MULTIPLE COMMUNICATION CHANNELS ON MMC OR SD CMD LINE

• US 20080059668A1
• Filed: 09/01/2006
• Published: 03/06/2008
• Est. Priority Date: 09/01/2006
• Status: Active Grant

• Current Assignee: Spansion LLC (Infineon Technologies AG)
• Original Assignee: Spansion LLC (Infineon Technologies AG)
• Inventors: Charrat, Bruno, Prawitz, Nicolas, Kornitz, Roni, Grall, Jean-Yves
• Granted Patent: US 8,156,272 B2
• Time in Patent Office: Days
• US Class Current: 710/110
• CPC Class Codes: G06F 13/4243 with synchronous protocol

Abstract

The claimed subject matter can provide an architecture that interfaces a single slave device such as a UICC smartcard with multiple host controllers. For example, a secondary host can be interfaced between a primary host (e.g. a controller in a cellular phone, a PDA, an MP3 player . . . ) to manage all transactions with the slave device. The secondary host can operate transparently to the primary host and thus does not require any modifications to the primary host. This can be accomplished, e.g. by employing the CMD channel (which is relatively sparsely used by the primary host) to communicate both commands and data with the slave. Moreover, the transactions initiated by the secondary host can be segmented into many smaller fragments and interleaved between transactions initiated by the primary host. In addition, the secondary host can temporarily take on the role of the slave device and affect direct communication with the primary host.

Claims

1. A system that facilitates multiple hosts for a slave device, comprising:

an interface that facilitates transmission of a transaction between a primary host and a slave device, the interface includes a clock channel, a command channel and at least one data channel; and

a secondary host operatively coupled to the interface, the secondary host manages the clock channel and the command channel for all transactions.

2. The system of claim 1, the interface conforms to at least one of the following standards:

MMC and SD.

3. The system of claim 1, the secondary host mirrors signals on at least one of the clock channel and the command channel to facilitate the transaction between the primary host and the slave device.

4. The system of claim 1, the secondary host operates transparently to the primary host.

5. The system of claim 1, the interface facilitates transmission of a second transaction between the secondary host and the slave device.

6. The system of claim 5, the second transaction includes information from a contactless device.

7. The system of claim 5, the command channel is utilized to transfer both commands and data for the second transaction.

8. The system of claim 5, the secondary host divides the second transaction into a plurality of fragments.

9. The system of claim 8, the secondary host interleaves the plurality of fragments between at least one transaction initiated by the primary host.

10. The system of claim 8, each of the plurality of fragments is about 4 bytes in size.

11. The system of claim 1, the secondary host intercepts and drops signals on at least one of the clock channel and the command channel when the primary host attempts the transaction with the slave device.

12. The system of claim 11, the primary host retries the attempted transaction and the secondary host mirrors the corresponding signals to the slave device.

13. The system of claim 1, the secondary host asserts a busy signal on the at least one data channels when the primary host attempts a transaction with the slave device.

14. The system of claim 1, the primary host is at least one of a cellular phone, a digital camera, an organizer, a Personal Digital Assistants (PDA), a digital recorder, an MP3 player, a pager, an electronic toy, an electronic game, a scanner/reader, a computer, a computerized device, and a contactless device.

15. The system of claim 1, the slave device is at least one of a smartcard, a Subscriber Identity Module (SIM) card, a Universal Subscriber Identity Module (USIM), a Universal Integrated Circuit Card (UICC), a MultiMediaCard (MMC) card, a computer, a computerized device, a contacless device, and a Secure Digital (SD) card.

16. The system of claim 1, the secondary host is a contactless integrated circuit.

17. The system of claim 1, the secondary host simulates operation of the slave device to effectuate transactions between the primary host and the secondary host.

18. A computer-implemented method for facilitating multiple communication channels on an MMC or SD CMD channel, comprising:

segmenting a transaction between a secondary host and a slave into a plurality of fragments;

determining whether it is necessary to assert a clock channel for directing bit transfers between the secondary host and the slave;

asserting the clock channel when the secondary host determines it is necessary; and

employing a command channel of an interface conforming to an MMC or SD standard to transmit the plurality of fragments.

19. The method of claim 18, further comprising interleaving the fragments between transactions occurring on the command channel between the primary host and the slave.

20. A system for sharing an MMC or SD interface to a slave between a primary host and a secondary host with no modifications to the primary host, comprising:

means for dividing data comprising a transaction between a secondary host and a slave into a plurality of sections;

means for sensing whether the command channel is free for use;

means for ascertaining whether it is required to activate a clock channel for controlling bit transfers between the secondary host and the slave;

means for activating the clock channel when the secondary host ascertains it is required; and

means for employing a command channel of an interface to convey the plurality of sections according to an interleaved approach.