
AN2662
USART bootloader
Doc ID 14156 Rev 1
Figure 18.
Write Protect command: device side
1.
WP = Write Protect.
2.14
Write Unprotect command
The Write Unprotect command is used to disable the write protection of all the Flash
memory sectors. When the bootloader receives the Write Unprotect command, it transmits
the ACK byte to the host. After the transmission of the ACK byte, the bootloader disables the
write protection of all the Flash memory sectors. After the unprotection operation the
bootloader transmits the ACK byte.
At the end of the Write Unprotect command, the bootloader transmits the ACK byte and
generates a system Reset to take into account the new configuration of the option byte.
ROP active
Receive the number of sectors
to be protected (1 byte)
No
Yes
ai14646b
Start WP
(1)
No
Received bytes =
0x63+0x9C?
Send ACK byte
Receive the sector codes
Checksum
OK?
Send NACK byte
End of WP
(1)
Yes
No
Yes
Receive the checksum
Write-protect the requested sectors
Send ACK byte
Generate system reset