Information

After clearing CCIF to launch the Read 1s All Blocks command, the FTFL :
• sets the read margin for 1s according to Table 28-48,
• checks the contents of the program flash are in the erased state.
If the FTFL confirms that these memory resources are erased, security is released by
setting the FSEC[SEC] field to the unsecure state. The security byte in the flash
configuration field (see Flash Configuration Field Description) remains unaffected by the
Read 1s All Blocks command. If the read fails, i.e. all memory resources are not in the
fully erased state, the FSTAT[MGSTAT0] bit is set.
The EEERDY and RAMRDY bits are clear during the Read 1s All Blocks operation and
are restored at the end of the Read 1s All Blocks operation.
The CCIF flag sets after the Read 1s All Blocks operation has completed.
Table 28-48. Margin Level Choices for Read 1s All Blocks
Read Margin Choice Margin Level Description
0x00 Use the 'normal' read level for 1s
0x01 Apply the 'User' margin to the normal read-1 level
0x02 Apply the 'Factory' margin to the normal read-1 level
Table 28-49. Read 1s All Blocks Command Error Handling
Error Condition Error Bit
An invalid margin choice is specified FSTAT[ACCERR]
Read-1s fails FSTAT[MGSTAT0]
28.4.10.10 Read Once Command
The Read Once command provides read access to a reserved 64-byte field located in the
program flash 0 IFR (see Program Flash IFR Map and Program Once Field). Access to
this field is via 16 records, each 4 bytes long. The Read Once field is programmed using
the Program Once command described in Program Once Command.
Table 28-50. Read Once Command FCCOB Requirements
FCCOB Number FCCOB Contents [7:0]
0 0x41 (RDONCE)
1 Read Once record index (0x00 - 0x0F)
2 Not used
3 Not used
Table continues on the next page...
Flash Operation in Low-Power Modes
K20 Sub-Family Reference Manual, Rev. 6, Nov 2011
638 Freescale Semiconductor, Inc.