NXP Semiconductors K22F series, Reference Manual, Page: 644 / 1407

FTFA_FPROTn field descriptions (continued)
Field Description
Each bit in the 32-bit protection register represents 1/32 of the total program flash except for memory
configurations with less than 64 KB of program flash where each assigned bit protects 2 KB .
0 Program flash region is protected.
1 Program flash region is not protected
29.3.3.7 Execute-only Access Registers (FTFA_XACCn)
The XACC registers define which program flash segments are restricted to data read or
execute only or both data and instruction fetches.
The eight XACC registers allow up to 64 restricted segments of equal memory size.
Execute-only access register Program flash execute-only access bits
XACCH0 XA[63:56]
XACCH1 XA[55:48]
XACCH2 XA[47:40]
XACCH3 XA[39:32]
XACCL0 XA[31:24]
XACCL1 XA[23:16]
XACCL2 XA[15:8]
XACCL3 XA[7:0]
During the reset sequence, the XACC registers are loaded with the logical AND of
Program Flash IFR addresses A and B as indicated in the following table.
Execute-only access register Program Flash IFR address A Program Flash IFR address B
XACCH0 0xA3 0xAB
XACCH1 0xA2 0xAA
XACCH2 0xA1 0xA9
XACCH3 0xA0 0xA8
XACCL0 0xA7 0xAF
XACCL1 0xA6 0xAE
XACCL2 0xA5 0xAD
XACCL3 0xA4 0xAC
Use the Program Once command to program the execute-only access control fields that
are loaded during the reset sequence.
Memory Map and Registers
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
644 NXP Semiconductors