Datasheet

Section 20 Flash Memory (0.18-μm F-ZTAT Version)
Rev.6.00 Mar. 18, 2009 Page 732 of 980
REJ09B0050-0600
• Flash Key Code Register (FKEY)
FKEY is a register for software protection that enables download of on-chip program and
programming/erasing of flash memory. Before setting the SCO bit to 1 in order to download
on-chip program or executing the downloaded programming/erasing program, these processing
cannot be executed if the key code is not written.
Bit
Bit
Name
Initial
Value R/W Description
7
6
5
4
3
2
1
0
K7
K6
K5
K4
K3
K2
K1
K0
0
0
0
0
0
0
0
0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Key Code
Only when H'A5 is written, writing to the SCO bit is valid.
When the value other than H'A5 is written to FKEY, 1
cannot be written to the SCO bit. Therefore downloading
to the on-chip RAM cannot be executed.
Only when H'5A is written, programming/erasing can be
executed. Even if the on-chip programming/erasing
program is executed, the flash memory cannot be
programmed or erased when the value other than H'5A is
written to FKEY.
H'A5: Writing to the SCO bit is enabled (The SCO bit
cannot be set by the value other than H'A5.)
H'5A: Programming/erasing is enabled (The value other
than H'A5 is in software protection state.)
H'00: Initial value