DEVICE-DEPENDENT SELECTION BETWEEN MODES FOR ASYMMETRIC SERIAL PROTOCOLS

• US 20110055407A1
• Filed: 09/01/2009
• Published: 03/03/2011
• Est. Priority Date: 09/01/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Lydon, Gregory T., Bolton, Lawrence G.
• Granted Patent: US 8,626,932 B2
• Time in Patent Office: Days
• US Class Current: 709/228
• CPC Class Codes: G06F 13/385 for adaptation of a particular data processing system to different peripheral devices
• CPC Class Codes: G06F 13/387 for adaptation of different data processing systems to different peripheral devices, e.g. protocol converters for incompatible systems, open system
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A portable communication device (PCD) can automatically switch into different operating modes of an asymmetric communication protocol (such as USB) depending on the type of accessory connected. For example, the accessory can signal whether the PCD should operate in a first mode or a second mode using a hardware indicator such as identification resistor across two pins of a multi-pin connector and/or a software indicator such as a command protocol. The PCD can detect the accessory'"'"'s signal and switch to the operating mode requested by the accessory.

Claims

1. A method for use in a portable communication device, the method comprising:

establishing a connection to an accessory;

determining whether a mode-selecting signal is received from the accessory, the mode-selecting signal indicating whether the portable communication device is to operate in a first mode or a second mode of an asymmetric communication protocol;

in the event that the mode-selecting signal is received from the accessory, operating the portable communication device in the mode indicated by the mode-selecting signal; and

in the event that the mode-selecting signal is not received from the accessory, operating the portable communication device in the first mode of the asymmetric communication protocol.

2. The method of claim 1 wherein the connection to the accessory is established using a connector having a plurality of pins and wherein determining whether the mode-selecting signal is received from the accessory includes:

sensing a resistance across two pins of the plurality of pins; and

determining whether the sensed resistance satisfies a first criterion,

wherein the second mode is indicated in the event that the sensed resistance satisfies the first criterion.

3. The method of claim 2 wherein the two pins that are used for sensing the resistance are used exclusively for sensing the resistance.

4. The method of claim 2 wherein the asymmetric communication protocol is a Universal Serial Bus (USB) protocol, the first mode corresponds to a device mode of the USB protocol, and the second mode corresponds to a host mode of the USB protocol.

5. The method of claim 4 further comprising:

determining whether the sensed resistance satisfies a second criterion,

wherein operating the portable communication device in a first mode of the asymmetric communication protocol includes;

operating the portable communication device in a Human Interface Device configuration of a device mode of the USB protocol in the event that the sensed resistance satisfies the second criterion; and

operating the portable communication device in a mass storage configuration of the device mode of the USB protocol in the event that the sensed resistance does not satisfy the second criterion.

6. The method of claim 1 wherein the portable communication device further supports a device-specific protocol, the method further comprising:

initiating an authentication operation with the accessory according to the device-specific protocol;

determining whether the authentication operation is successful; and

in the event that the authentication operation is not successful, blocking the accessory from using at least one function associated with the asymmetric communication protocol.

7. The method of claim 1 wherein the connection to the accessory is established using a connector having a plurality of pins and wherein:

operating the portable communication device in the first mode includes receiving a first voltage level on a first power pin of the plurality of pins, and

operating the portable communication device in the second mode includes providing a second voltage level on a second power pin of the plurality of pins, wherein the first voltage level is greater than the second voltage level.

8. The method of claim 1 wherein determining whether a mode-selecting signal is received from the accessory includes determining whether a mode-selecting command has been received from the accessory.

9. A portable communication device comprising:

a processor;

a power control module coupled to the processor; and

an accessory interface coupled to the processor and the power control module, the accessory interface including;

a connector having a plurality of pins, the plurality of pins including a data pin associated with an asymmetric communication protocol, a power input pin coupled to the power control module, a power output pin coupled to the power control module, and a pair of accessory identification pins; and

a sensor connected to detect a resistance applied across the pair of accessory identification pins and configured to generate an identification signal indicative of the detected resistance,

wherein the power control module is configured to determine, based on the identification signal, whether to provide a first power to the power output pin or to receive a second power from the power input pin; and

wherein the accessory interface is configured to determine, based at least in part on the identification signal, whether to operate in a first mode or a second mode of the asymmetric communication protocol.

