Secure Self-Programming (Boot Cluster Swapping) - NEC V850ES/F 3-L Series User Manual

32-bit single-chip microcontroller

Table of Contents

Flash Memory

7.3.3 Secure self-programming (boot cluster swapping)

Boot swap cluster

Boot swap flag

The V850 flash microcontrollers support a mechanism to swap a cluster of

code flash memory blocks, starting from address 0000 0000

cluster of the same size, located immediately above the first one.

Boot cluster swapping is only supported, if the variable reset vector remains in

its default state 0000 0000

If the reset vector is changed to other values, boot cluster swapping is not

A group of boot blocks to be swapped. The cluster of blocks starting at address

is named active boot swap cluster, since it contains the entry point

of the user's program at the default reset vector 0000 0000

Which of the two clusters is the active boot block cluster is controlled by the

boot swap flag, that can be defined during flash programming via the self-

programming library.

The boot swap flag is stored in the flash memory extra area.

Figure 7-15 on page 279 shows an example of the boot block swapping

function with a cluster size of 4 flash memory blocks. After inverting the

boot_flag - it becomes not(boot_flag) - blocks 4 to 7 become the active boot

block cluster. Thus after next reset release the user's program starts from the

new boot swap cluster.

Boot swap cluster swapping function

User's Manual U18743EE1V2UM00

not(boot_flag)

, with another