Flash Memory
265
Mitsubishi microcomputers
M16C / 62P Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
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
Operation mode
EW0 mode
EW1 mode
Single chip mode
Memory expansion mode
Boot mode
User ROM area
Boot ROM area
Single chip mode
Areas in which a
rewrite control
program can be located
Areas in which a
rewrite control
program can be executed before being executed
Areas which can be
rewritten
User ROM area
Must be transferred to any area other Can be executed directly in the user
than the flash memory (e.g., RAM)
ROM area
User ROM area
User ROM area
However, this does not include the area
in which a rewrite control program
exists
Program, Block Erase command
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
Read Array mode
Software command
limitations
None
Modes after Program or
Erase
CPU status during Auto
Write and Auto Erase
Read Status Register mode
Operating
Hold state (I/O ports retain the state in
which they were before the command
was executed)
(Note)
Read the FMR0 register's FMR00,
FMR06, and FMR07 bits in a program
Flash memory status
detection
Read the FMR0 register's FMR00,
FMR06, and FMR07 bits in a
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.