 'factory' margin levels should be employed only in special cases.
They can be used during special diagnostic routines to gain confidence that the device is
not suffering from the end-of-life data loss customary of flash memory devices.
Erased ('1') and programmed ('0') bit states can degrade due to elapsed time and data
cycling (number of times a bit is erased and re-programmed). The lifetime of the erased
states is relative to the last erase operation. The lifetime of the programmed states is
measured from the last program time.
Chapter 28 Flash Memory Module (FTFL)
K20 Sub-Family Reference Manual, Rev. 2, Feb 2012
Freescale Semiconductor, Inc. 533