HD64F2168 Datasheet, PDF (665/874 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer

• 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.
Initial
Bit
Bit Name Value R/W Description
7
K7
0
6
K6
0
5
K5
0
4
K4
0
3
K3
0
2
K2
0
1
K1
0
0
K0
0
R/W Key Code
R/W
Only when H'A5 is written, writing to the SCO bit is valid.
R/W
When the value other than H'A5 is written to FKEY, 1
R/W
cannot be set to the SCO bit. Therefore downloading to
R/W
the on-chip RAM cannot be executed.
R/W
R/W
Only when H'5A is written, programming/erasing can be
R/W
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
Rev. 3.00, 03/04, page 625 of 830