13

4256B–USB–03/06

AT89C5132

Table 10. DFU Mode Device Descriptor

DFU Configuration

Descriptor

This descriptor is identical to the standard configuration descriptor described in the USB DFU

specification version 1.0, with the exception that the bNumInterfaces field must contain the value

01h.

DFU Interface

Descriptor

This is the descriptor for the only interface available when operating in DFU mode. Therefore,

the value of the bInterfaceNumber field is always zero.

Table 11. DFU mode Interface Descriptor

Note:

1. Alternate settings can be used by an application to access additional memory segments. In

this case, it is suggested that each alternate setting employs a string descriptor to indicate the

target memory segment; e.g., “EEPROM”. Details concerning other possible uses of alternate

settings are beyond the scope of this document. However, their use is intentionally not

Offset

Field

Size

Value

Description

0

bLength

1

12h

Size of this descriptor, in bytes

1

bDescriptorType

1

01h

DFU FUNCTIONAL descriptor type

2

bcdUSB

2

0100h

USB specification release number in binary coded decimal

4

bDeviceClass

1

FEh

Application Specific Class Code

5

bDeviceSubClass

1

01h

Device Firmware Upgrade Code

6

bDeviceProtocol

1

00h

The device does not use a class specific protocol on this

interface

7

bMaxPacketSize0

1

32

Maximum packet size for endpoint zero

8

idVendor

2

03EBh

Vendor ID

10

idProduct

2

2FFFh

Product ID

12

bcdDevice

2

0x0000

Device release number in binary coded decimal

14

iManufacturer

1

0

Index of string descriptor

15

iProduct

1

0

Index of string descriptor

16

iSerialNumber

1

0

Index of string descriptor

17

bNumConfigurations

1

01h

One configuration only for DFU

Offset

Field

Size

Value

Description

0

bLength

1

09h

Size of this descriptor, in bytes

1

bDescriptorType

1

04h

INTERFACE descriptor type

2

bInterfaceNumber

1

00h

Number of this interface

3

bAlternateSetting

1

00h

4

bNumEndpoints

1

00h

Only the control pipe is used

5

bInterfaceClass

1

FEh

Application Specific Class Code

6

bInterfaceSubClass

1

01h

Device Firmware Upgrade Code

7

bInterfaceProtocol

1

00h

The device doesn’t use a class specific protocol on

this interface

8

iInterface

1

00h

Index of the String descriptor for this interface