UPD78F0890GK(A)-GAJ-AX NEC, UPD78F0890GK(A)-GAJ-AX Datasheet - Page 628

• Manufacturer Part Number: UPD78F0890GK(A)-GAJ-AX
• Description: 8BIT MCU, 128K FLASH, 7K RAM, LQFP
• Manufacturer: NEC

Specifications of UPD78F0890GK(A)-GAJ-AX

• Controller Family/series: UPD78F
• No. Of I/o's: 55
• Ram Memory Size: 7KB
• Cpu Speed: 20MHz
• No. Of Timers: 10
• No. Of Pwm: RoHS Compliant
• Core Size: 8bit
• Program Memory Size: 128KB
• Oscillator Type: External, Internal

24.11 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/FE2, 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/FE2.
628
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
Boot cluster 0 (0000H to 0FFFH): Original boot program area
Boot cluster 1 (1000H to 1FFFH): Area subject to boot swap function
Note A boot cluster is a 4 KB area and boot clusters 0 and 1 are swapped by the boot swap function.
X X X X H
1 0 0 0 H
0 0 0 0 H
2 0 0 0 H
(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 24-20. Boot Swap Function
CHAPTER 24 FLASH MEMORY
X X X X H
1 0 0 0 H
0 0 0 0 H
2 0 0 0 H
User’s Manual U17554EJ4V0UD
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
Execution of boot
swap by firmware
Execution of boot
swap by firmware
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