Datasheet

V850ES/JG3 CHAPTER 27 FLASH MEMORY
R01UH0015EJ0300 Rev.3.00 Page 742 of 870
Sep 30, 2010
27.5.2 Features
(1) Secure self programming (boot swap function)
The V850ES/JG3 supports a boot swap function that can exchange the physical memory of blocks 0 to 15 with the
physical memory of blocks 16 to 31. By writing the start program to be rewritten to blocks 16 to 31 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 blocks 0 to 15.
Figure 27-16. Rewriting Entire Memory Area (Boot Swap)
Block 0
Block 1
:
Block 15
Block 16
Block 17
:
Block 31
Block 32
:
Last block
Block 0
Block 1
:
Block 15
Block 16
Block 17
:
Block 31
Block 32
:
Last block
Block 0
Block 1
:
Block 15
Block 16
Block 17
:
Block 31
Block 32
:
Last block
Boot swap
Rewriting blocks
16 to 31
(2) Interrupt support
Instructions cannot be fetched from the flash memory during self programming. Conventionally, a user handler
written to the flash memory could not be used even if an interrupt occurred.
Therefore, in the V850ES/JG3, to use an interrupt during self programming, processing transits to the specific
address
Note
in the internal RAM. Allocate the jump instruction that transits processing to the user interrupt servicing
at the specific address
Note
in the internal RAM.
Note NMI interrupt: Start address of internal RAM
Maskable interrupt: Start address of internal RAM + 4 addresses