R01UH0092EJ0110 Rev.1.10
Page 96 of 807
Jul 31, 2012
M16C/64C Group
8. Clock Generator
8.2.8
Processor Mode Register 2 (PM2)
Set the PRC1 bit in the PRCR register to 1 (write enabled) before rewriting this register.
PM21 (System clock protection bit) (b1)
The PM21 bit is used to protect the CPU clock. (Refer to 8.6 “System Clock Protection Function”).
When the PM21 bit is set to 1, writing to the following bits has no effect:
•
Bits CM02, CM05, and CM07 in the CM0 register
•
Bits CM10 and CM11 in the CM1 register
•
The CM20 bit in the CM2 register
•
All bits in the PLC0 register
Do not execute the WAIT instruction when the PM21 bit is 1.
Once the PM21 bit is set to 1, it cannot be set to 0 by a program (writing 0 has no effect).
PM25 (Peripheral clock fC provide bit) (b5)
The PM25 bit provides fC to the real-time clock, CEC function, and remote control signal receiver. (See
Figure 8.5 “Peripheral Function Clocks”.)
b7
1
0
b6 b5 b4
b1
b2
b3
Processor Mode Register 2
Symbol
PM2
Address
001Eh
Bit Symbol
Bit Name
RW
—
(b0)
Reset Value
XX00 0X01b
b0
Function
Reserved bit
—
(b2)
—
(b3)
Set to 1.
PM24
PM25
Set to 0
0 : NMI interrupt disabled
1 : NMI interrupt enabled
Reserved bit
NMI interrupt enable bit
RW
RW
RW
PM21
System clock protection bit
0 : Clock is protected by PRCR register
1 : Clock change disabled
RW
RW
No register bit. If necessary, set to 0. The read value is undefined.
—
—
(b7-b6)
No register bits. If necessary, set to 0. The read value is undefined.
—
0 : Not provided
1 : Provided
Peripheral clock fC provide bit
Содержание M16C Series
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