Generic universal serial bus device operable at low and full speed and adapted for use in a smart card device

• US 7,685,328 B2
• Filed: 09/09/2004
• Issued: 03/23/2010
• Est. Priority Date: 09/09/2004
• Status: Active Grant

• Current Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Incorporated (STMicroelectronics NV), Axalto SA (Thales SA)
• Inventors: Fruhauf, Serge, Leydier, Robert A.
• Primary Examiner(s): Chen; Alan
• Application Number:
  US10/937,752
• Publication Number:
  US 20060053244A1
• Time in Patent Office: 2,021 Days
• Field of Search: 710/11, 710/35, 710/58, 710/313
• US Class Current: 710/11
• CPC Class Codes: G06F 13/4068 Electrical coupling

Abstract

A USB device, integrated circuit, smart card and method are disclosed. A USB transceiver is connected to a data interface and operable at a respective low speed and full speed configuration. A processor as a USB device controller is operatively connected to the low speed USB transceiver and full speed USB transceiver and operable for transmitting a different device descriptor to a USB host for performing an enumeration depending on whether a low speed or high speed operation is chosen.

Claims

1. A method of operating a smart card device, comprising;

connecting a USB host device as a master to a USB smart card device via a smart card reader that is coupled to the host device for reading the smart card device and including a USB bus, wherein the smart card device comprises an integrated circuit comprising D+ and D−

ports forming an interface circuit, a single serial interface engine that translates USB data into parallel data, a low speed USB transceiver and separate full speed USB transceiver connected in parallel between the serial interface engine and the interface circuit, a processor, a data memory storing programmable USB configurations and connected to the processor, a USB device controller coupled to the serial interface engine and processor and a buffer connected between the processor, USB device controller and serial interface engine through which programmable configurations are loaded to the USB device controller and serial interface engine, and a clock source coupled to the processor, serial interface engine and USB device controller for switching clock speed operation for a low speed clock speed or a full speed clock speed;

attaching to the USB host device and USB bus and powering-on the USB smart card device, low speed in a default configuration by powering the low speed transceiver only and the clock source in a low speed configuration;

enumerating to the USB host device as a low speed USB smart card device and operating as a low speed device;

detecting an event indicative that the USB smart card device should switch to a full speed mode;

detaching from the USB host device and USB bus;

disabling the USB smart card device by switching off power to the USB device controller;

switching the clock source to a full speed clock speed and switching out from the low speed transceiver operation and enabling full speed transceiver operation; and

attaching to the USB bus and enumerating to the USB host as a full speed USB smart card device while the USB host device sends a new set of descriptors to operate in full speed.

2. method according to claim 1, and further comprising detecting subsequent events and switching between full and low speed operation as necessary by disabling the USB smart card device and switching the clock circuit and transceiver operation as necessary for low or full speed operation and reattaching.

3. method according to claim 1, and further comprising operating the USB smart card either a USB or ISO mode.

4. method according to claim 1, and further comprising reading the smart card through a pass through connector that is incorporated within the smart card device.

5. method according to claim 1, and further comprising enumerating as a low speed USB device to the USB host by connecting at least one pull-up resistor to the D−

port of the interface circuit.

6. method according to claim 1, and further comprising detaching from the USB host by disconnecting at least one pull-up resistor to the D−

port and detaching from the USB bus.

7. method according to claim 1, and further comprising transmitting a GetDescriptor request for uploading a different response depending on the speed of the device.

8. method according to claim 1, and further comprising configuring an endpoint0 and control transfer when the low speed USB transceiver is enabled.

9. method according to claim 1, and further comprising configuring an endpoint0 and control transfer for sending a configuration to a USB host during high speed operation.

10. method according to claim 1, and further comprising configuring two endpoints In and Out for Bulk transfer of data at irregular intervals.

11. method according to claim 1, and further comprising updating a device descriptor using an application bus.