AN3154 datasheet(26/34 Pages) STMICROELECTRONICS

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Bootloader command set

AN3154

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DocID017063 Rev 5

3.9

Write Protect command

The Write Protect command is used to enable the write protection for some or all Flash

memory sectors. When the bootloader receives the Write Protect command, it transmits the

ACK message to the host if ROP is disabled else it transmits NACK.

After the transmission of the ACK byte, the bootloader waits to receive the Flash memory

sector codes from the application.

At the end of the Write Protect command, the bootloader transmits the ACK message and

generates a system Reset to take into account the new configuration of the option byte.

Note:

Refer to Section 3.1: Get command for more details about the sector size for the device you

are using.

The total number of sectors and the sector number to be protected are not checked, this

means that no error is returned when a command is passed with a wrong number of sectors

to be protected or a wrong sector number.

If a second Write Protect command is executed, the Flash memory sectors that were

protected by the first command become unprotected and only the sectors passed within the

second Write Protect command become protected.

Figure 20. Write Protect command: host side

1. WP = Write Protect.

The host sends messages as follows:

Command message: Std ID = 0x63, DLC = 0x01, data[0] = N (where 0 < N

≤255).

Command message: Std ID = 0x63, DLC = 0x01..08, data[0] = N (where 0 < N

≤255).

After each message the host receives the ACK or NACK message from the device.

AN3154 Datasheet(PDF) 26 Page - STMicroelectronics