upd70f3422gj-gae-qs-ax Renesas Electronics Corporation., upd70f3422gj-gae-qs-ax Datasheet - Page 164

• Manufacturer Part Number: upd70f3422gj-gae-qs-ax
• Description: 32-bit Single-chip Microcontroller
• Manufacturer: Renesas Electronics Corporation.

Chapter 4
164
Initial Value
Address
Caution
Access
(2)
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.
This register can only be written in 8-bit units.
FFFF FCB0
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.
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.
Preliminary User’s Manual U17566EE1V2UM00
W
X
7
H
W
6
X
W
X
5
W
X
4
W
X
3
W
2
X
Clock Generator
W
X
1
W
X
0