USART bootloader AN2662
36/83 Doc ID 14156 Rev 1
Figure 22. Readout Protect command: device side
1. RDP_PRM = Readout Protect.
2.16 Readout Unprotect command
The Readout Unprotect command is used to disable the Flash memory read protection.
When the bootloader receives the Readout Unprotect command, it transmits the ACK byte
to the host. After the transmission of the ACK byte, the bootloader erases all the Flash
memory sectors and it disables the read protection for the entire Flash memory. If the erase
operation is successful, the bootloader deactivates the RDP.
If the erase operation is unsuccessful, the bootloader transmits a NACK and the read
protection remains active.
At the end of the Readout Unprotect command, the bootloader transmits an ACK and
generates a system Reset to take into account the new configuration of the option byte.
ROP active
Activate Read protection for Flash
memory
No
Ye s
ai14650b
Start RDP_PRM
(1)
Received bytes =
0x82+0x7D?
Send ACK byte
Send NACK byte
End of RDP_PRM
(1)
No
Ye s
Send ACK byte
Generate system reset
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