M30240ECFP MITSUBISHI [Mitsubishi Electric Semiconductor], M30240ECFP Datasheet - Page 28

• Manufacturer Part Number: M30240ECFP
• Description: M30240 Group Specification
• Manufacturer: MITSUBISHI [Mitsubishi Electric Semiconductor]

2.13 Protection
Figure 1.14: Protect register
Specifications in this manual are tentative and subject to change
Protection
The protection function is provided so that the values in important registers cannot be changed in the
event that the program runs out of control. Figure 1.14 shows the protect register. The values in the
processor mode register 0 (address 0004
control register 0 (address 0006
synthesizer registers can only be changed when the respective bit in the protect register is set to “1”.
The system clock control registers 0 and 1 write-enable bit (bit 0 at 000A
0 and 1 write-enable bit (bit 1 at 000A
to an address. The program must therefore be written to return these bits to “0”.
Protect register
b7
b6
b5
b4
b3
b2
b1
b0
Bit symbol
Nothing is assigned.
These bits can neither be set nor reset. When read, their contents are
indeterminate.
Reserved bit
PRC0
PRC1
Symbol
PRCR
16
), system clock control register 1 (address 0007
16
) do not automatically return to “0” after a value has been written
Enables writing to system clock
control registers 0 and 1 (addresses
0006
synthesizer registers (addresses
03DB
Enables writing to processor mode
registers 0 and 1 (addresses 0004
and 0005
16
), processor mode register 1 (address 0005
16
16
and 0007
to 03DF
16
1-28
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
)
Address
000A
Bit name
16
16
)
) and frequency
16
XXXXX000
When reset
16
0 : Write-inhibited
1 : Write-enabled
Must always be set to "0"
2
0 : Write-inhibited
1 : Write-enabled
16
) and processor mode register
Function
Mitsubishi microcomputers
M30240 Group
16
16
) and frequency
), system clock
R
W