Renesas H8SX/1520 Series Hardware Manual page 621

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Flash Key Code Register (FKEY)
FKEY is a register for software protection that enables to download the on-chip program and
perform programming/erasing of the flash memory.
Bit
Bit Name
Initial Value
R/W
Bit Bit Name
7 K7
6 K6
5 K5
4 K4
3 K3
2 K2
1 K1
0 K0
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7 6 5
K7 K6 K5
0 0 0
R/W R/W R/W
Initial
Value R/W
0 R/W
0 R/W
0 R/W
0 R/W
0 R/W
0 R/W
0 R/W
0 R/W
Section 17 Flash Memory (0.18-(m F-ZTAT Version)
4 3
K4 K3
0 0
R/W R/W
Description
Key Code
When H'A5 is written to FKEY, writing to the SCO bit in
FCCS is enabled. When a value other than H'A5 is
written, the SCO bit cannot be set to 1. Therefore, the
on-chip program cannot be downloaded to the on-chip
RAM.
Only when H'5A is written can programming/erasing of
the flash memory be executed. When a value other than
H'5A is written, even if the programming/erasing
program is executed, programming/erasing cannot be
performed.
H'A5: Writing to the SCO bit is enabled. (The SCO bit
cannot be set to 1 when FKEY is a value other
than H'A5.)
H'5A: Programming/erasing of the flash memory is
enabled. (When FKEY is a value other than
H'5A, the software protection state is entered.)
H'00: Initial value
Rev. 3.00 Mar. 14, 2006 Page 583 of 804
2 1 0
K2 K1 K0
0 0 0
R/W R/W R/W
REJ09B0104-0300