DFU_UPLOAD request commands

AN3156

12/26

DocID017068 Rev 4

4

DFU_UPLOAD request commands

The upload request allows different commands to be performed. The command selection is

done through the value of parameter wValue in the USB request structure. The operations

described in Section 4.1 to Section 5.5 are supported.

4.1

Read memory

The Read memory operation is selected when wValue > 1.

memory address (see note) of the internal Flash memory, embedded RAM, system memory

or from the option bytes.

Note:

Refer to Section 4: DFU_UPLOAD request commands for more details about the valid

memory addresses for the device you are using.

The allowed number of bytes to be read depends on the memory target:

•

For the internal Flash memory, embedded RAM and system memory: read size can be

from 2 to 2048 bytes

•

For the option bytes: read size should be equal to the option byte block size

•

For other memory locations, refer to the section "Important considerations” depending

on the product in AN2606.

The address, from which the host requests to read data, is computed using the value of

wBlockNumber (wValue) and the address pointer according to the following formula:

Address = ((wBlockNum – 2) × wTransferSize) + Address_Pointer, where:

–

wTransferSize is the length of the requested data buffer.

The address pointer should be previously specified through a Set Address Pointer

command (using a DFU_DNLOAD request). Otherwise (if no address was previously

specified) the device assumes that it is the internal Flash start address (0x08000000).

If the Flash Read Protection is enabled, the Read operation is not performed and the

returned device status is (Status = dfuERROR, State = errVENDOR) whatever the target

(internal Flash memory, embedded RAM, system memory or option bytes).

4.2

Get command

This command is selected when wValue = 0.

The host requests to read the commands supported by the bootloader. After receiving this

command, the device returns N bytes representing the command codes.

The STM32 sends bytes as follows (N = 4):

Byte 1:

0x00

- Get command

Byte 2:

0x21

- Set Address Pointer

Byte 3:

0x41

- Erase

Byte 4:

0x92

- Read Unprotect