R01UH0823EJ0100 Rev.1.00 Page 1681 of 1823
Jul 31, 2019
RX23W Group 50. Flash Memory (FLASH)
50.5 Start-Up Program Protection
When rewriting the start-up program*
1
by self-programming, if the rewrite operation is interrupted due to temporary
blackout, the start-up program may not be successfully programmed and the user program may not start properly.
This problem can be avoided by rewriting the start-up program without erasing the existing start-up program using the
start-up program protection. This function is available in products with a 32-Kbyte or larger ROM.
Figure 50.4 shows the Overview of the Start-Up Program Protection. In this figure, the default area indicates block 0 to
block 7, and the alternate area indicates block 8 to block 15.
Note 1. Program to perform operation to start the user program. It includes the fixed vector table.
Figure 50.4 Overview of the Start-Up Program Protection
FFFE 0000h
User program
Before rewriting
No program
(alternate area)
Original start-up
program
(default area)
FFFF 8000h
FFFF C000h
FFFF FFFFh
User program
New start-up
program
(alternate area)
Original start-up
program
(default area)
User program
New start-up
program
(alternate area)
Original start-up
program
(default area)
(1) Program a new start-up program in the alternate area. If the alternate area fails to be rewritten, the new start-up
program can be rewritten again after starting up using the default area, because the original start-up program is
in the default area.
(2) After the alternate area is successfully rewritten, the default area and the alternate area are switched using the
start-up area information program command. After that, the program in the alternate area starts after a reset.
(1) (2)Address
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