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Chapter 4
Clock Generator
Preliminary User’s Manual U17566EE1V2UM00
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PRCMDCMM - CLMM write protection register
The 8-bit PRCMDCMM register protects the register CLMM from inadvertent
write access, so that the system does not stop in case of a program hang-up.
After data has been written to the PRCMDCMM register, the first write access
to register CLMM is valid. All subsequent write accesses are ignored. Thus,
the value of CLMM can only be rewritten in a specified sequence, and illegal
write access is inhibited.
Access
This register can only be written in 8-bit units.
Address
FFFF FCB0
H
Initial Value
The contents of this register is undefined.
After writing to the PRCMDCMM register, you are permitted to write once to
CLMM. The write access to CLMM must happen with the immediately following
instruction.
Caution
In case a high level programming language is used, make sure that the
compiler translates the two write instructions to PRCMDCMM and CLMM into
two consecutive assembler “store” instructions.
7
6
5
4
3
2
1
0
X
X
X
X
X
X
X
X
W
W
W
W
W
W
W
W
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