Freescale Semiconductor MK22FN256VDC12, Reference Manual

Page: 638 / 1313

Table 29-45. Flash Commands by Mode
FCMD Command
NVM Normal NVM Special
Unsecure Secure MEEN=10 Unsecure Secure MEEN=10
0x01 Read 1s Section × × × × — —
0x02 Program Check × × × × — —
0x03 Read Resource × × × × — —
0x06 Program Longword × × × × — —
0x09 Erase Flash Sector × × × × — —
0x40 Read 1s All Blocks × × × × × —
0x41 Read Once × × × × — —
0x43 Program Once × × × × — —
0x44 Erase All Blocks × × × × × —
0x45
Verify Backdoor Access
Key
× × × × — —
29.4.10 Margin Read Commands
The Read-1s commands (Read 1s All Blocks 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 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.
The 'user' and 'factory' levels become, in effect, a minimum safety margin; i.e. if the reads
pass at the tighter tolerances of the 'user' and 'factory' margins, then the 'normal' reads
have at least this much safety margin before they experience data loss.
Functional Description
K22F Sub-Family Reference Manual , Rev. 3, 7/2014
638 Freescale Semiconductor, Inc.