M306V0ME Mitsubishi, M306V0ME Datasheet - Page 46

• Manufacturer Part Number: M306V0ME
• Description: SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER and ON-SCREEN DISPLAY CONTROLLER
• Manufacturer: Mitsubishi

46
2.6 Protection
Figure 2.6.1 Protect register
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 2.6.1 shows the protect register. The values in the processor
mode register 0 (address 0004
ister 0 (address 0006
(address 03F3
fore, important outputs can be allocated to port P9.
If, after “1” (write-enabled) has been written to the port P9 direction register write-enable bit (bit 2 at address
000A
system clock control registers 0 and 1 write-enable bit (bit 0 at 000A
1 write-enable bit (bit 1 at 000A
address. The program must therefore be written to return these bits to “0”.
16
), a value is written to any address, the bit automatically reverts to “0” (write-inhibited). However, the
Protect register
b7
b6
16
b5
) can only be changed when the respective bit in the protect register is set to “1”. There-
b4
b3
16
), system clock control register 1 (address 0007
b2
b1
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
b0
16
Note: Writing a value to an address after “1” is written to this bit returns the bit
16
Bit symbol
Nothing is assigned.
In an attempt to write to these bits, write “0.” The value, if read, turns out to be
indeterminate.
), processor mode register 1 (address 0005
) do not automatically return to “0” after a value has been written to an
PRC0
PRC1
PRC2
Symbol
PRCR
to “0.” Other bits do not automatically return to “0” and they must therefore
be reset by the program.
Enables writing to system clock
control registers 0 and 1 (addresses
0006
Enables writing to processor mode
registers 0 and 1 (addresses 0004
and 0005
Enables writing to port P9 direction
register (address 03F3
(Note
16
)
and 0007
16
)
Address
000A
Bit name
16
)
16
16
)
XXXXX000
When reset
16
16
and ON-SCREEN DISPLAY CONTROLLER
) and processor mode register 0 and
0 : Write-inhibited
1 : Write-enabled
0 : Write-inhibited
1 : Write-enabled
0 : Write-inhibited
1 : Write-enabled
2
16
MITSUBISHI MICROCOMPUTERS
) and port P9 direction register
16
M306V0ME-XXXFP
Function
), system clock control reg-
M306V0EEFP
R
W
Rev. 1.0