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RL78/G1A CHAPTER 25 FLASH MEMORY
25.6.3 Flash shield window function
The flash shield window function is provided as one of the security functions for self-programming. It disables writing to
and erasing areas outside the range specified as a window only during self-programming.
The window range can be set by specifying the start and end blocks. The window range can be set or changed during
both serial programming and self-programming.
Writing to and erasing areas outside the window range are disabled during self-programming. During serial
programming, however, areas outside the range specified as a window can be written and erased.
Figure 25-11. Flash Shield Window Setting Example
(Target Devices: R5F10ELE, Start Block: 04H, End Block: 06H)
Block
00H
Block
01H
Block
02H
Block
03H
Block
05H
Block
06H
(end block)
Block
04H
(start block)
Block
3FH
Block
3EH
√: Serial programming
×: Self-programming
√: Serial programming
√: Self-programming
√: Serial programming
×: Self-programming
Flash memory
area
Flash shield
range
Methods by which writing can be performed
Window range
Flash shield
range
0FFFFH
01C00H
01BFFH
01000H
00FFFH
00000H
Cautions 1. If the rewrite-prohibited area of the boot cluster 0 overlaps with the flash shield window range,
prohibition to rewrite the boot cluster 0 takes priority.
2. The flash shield window can only be used for the code flash memory (and is not supported for
the data flash memory).
Table 25-11. Relationship Between Flash Shield Window Function Setting/Change Methods and Commands
Execution Commands Programming Conditions
Window Range
Setting/Change Methods
Block Erase Write
Self-programming
Specify the starting and
ending blocks by the
flash self-programming
library.
Block erasing is enabled
only within the window
range.
Writing is enabled only
within the range of
window range.
Serial programming
Specify the starting and
ending blocks on GUI of
dedicated flash memory
programmer, etc.
Block erasing is enabled
also outside the window
range.
Writing is enabled also
outside the window
range.
Remark See 25.7 Security Settings to prohibit writing/erasing during serial programming.
R01UH0305EJ0200 Rev.2.00 819
Jul 04, 2013