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DEVICE FIRMWARE UPGRADE (DFU) IMPLEMENTATION IN ST7 USB DEVICES

2.3 REQUESTS

A number of DFU class-specific requests are needed to accomplish the upgrade operations.

The following table summarizes the DFU class-specific requests.

For additional information about these requests, please refer to the DFU Class specification.

2.4 ENUMERATION PHASE

A device with DFU capability must be able to be enumerated in two ways by the host:

- As a single device with only DFU capability.

- As a composite device: HID, Mass storage, or any functional class, and with DFU capability.

During the enumeration phase, the device exposes two distinct and independent descriptor

sets, one each at the appropriate time:

- Run-time descriptor set: shown when the device performs normal operations.

- DFU mode descriptor set: shown when host and device agree to perform DFU operations.

Table 1. Summary of DFU Class-Specific Requests

bmRequestType

bRequest

wValue

wIndex

wLength

Data

00100001b

DFU_DETACH

(0)

wTimeout

Interface

Zero

None

00100001b

DFU_DNLOAD

(1)

wBlockum

Interface

Length

Firmware

10100001b

DFU_UPLOAD

(2)

Zero

Interface

Length

Firmware

10100001b

DFU_GETSTATUS

(3)

Zero

Interface

6

Status

00100001b

DFU_CLRSTATUS

(4)

Zero

Interface

Zero

None

10100001b

DFU_GETSTATE

(5)

Zero

Interface

1

State

00100001b

DFU_ABORT

(6)

Zero

Interface

Zero

None