Datasheet

Section 17 ROM
Rev.7.00 Feb. 14, 2007 page 701 of 1108
REJ09B0089-0700
(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 Description
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'5A is in software
protection state.)
H'00 Initial value