DocID017068 Rev 4

11/26

AN3156

DFU bootloader commands

25

If you perform a Read Unprotect operation while the memory is not protected, the entire

RAM memory is cleared by the bootloader firmware and the Flash memory is not erased

(since it was not previously read-protected).

There are no commands for the Write Protect, Write Unprotect and Read Protect

operations. These operations should be performed through the Write Memory and Read

Memory commands used for the option byte area.

Table 4. DFU bootloader commands

DFU request

Bootloader

command

Write protection

disabled

Read protection

disabled

Write protection

enabled

Read protection

disabled

Read protection

enabled

DFU_UPLOAD

Read Memory

Allowed

Allowed

Not allowed

Get

Allowed

Allowed

Allowed

DFU_DNLOAD

Write Memory

Allowed

1. This operation is allowed but not effective: the bootloader does not return an error but the operation is not

executed since the sectors are write-protected. This applies only to the Flash memory. It does not apply to

the RAM memory or the option byte area.

Not allowed

Erase

Allowed

Allowed(1)

Not allowed

Read Unprotect

2. This operation is allowed but has no meaning since the memory is not protected.

NA(2)

3. In this case, both the Flash memory (from 0x0800 0000) and the RAM are erased. The option byte area is

reset to default values.

Set Address Pointer

Allowed

Allowed

Allowed

Leave DFU mode

Allowed

Allowed

Allowed