
R8C/14 Group, R8C/15 Group 18. Flash Memory Version
Rev.2.10 Jan 19, 2006 Page 197 of 253
REJ09B0164-0210
18.4 CPU Rewrite Mode
In CPU rewrite mode, 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 a board
without using such as a ROM programmer. Execute the program and block erase commands only to
each block in user ROM area.
When an interrupt request is generated during an erase operation in CPU rewrite mode, the flash
module contains an erase-suspend function which performs the interrupt process after the erase
operation is halted temporarily. During the erase-suspend, user ROM area can be read by a program.
CPU rewrite mode contains erase write 0 mode(EW0 mode) and erase write 1 mode(EW1 mode). Table
18.3 lists the Differences between EW0 Mode and EW1 Mode.
NOTES:
1. When setting the FMR02 bit in the FMR0 register to “1” (rewrite enables) and rewriting Block 0 is
enabled by setting the FMR15 bit in the FMR1 register to “0” (rewrite enables). Rewriting Block 1 is
enabled by setting the FMR16 bit to “0” (rewrite enables).
Table 18.3 Differences between EW0 Mode and EW1 Mode
Item EW0 Mode EW1 Mode
Operating Mode Single chip mode Single chip mode
Area in which rewrite
control program can be
located
User ROM area User ROM area
Area in which rewrite
control program can be
executed
Necessary to transfer to any areas
other than the flash memory (e.g.,
RAM) before executing
Executing directly on user ROM area
is possible
Area which can be
rewritten
User ROM area User ROM area
However, other than the blocks
which contain a rewrite control
program
(1)
Software Command
Restriction
None • Program, block erase command
Disable to execute on any block
which contains a rewrite control
program
• Disables to execute the read status
register command
Mode after Program or
Erase
Read status register mode Read array mode
CPU Status during Auto-
Write and Auto-Erase
Operating Hold state (I/O ports hold state
before the command is executed)
Flash Memory Status
Detection
• Read the FMR00, FMR06, and
FMR07 bits in the FMR0 register by
a program
• Execute the read status register
command and read the SR7, SR5,
and SR4 bits in the status register.
Read the FMR00, FMR06, and
FMR07 bits in the FMR0 register by a
program
Condition for Transition to
Erase-Suspend
Set the FMR40 and FMR41 bits in
the FMR4 register to “1” by a
program.
The FMR40 bit in the FMR4 register
is set to “1” and the interrupt request
of the enabled maskable interrupt is
generated
CPU Clock 5MHz or below No restriction to the following (clock
frequency to be used)
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