upd78f0124hgba1-8et-a Renesas Electronics Corporation., upd78f0124hgba1-8et-a Datasheet - Page 407

• Manufacturer Part Number: upd78f0124hgba1-8et-a
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

24.8 Boot Swap Function
programming and the program in the boot area is lost, the boot swap function can execute the program correctly after
re-application of power, reset, and start.
24.8.1 Outline of boot swap function
and also set the boot flag
reset and started next time. Consequently, the above area to be swapped is used as a boot area, and the program is
executed correctly. Figure 24-21 shows an image of the boot swap function.
X X X X H
X X X X H
0 0 0 0 H
0 0 0 0 H
The 78K0/KD1+ has a boot swap function.
Even if a momentary power failure occurs for some reason while the boot area is being rewritten by self-
Before erasing the boot program area by self-programming, write a new boot program to the block to be swapped,
Note The boot flag is controlled by the flash memory control firmware of the 78K0/KD1+.
User program
User program
User program
Boot program
User program
User program
User program
Boot program
Note
. Even if a momentary power failure occurs, the address is swapped when the system is
programming
programming
Self-
Self-
X X X X H
Figure 24-21. Image of Boot Swap Function
0 0 0 0 H
X X X X H
0 0 0 0 H
(1) If boot swap is not supported
CHAPTER 24 FLASH MEMORY
(2) If boot swap is supported
Erasure in progress
New boot program
Erasure in progress
User’s Manual U16962EJ3V0UD
User program
User program
User program
User program
User program
power failure
Momentary
power failure
Momentary
X X X X H
0 0 0 0 H
X X X X H
0 0 0 0 H
New boot program
Undefined data
User program
User program
Undefined data
User program
User program
User program
Started correctly
Not restarted
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