Cpu Rewrite Mode - Renesas M16C/60 Series Hardware Manual

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M16C/6N5 Group

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 1.22.1 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 1.22.3 lists the differences between EW0 and EW1 modes.
Table 1.22.3 EW0 Mode and EW1 Mode
Item
Operation mode
Areas in which a
rewrite control
program can be located
Areas in which a
rewrite control
program can be executed before being executed (Note 2)
Areas which can be
rewritten
Software command
limitations
Modes after Program or
Erase
CPU status during Auto
Write and Auto Erase
Flash memory status
detection
Note 1: Make sure no interrupts (except NMI and watchdog timer interrupts) and DMA transfers will occur.
Note 2: When in CPU rewrite mode, the PM10 and PM13 bits in the PM1 register are set to "1". The rewrite
control program can only be executed in the internal RAM or in an external area that is enabled for
use when the PM13 bit = 1.
Rev.1.00 2003.05.30 page 262
EW0 mode
• Single chip mode
• Memory expansion mode
• Boot mode
• User ROM area
• Boot ROM area
Must be transferred to any area other Can be executed directly in the user
than the flash memory (e.g., RAM)
User ROM area
None
Read Status Register mode
Operating
•Read the FMR0 register's FMR00,
FMR06, and FMR07 bits in a program FMR06, and FMR07 bits in a program
•Execute the Read Status Register
command to read the status register's
SR7, SR5, and SR4 flags.
_______
EW1 mode
Single chip mode
User ROM area
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
Hold state (I/O ports retain the state in
which they were before the command
was executed) (Note 1)
Read the FMR0 register's FMR00,
Flash Memory