D12320VF25V Datasheet, PDF (735/1146 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 17 ROM
(4) 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
:
7
6
5
4
3
2
1
0
K7
K6
K5
K4
K3
K2
K1
K0
Initial value :
0
0
0
0
0
0
0
0
R/W
: R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bits 7 to 0—Key Code (K7 to K0): 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, flash memory cannot be programmed or erased when
the value other than H'5A is written to FKEY.
Bits 7 to 0
K7 to K0
H'A5
H'5A
H'00
Description
Writing to the SCO bit is enabled (The SCO bit cannot be set by the value other
than H'A5.)
Programming/erasing is enabled (The value other than H'5A is in software
protection state.)
Initial value
Rev.7.00 Feb. 14, 2007 page 701 of 1108
REJ09B0089-0700