45.4.10.9 Read Once Command
The Read Once command provides read access to special 64-byte fields located in the
program flash 0 IFR (see
). Access to
the Program Once field is via 16 records (index values 0x00 - 0x0F), each 4 bytes long.
These fields are programmed using the Program Once command described in
.
Table 45-25. Read Once Command FCCOB Requirements
FCCOB Number
FCCOB Contents [7:0]
0
0x41 (RDONCE)
1
Program Once record index (0x00 - 0x0F)
2
Not used
3
Not used
Returned Values
4
Program Once byte 0 value
5
Program Once byte 1 value
6
Program Once byte 2 value
7
Program Once byte 3 value
After clearing CCIF to launch the Read Once command, a 4-byte Program Once record is
read and stored in the FCCOB register. The CCIF flag is set after the Read Once
operation completes. Valid record index values for the Read Once command range from
0x00 - 0x0F. During execution of the Read Once command, any attempt to read
addresses within the program flash block containing the selected record index returns
invalid data. The Read Once command can be executed any number of times.
Table 45-26. Read Once Command Error Handling
Error Condition
Error Bit
Command not available in current mode/security
FSTAT[ACCERR]
An invalid record index is supplied
FSTAT[ACCERR]
45.4.10.10 Program Once Command
The Program Once command enables programming to special 64-byte fields in the
program flash 0 IFR (see
). Access to
the Program Once field is via 16 records (index values 0x00 - 0x0F), each 4 bytes long.
These records can be read using the Read Once command (see
using the Read Resource command (see
programmed only once since the program flash 0 IFR cannot be erased.
Chapter 45 Flash Memory Module (FTFA)
KL27 Sub-Family Reference Manual , Rev. 5, 01/2016
Freescale Semiconductor, Inc.
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