Filter
Top Products
MCF51QE128 MCU Series Reference Manual, Rev. 3
74 Freescale Semiconductor
Get the latest version from freescale.com
Chapter 4 Memory
4.4.2.4 Flash Protection Register (FPROT and NVPROT)
The FPROT register defines which flash sectors are protected against program or erase operations. FPROT
bits are readable and writable as long as the size of the protected flash memory is being increased. Any
write to FPROT that attempts to decrease the size of the protected flash memory is ignored.
During the reset sequence, the FPROT register is loaded from the flash protection byte in the flash
configuration field (see Section 4.2.1), indicated by F in Table 4-6. To change the flash protection loaded
during the reset sequence, the flash sector containing the flash configuration field must be unprotected.
Then, the flash protection byte must be reprogrammed.
Trying to alter data in any protected area in the flash memory results in a protection violation error and
FSTAT[FPVIOL] is set. The mass erase of the flash array is not possible if any of the flash sectors
contained in the flash array are protected.
Table 4-11. FCNFG Field Descriptions
Field Description
7–6 Reserved, should be cleared.
5
KEYACC
Enable Security Key Writing
0 Writes to the flash block are interpreted as the start of a command write sequence.
1 Writes to the flash block are interpreted as keys to open the backdoor.
4–0 Reserved, should be cleared.
76543210
R
FPS FPOPEN
W
ResetFFFFFFFF
Figure 4-6. Flash Protection Register (FPROT)
Table 4-12. FPROT Field Descriptions
Field Description
7–1
FPS
Flash Protection Size. With FPOPEN set, the FPS bits determine the size of the protected flash address range
as shown in Table 4- 13.
0
FPOPEN
Flash Protection Open
0 Flash array fully protected.
1 Flash array protected address range determined by FPS bits.
Table 4-13. Flash Protection Address Range
FPS FPOPEN
Protected Address Range
Relative to Flash Array Base
Protected
Size
— 0 0x0_0000–0x1_FFFF 128 Kbytes