UPD78F0838 Renesas Electronics Corporation., UPD78F0838 Datasheet - Page 832

• Manufacturer Part Number: UPD78F0838
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

26.11 Boot Swap Function
in the boot area may be lost and the program may not be restarted by resetting.
boot cluster 1 in advance. When the program has been correctly written to boot cluster 1, swap this boot cluster 1 and
boot cluster 0 by using the set information function of the firmware of the 78K0/Dx2, so that boot cluster 1 is used as a
boot area. After that, erase or write the original boot program area, boot cluster 0.
executed correctly because it is booted from boot cluster 1 to be swapped when the program is reset and started next.
information function of the firmware of the 78K0/Dx2.
830
If rewriting the boot area has failed during self-programming due to a power failure or some other cause, the data
The boot swap function is used to avoid this problem.
Before erasing boot cluster 0
As a result, even if a power failure occurs while the boot programming area is being rewritten, the program is
If the program has been correctly written to boot cluster 0, restore the original boot area by using the set
Note
Caution When executing boot swapping, do not use the E.P.V command with the dedicated flash memory
Remark Boot cluster 1 becomes 0000H to 0FFFH when a reset is generated after the boot flag has been set.
X X X X H
1 0 0 0 H
0 0 0 0 H
2 0 0 0 H
A boot cluster is a 4 KB area and boot clusters 0 and 1 are swapped by the boot swap function.
Boot cluster 0 (0000H to 0FFFH): Original boot program area
Boot cluster 1 (1000H to 1FFFH): Area subject to boot swap function
programmer.
(boot cluster 0)
User program
Boot program
User program
Boot
Note
Self programming
to boot cluster 1
Self programming
to boot cluster 0
, which is a boot program area, by self-programming, write a new boot program to
Figure 26-17. Boot Swap Function
Preliminary User’s Manual U19748EJ1V0UD
CHAPTER 26 FLASH MEMORY
X X X X H
1 0 0 0 H
0 0 0 0 H
2 0 0 0 H
New boot program
New boot program
New boot program
(boot cluster 1)
(boot cluster 0)
(boot cluster 1)
(boot cluster 0)
User program
User program
Boot program
Boot
Boot
Setting of boot flag
Setting of boot flag
New boot program
New boot program
New boot program
(boot cluster 1)
(boot cluster 0)
(boot cluster 1)
(boot cluster 0)
User program
Boot program
User program
Boot
Boot