165
Clock Generator
Chapter 4
Preliminary User’s Manual U17566EE1V2UM00
(3)
CLMS - Sub oscillator clock monitor register
The 8-bit CLMS register is used to enable the monitor for the sub oscillator
clock.
Access
This register can be read/written in 8-bit or 1-bit units.
Writing to this register is protected by a special sequence of instructions.
Please refer to
“PRCMDCMS - CLMS write protection register” on page 165
for details.
Address
FFFF F878
H
.
Initial Value
00
H
. The register is initialized by any reset.
Note
Setting CLMS.CLMES to 1 does not start the sub oscillator clock monitor. To
start the clock monitor CLMCS.CMRT has to be set to 1 afterwards.
CLMCS.CMRT must not be set before the sub oscillator has stabilized.
(4)
PRCMDCMS - CLMS write protection register
The 8-bit PRCMDCMS register protects the register CLMS 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 PRCMDCMS register, the first write access
to register CLMS is valid. All subsequent write accesses are ignored. Thus, the
value of CLMS 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 FCB2
H
Initial Value
The contents of this register is undefined.
After writing to the PRCMDCMS register, you are permitted to write once to
CLMS. The write access to CLMS 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 PRCMDCMS and CLMS into
two consecutive assembler “store” instructions.
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
CLMES
R
R
R
R
R
R
R
R/W
Table 4-22
CLMS register contents
Bit position
Bit name
Function
0
CLMES
Clock monitor enable:
0: Clock monitor
for
sub oscillator disabled.
1: Clock monitor for sub oscillator enabled.
This bit can only be cleared by reset.
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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