Datasheet

Chapter 4 Memory
MC9S08EL32 Series and MC9S08SL16 Series Data Sheet, Rev. 3
Freescale Semiconductor 59
4.5.11.4 FLASH and EEPROM Protection Register (FPROT and NVPROT)
FPROT register defines which FLASH and EEPROM sectors are protected against program and erase
operations.
During the reset sequence, the FPROT register is loaded from the nonvolatile location NVPROT. To
change the protection that will be loaded during the reset sequence, the sector containing NVPROT must
be unprotected and erased, then NVPROT can be reprogrammed.
FPROT bits are readable at any time and writable as long as the size of the protected region is being
increased. Any write to FPROT that attempts to decrease the size of the protected region will be ignored.
Trying to alter data in any protected area will result in a protection violation error and the FPVIOL flag
will be set in the FSTAT register. Mass erase is not possible if any one of the sectors is protected.
Figure 4-8. FLASH and EEPROM Protection Register (FPROT)
76543210
R
EPS FPS FPOP
W
ResetFFFFFFFF
Table 4-11. FPROT Register Field Descriptions
Field Description
7:6
EPS
EEPROM Protect Select Bits — This 2-bit field determines the protected EEPROM locations that cannot be
erased or programmed. See Tabl e 4 - 12 .
5:1
FPS
FLASH Protect Select Bits — This 5-bit field determines the protected FLASH locations that cannot be erased
or programmed. See Tabl e 4 - 13 .
0
FPOP
FLASH Protect Open Bit — This bit determines the protected FLASH locations that cannot be erased or
programmed. See Tabl e 4 - 13 .
Table 4-12. EEPROM Block Protection
EPS
Address Area
Protected
Memory Size
Protected (bytes)
Number of Sectors
Protected
0x3 N/A 0 0
0x2
0x17F8 - 0x17FF 16 2
0x1
0x17F0 - 0x17FF 32 4
0x0
0x17E0–0x17FF 64 8