Chapter 27 Functional Safety
MPC5602P Microcontroller Reference Manual, Rev. 4
Freescale Semiconductor
751
When writing to address 0x2008 the registers MR9 and MR8 in the protected module are updated. The
corresponding lock bits SLBR2.SLB[1:0] are set while the lock bits SLBR2.SLB[3:2] remain unchanged
(right part of
shows an example where some addresses are protected and some are not.
Figure 27-10. Enable locking for protected and unprotected addresses
, addresses 0x0C and 0x0D are unprotected. Therefore their corresponding
lock bits SLBR3.SLB[1:0] are always 0b0 (shown in bold). When doing a 32-bit write access to address
0x200C only lock bits SLBR3.SLB[3:2] are set while bits SLBR3.SLB[1:0] stay 0b0.
NOTE
Lock bits can only be set via writes to the mirror module space. Reads from
the mirror module space will not change the lock bits.
27.2.6.2.3
Write protection for locking bits
Changing the locking bits through any of the procedures mentioned in
Section 27.2.6.2.1, “Change lock
settings directly via area #4,
and
Section 27.2.6.2.2, “Enable locking via mirror module space (area #3)
is
only possible as long as the GCR[HLB] bit is cleared. Once this bit is set the locking bits can no longer be
modified until there was a system reset.
27.2.6.3
Access errors
The protection module generates transfer errors under several circumstances. For the area definition refer
to
1. If accessing area #1 or area #3, the protection module will pass on any access error from the
underlying Module under Protection.
2. If user mode is not allowed, user writes to all areas will assert a transfer error and the writes will
be blocked.
3. If accessing the reserved area #2, a transfer error will be asserted.
4. If accessing unimplemented 32-bit registers in area #4 and area #5 a transfer error will be asserted.
5. If writing to a register in area #1 and area #3 with Soft Lock Bit set for any of the affected bytes a
transfer error is asserted and the write will be blocked. Also the complete write operation to
non-protected bytes in this word is ignored.
6. If writing to a Soft Lock Register in area #4 with the Hard Lock Bit being set a transfer error is
asserted.
SLBR
3
WE[3:0]
0 0 0 0
0 0
0 0
SLB[3:0]
Before write access
SLBR
3
WE[3:0]
0 0 0 0
0 0
1 1
SLB[3:0]
32-bit write to address 0x200C
set lock bits
write to
MR[15:12]
After
write access