29.4.11.9 Read Once Command
The Read Once command provides read access to special 96-byte fields located in the
program flash 0 IFR (see Program Flash IFR Map and Program Once Field). Access to
the Program Once ID field is via 16 records (index values 0x00 - 0x0F), each 4 bytes
long. Access to the Program Once XACC and SACC fields are via 4 records (index
values 0x10 - 0x13), each of which is 8 bytes long. These fields are programmed using
the Program Once command described in Program Once Command.
Table 29-25. Read Once Command FCCOB Requirements
FCCOB Number FCCOB Contents [7:0]
0 0x41 (RDONCE)
1 Program Once record index (0x00 - 0x13)
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
8 Program Once byte 4 value (index 0x10 - 0x13)
9 Program Once byte 5 value (index 0x10 - 0x13)
10 Program Once byte 6 value (index 0x10 - 0x13)
11 Program Once byte 7 value (index 0x10 - 0x13)
After clearing CCIF to launch the Read Once command, a 4-byte or 8-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 - 0x13. 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 29-26. 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]
Chapter 29 Flash Memory Module (FTFA)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 671
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