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Flash Memory
265
Mitsubishi microcomputers
M16C / 62P Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Under
development
Preliminary Specifications Rev.1.0
Specifications in this manual are tentative and subject to change.
CPU Rewrite Mode
In CPU rewrite mode, the user ROM area can be rewritten by executing software commands from the CPU.
Therefore, the user ROM area can be rewritten directly while the microcomputer is mounted on-board
without having to use a ROM programmer, etc.
In CPU rewrite mode, only the user ROM area shown in Figure 1.27.1 can be rewritten and the boot ROM
area cannot be rewritten. Make sure the Program and the Block Erase commands are executed only on
each block in the user ROM area.
During CPU rewrite mode, the user ROM area be operated on in either Erase Write 0 (EW0) mode or Erase
Write 1 (EW1) mode. Table 1.27.3 lists the differences between Erase Write 0 (EW0) and Erase Write 1
(EW1) modes.
Table 1.27.3. EW0 Mode and EW1 Mode
Item
EW0 mode
EW1 mode
Operation mode
Single chip mode
Single chip mode
Memory expansion mode
Boot mode
Areas in which a
User ROM area
User ROM area
rewrite control
Boot ROM area
program can be located
Areas in which a
Must be transferred to any area other Can be executed directly in the user
rewrite control
than the flash memory (e.g., RAM)
ROM area
program can be executed before being executed
Areas which can be
User ROM area
rewritten
However, this does not include the area
in which a rewrite control program
exists
Software command
None
Program, Block Erase command
limitations
Cannot be executed on any block in
which a rewrite control program exists
Erase All Unlocked Block command
Cannot be executed when the lock bit
for any block in which a rewrite control
program exists is set to “1” (unlocked)
or the FMR0 register’s FMR02 bit is set
to “1” (lock bit disabled)
Read Status Register command
Cannot be executed
Modes after Program or
Read Status Register mode
Read Array mode
Erase
CPU status during Auto
Operating
Hold state (I/O ports retain the state in
Write and Auto Erase
which they were before the command
was executed)(Note)
Flash memory status
Read the FMR0 register's FMR00,
Read the FMR0 register's FMR00,
detection
FMR06, and FMR07 bits in a
FMR06, and FMR07 bits in a program
program
Execute the Read Status Register
command to read the status
register's SR7, SR5, and SR4 flags.
_______
Note: Make sure no interrupts (except NMI and watchdog timer interrupts) and DMA transfers will occur.