Datasheet

RL78/L12 CHAPTER 26 FLASH MEMORY
R01UH0330EJ0200 Rev.2.00 822
Dec 13, 2013
26.6.2 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 26-9. Flash Shield Window Setting Example
(Target Devices: R5F100LE, 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 26-11. Relationship between Flash Shield Window Function Setting/Change Methods and Commands
Programming conditions
Window Range
Setting/Change Methods
Execution Commands
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 26.7 Security Settings to prohibit writing/erasing during serial programming.