Multiple communication channels on MMC or SD CMD line
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.
1. A system, comprising:
an interface that facilitates transactions between a primary host and a slave device, the interface includes a clock channel, a command channel and at least one data channel, wherein the interface interleaves fragments of transactions between a secondary host and the slave device between transactions occurring on the command channel between the primary host and the slave device; and
wherein the secondary host is operatively coupled to the interface, wherein the secondary host manages the clock channel and the command channel for the transactions.
2. The system of claim 1 , the interface conforms to at least one of the MMC and SD standards.
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 , wherein the secondary host does not interfere with normal interactions between the primary host and the slave device.
5. The system of claim 1 , wherein the interface facilitates transmission of a second transaction between the secondary host and the slave device.
6. The system of claim 5 , wherein the second transaction includes information transmitted from a contactless device.
7. The system of claim 5 , wherein the command channel is utilized to transfer both commands and data for the second transaction.
8. The system of claim 1 , wherein each of the fragments is 4 bytes in size.
9. The system of claim 1 , wherein the secondary host intercepts and drops signals on the clock channel and the command channel in response to the the primary host attempting the transaction with the slave device.
10. The system of claim 9 , wherein the primary host retries the attempted transaction and the secondary host mirrors the corresponding signals to the slave device.
11. The system of claim 1 , wherein the secondary host asserts a busy signal on the at least one data channels in response to the the primary host attempting a transaction with the slave device.
12. The system of claim 1 , wherein the primary host is an electronic device.
13. The system of claim 1 , wherein the slave device is a memory card.
14. The system of claim 1 , wherein the secondary host is a contactless integrated circuit.
15. The system of claim 1 , wherein the secondary host simulates operation of the slave device to effectuate transactions between the primary host and the secondary host.
16. A method, comprising:
segmenting, by a system including at least one processor, a transaction between a secondary host and a slave into a plurality of fragments;
determining, by the system, whether it is necessary to assert a clock channel for directing bit transfers between the secondary host and the slave;
asserting, by the system, the clock channel when the secondary host determines it is necessary;
employing, by the system, a command channel of an interface conforming to an MMC or SD standard to transmit the plurality of fragments; and
interleaving, by the system, the fragments between transactions occurring on the command channel between the primary host and the slave.
17. A system, comprising:
means for dividing data comprising a transaction between a secondary host and a slave into a plurality of sections;
means for interleaving the plurality of sections between a primary host transactions occurring on a command channel between a primary host and the slave;
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.
18. The system of claim 1 , wherein the secondary host verifies that the command channel is free for use to prevent contention and waits until the command channel is free if the command channel is in use by the primary host.
19. The system of claim 1 , wherein the primary host terminates activity on the clock channel in response to transactions between the primary host and the slave being completed.
20. The system of claim 1 , wherein if the fragments are larger than 4 bytes, the primary host utilizes an SD command format.