Write Unprotect Command; Figure 18. Write Protect Command: Device Side - ST STM32F105 Series Application Note

AN2662

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.
(1)
Start WP
Received bytes =
0x63+0x9C?
Yes
ROP active
No
Send ACK byte
Receive the number of sectors
to be protected (1 byte)
Receive the sector codes
Receive the checksum
Checksum
OK?
Yes
Write-protect the requested sectors
Send ACK byte
Generate system reset
(1)
End of WP
Doc ID 14156 Rev 1
No
Yes
No
Send NACK byte
USART bootloader
ai14646b
33/83