10. The portable communication device of claim 9 wherein the asymmetric communication protocol is a USB protocol.

11. The portable communication device of claim 9 wherein the power control module is further configured such that the first power and the second power are at different voltage levels.

12. The portable communication device of claim 9 wherein the accessory interface is further configured to receive a mode-selection command from the accessory and to determine whether to operate in the first mode or the second mode of the asymmetric communication protocol based in part on the identification signal and in part on the received mode-selection command.

13. A portable communication device comprising:

a processor; and

an accessory interface coupled to the processor, the accessory interface being configured to selectively operate in a first mode or a second mode of an asymmetric communication protocol,

the accessory interface being further configured to receive a mode-selection command from the accessory and to determine, based at least in part on the mode-selection command, whether to operate in the first mode or the second mode of the asymmetric communication protocol.

14. The portable communication device of claim 13 wherein the asymmetric communication protocol is a USB protocol.

15. The portable communication device of claim 13 wherein the accessory interface includes a connector having a plurality of pins, the plurality of pins including a power input pin and a power output pin, the portable communication device further comprising:

a power control module coupled to the power input pin and the power output pin,

the power control module being configured to receive power from the power input pin when the accessory interface is operating in the first mode of the asymmetric communication protocol and to provide power to the power output pin when the accessory interface is operating in the second mode of the asymmetric communication protocol.

16. An accessory for use with a portable communication device, the accessory comprising:

a controller operable in a device mode of a Universal Serial Bus (USB) protocol;

a connector coupled to the controller and adapted to connect to a portable communication device, the connector having a plurality of pins, the plurality of pins including a USB power pin, a USB ground pin, two USB data pins, and a pair of accessory identification pins; and

a resistor connected between the accessory identification pins, wherein the resistor has a resistance value indicating to the portable communication device that the portable communication device should operate in a host mode of the USB protocol.

17. The accessory of claim 16 wherein the plurality of pins further includes a power input pin to receive power from the portable communication device.

18. The accessory of claim 17 wherein the power received from the portable communication device is at a lower voltage level than a standard USB voltage level.

19. The accessory of claim 18 wherein the power received from the portable communication device is at a voltage level of approximately 3.3 volts.

20. A method for use in an accessory, the method comprising:

establishing a connection to a portable communication device, wherein the portable communication device is switchable between a first mode and a second mode of an asymmetric communication protocol;

sending a first command to the portable communication device, the first command specifying a first requested mode of operation to be used by the portable media device, the first requested mode being one of the first mode or the second mode,

wherein in the event that the accessory operates in the first mode of the asymmetric communication protocol, the requested mode is the second mode, and wherein in the event that the accessory operates in the second mode of the asymmetric communication protocol, the requested mode is the first mode; and

communicating with the portable media device using the asymmetric communication protocol.

21. The method of claim 20 further comprising:

prior to sending the first command, selecting the requested mode based at least in part on a current configuration of the accessory.

22. The method of claim 20 wherein the first command is sent using a transport that is independent of the asymmetric communication protocol.

23. The method of claim 20 further comprising:

sending a second command to the portable communication device, the second command specifying a second requested mode of operation to be used by the portable media device, the second requested mode being different from the first requested mode.

24. A method for use in an accessory, the method comprising:

establishing a connection to a portable communication device using a connector having a plurality of pins, wherein the portable communication device is switchable between a first mode and a second mode of an asymmetric communication protocol;

applying a resistance across a first pin and a second pin of the plurality of pins, wherein the resistance has a value indicating to the portable communication device that the accessory operates in the first mode of the asymmetric communication protocol;

receiving power from the portable communication device via a third pin of the plurality of pins; and

communicating with the portable communication device using the first mode of the asymmetric communication protocol.

25. The method of claim 24 wherein the asymmetric communication protocol is a Universal Serial Bus (USB) protocol and the first mode is a device mode of the USB protocol.

26. The method of claim 25 wherein receiving the power from the portable communication device includes receiving the power at a voltage level lower than a standard voltage level of the USB protocol.

27. The method of claim 25 wherein communicating with the portable communication device using the first mode of the asymmetric communication protocol includes sending USB-compliant enumeration data to the portable communication device.

28. The method of claim 27 further comprising, after sending the USB-compliant enumeration data:

sending a command to the portable communication device, wherein the command is one of a plurality of commands of a device-specific protocol supported by the portable communication device,

wherein sending the command includes using the asymmetric communication protocol as a transport.