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Renesas rl78 User Manual

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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