Features - NEC V850ES/KE1+ User Manual

26.5.2 Features

(1) Secure self programming (boot swap function)
The V850ES/KE1+ supports a boot swap function that can exchange the physical memory (blocks 0 to 3) of
boot area 0 with the physical memory (blocks 4 to 7) of boot area 1. By writing the start program to be
rewritten to boot area 1 in advance and then swapping the physical memory, the entire area can be safely
rewritten even if a power failure occurs during rewriting because the correct user program always exists in boot
area 0.
(2) Interrupt support
<R>
Instructions cannot be fetched from the flash memory during self programming. Conventionally, therefore, a
user handler written to the flash memory could not be used even if an interrupt occurred.
Therefore, in the V850ES/KE1+, to use an interrupt during self programming, processing transits to the specific
address
servicing at the specific address
Note NMI interrupt:
Maskable interrupt: Start address of internal RAM + 4 addresses
Figure 26-16. Rewriting Entire Memory Area (Boot Swap)
Block 63
Block 8
Block 7
Block 6
Block 5
Rewriting boot
Block 4
areas 0 and 1
Block 3
Block 2
Block 1
Block 0
Note
in the internal RAM. Allocate the jump instruction that transits processing to the user interrupt
Note
in the internal RAM.
Start address of internal RAM
CHAPTER 26 FLASH MEMORY
Block 63
Boot swap
Block 8
Block 7
Block 6
Block 5
Block 4
Block 3
Block 2
Block 1
Block 0
User's Manual U16896EJ2V0UD
Block 63
Block 8
Block 7
Block 6
Block 5
Block 4
Block 3
Block 2
Block 1
Block 0
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