Technical information

AN2216/D

Appendix A: Flash Memory Protection

MOTOROLA MC9S12DP256 Software Development Using Metrowerk’s Codewarrior 21

Figure 20. Flash Protection and Security Memory Locations

The FPHDIS and FPLDIS bits determine the protection state of the upper and

lower areas within each 64K block respectively. The erased state of these bits

allows erasure and programming of the two protected areas and renders the

state of the FPHS[1:0] and FPLS[1:0] bits immaterial. When either of these bits

is programmed, the FPHS[1:0] and FPLS[1:0] bits determine the size of the

upper and lower protected areas. The tables in Figure 21 summarize the

combinations of the FPHS[1:0] and FPLS[1:0] bits and the size of the protected

area selected by each.

Figure 21. Flash Protection Select Bits

Trying to program or erase any of the protected areas will result in a protection

violation error and bit PVIOL will be set in the Flash Status Register FSTAT.

NOTE: A mass or bulk erase of the full 64K byte block is only possible when the

FPLDIS and FPHDIS bits are in the erased state.

Address

$FF00 - $FF07

Description

Security Backdoor Comparison Key

Reserved

$FF08 - $FF09

$FF0A

$FF0B

$FF0C

$FF0E

$FF0D

$FF0F

Protection Byte For Flash Block 3

Protection Byte For Flash Block 2

Protection Byte For Flash Block 1

Protection Byte For Flash Block 0

Reserved

Security Byte

FPHS[1:0] Protected Size FPLS[1:0] Protected Size

0:0

0:1

1:0

1:1

0:0

0:1

1:0

1:1

16K

512 Bytes