USB Interface

AN2271

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USB Interface

This solution uses a USB Composite Device to combine the Ekey and Udisk functions into

one USB device.

The Ekey function uses an HID protocol, and the Udisk function uses a Mass Storage

protocol. Both of these two functions use a Microsoft driver, so when an Ekey-Udisk device

plugs in, Windows2000/XP recognizes one USB composite device comprised of one HID

device and one Mass Storage device. No extra driver is needed.

The USB interface for Udisk is traditional.

The USB interface for Ekey is shown below, and the PC Application Software can use this

data structure to communicate with Ekey through the HID driver.

Enumerating a USB composite device with HID and a Mass Storage device is listed in the

file descript.c

According to the HID protocol, PC communication is configured in USER_USB_Setup() in

User_lib.c

Note:

According to the limitation of the HID driver, in order to save time to send data to the device,

PC Application Software should select the correct Report ID based on the Message Length.

9 report types are provided for use with supporting lengths from 0x0f to 0x8f. If necessary,

additional descriptors can be created by modifying these to provide other report types.

Table 1.

Report ID based on message length

Report ID (1 Byte)

Message Length (1 Byte)

Data (1-128 Bytes)

ID

Length

Data Length

1

0x01~0x0f

Data(0x01~0x0f bytes)

2

0x01~0x1f

Data(0x01~0x1f bytes)

3

0x01~0x2f

Data(0x01~0x2f bytes)

4

0x01~0x3f

Data(0x01~0x3f bytes)

5

0x01~0x4f

Data(0x01~0x4f bytes)

6

0x01~0x5f

Data(0x01~0x5f bytes)

7

0x01~0x6f

Data(0x01~0x6f bytes)

8

0x01~0x7f

Data(0x01~0x7f bytes)

9

0x01~0x8f

Data(0x01~0x8f bytes)