Gated power management over a system bus

• US 20080162967A1
• Filed: 01/03/2007
• Published: 07/03/2008
• Est. Priority Date: 01/03/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Wilson, Thomas James, Reeve, Richard James
• Granted Patent: US 8,405,617 B2
• Time in Patent Office: Days
• US Class Current: 713/322
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/324 by lowering clock frequency
• CPC Class Codes: G06F 1/3253 Power saving in bus
• CPC Class Codes: G06F 1/3262 Power saving in digitizer or tablet
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A method and system for managing power in a computer system is disclosed. In one embodiment the method includes providing output signals from a sensor panel to a controller, wherein the controller includes a data bus and a plurality of devices communicatively coupled to the data bus; monitoring an activity level on the data bus by monitoring bus access requests by one or more of the plurality of devices; and reducing or shutting off a bus clock frequency if there is reduced or no activity on the bus for a predetermined period of time.

Claims

1. A method of managing power in a computer system utilizing a touch surface device, the method comprising:

providing output signals from a sensor panel to a controller, wherein the controller includes a data bus and a plurality of devices communicatively coupled to the data bus;

monitoring an activity level on the data bus by monitoring bus access requests by one or more of the plurality of devices; and

reducing a bus clock frequency if there is reduced or no activity on the bus for a first predetermined period of time.

2. The method of claim 1 further comprising disabling one or more clocks corresponding to one or more devices until the one or more devices require access to the bus.

3. The method of claim 1 wherein the plurality of devices comprises at least one primary device and at least one secondary device, wherein a clock frequency applied to the data bus is slowed when the at least one primary device has not requested access to the bus for the first predetermined length of time.

4. The method of claim 3 further comprising disabling a clock provided to the at least one secondary device when the at least one secondary device is not being accessed by the at least one primary device over the bus.

5. The method of claim 3 further comprising:

detecting a request to access the bus;

returning the bus clock frequency to a predetermined active frequency; and

maintaining the bus clock frequency at the active frequency until there has been no activity on the bus for the first predetermined length of time.

6. The method of claim 1 further comprising further reducing the bus clock frequency if there has been no activity on the bus for a second predetermined period of time, which is longer than the first predetermined period of time.

7. The method of claim 1 further comprising providing a separate clock signal to each of the plurality of devices.

8. A method of managing power in a computer system utilizing a touch surface device, the method comprising:

providing output signals from a sensor panel to a controller, wherein the controller includes a data bus and a plurality of devices communicatively coupled to the data bus;

providing a separate clock signal to each of the plurality of devices;

monitoring bus access requests made by one or more of the plurality of devices; and

disabling a clock signal provided to a first device among the plurality of devices until the at least one device requires access to the bus.

9. The method of claim 8 further comprising reducing a bus clock frequency if there are no bus access requests made by the plurality of devices for a first predetermined period of time.

10. The method of claim 8 wherein the plurality of devices comprises at least one primary device and at least one secondary device, wherein a clock frequency applied to the data bus is slowed when the at least one primary device has not requested access to the bus for a first predetermined length of time.

11. The method of claim 10 further comprising disabling a clock provided to the at least one secondary device when the at least one secondary device is not being accessed by the at least one primary device over the bus.

12. The method of claim 10 further comprising further reducing the bus clock frequency if there has been no activity on the bus for a second predetermined period of time, which is longer than the first predetermined period of time.

13. A method of managing power in an integrated circuit having a data bus and a plurality of devices communicating over the data bus, the method comprising:

monitoring an activity level on the data bus by monitoring bus access requests by one or more of the plurality of devices; and

reducing a bus clock frequency if there is reduced or no activity on the bus for a first predetermined period of time.

14. A method of managing power in an integrated circuit having a data bus and a plurality of devices communicating over the data bus, the method comprising:

providing a separate clock signal to each of the plurality of devices;

monitoring bus access requests made by one or more of the plurality of devices; and

disabling a clock signal provided to a first device among the plurality of devices until the at least one device requires access to the bus.

15. A computer system, comprising:

a sensor panel configured to generate an output signal indicative of a touch or no-touch condition on the panel;

a controller coupled to the sensor panel and configured to receive the output signal, the controller comprising a data bus and a plurality of devices communicatively coupled to the data bus;

an arbiter coupled to the data bus and configured to monitor bus access requests made by the plurality of devices; and

a clock module, coupled to the arbiter, and configured to provide a separate clock signal to each of the plurality of devices, wherein the clock module reduces a clock frequency applied to the data bus if there are no bus access requests made by the plurality of devices for a first predetermined period of time.

16. The system of claim 15 wherein the clock module further disables a clock signal applied to at least one device among the plurality of devices until the at least one device requires access to the bus.

17. The system of claim 15 wherein the plurality of devices comprises at least one primary device and at least one secondary device, wherein a clock frequency applied to the data bus is slowed when the at least one primary device has not requested access to the bus for the first predetermined length of time.

18. The system of claim 17 wherein the at least one primary device comprises a microcontroller.

19. The system of claim 17 wherein the at least one primary device comprises a channel scan logic module.

20. The system of claim 17 wherein the at least one primary device comprises a direct memory access controller.

21. The system of claim 17 wherein the clock module further disables a clock provided to the at least one secondary device when the at least one secondary device is not being accessed by the at least one primary device over the bus.

22. The system of claim 21 wherein the at least one secondary device comprises a boot ROM.

23. The system of claim 21 wherein the at least one secondary device comprises a serial peripheral interface.

24. A computer system, comprising:

a sensor panel configured to generate an output signal indicative of a touch or no-touch condition on the panel;

a controller coupled to the sensor panel and configured to receive the output signal, the controller comprising a data bus and a plurality of devices communicatively coupled to the data bus;

an arbiter coupled to the data bus and configured to monitor bus access requests made by the plurality of devices; and

a clock module, coupled to the arbiter, and configured to provide a separate clock signal to each of the plurality of devices, wherein the clock module disables a clock signal applied to at least one device among the plurality of devices until the at least one device requires access to the bus.

25. The system of claim 24 wherein the plurality of devices comprises at least one primary device and at least one secondary device, wherein a clock frequency applied to the data bus is slowed when the at least one primary device has not requested access to the bus for the first predetermined length of time.

26. The system of claim 25 wherein the at least one primary device comprises a microcontroller.

27. The system of claim 25 wherein the at least one primary device comprises a channel scan logic module.

28. The system of claim 25 wherein the at least one primary device comprises a direct memory access controller.

29. The system of claim 25 wherein the clock module further disables a clock provided to the at least one secondary device when the at least one secondary device is not being accessed by the at least one primary device over the bus.

30. The system of claim 29 wherein the at least one secondary device comprises a boot ROM.

31. The system of claim 29 wherein the at least one secondary device comprises a serial peripheral interface.

32. A mobile telephone having touch surface interface, comprising:

a sensor panel configured to generate an output signal indicative of a touch or no-touch condition on the panel;

a controller coupled to the sensor panel and configured to receive the output signal, the controller comprising a data bus and a plurality of devices communicatively coupled to the data bus;

an arbiter coupled to the data bus and configured to monitor bus access requests made by the plurality of devices; and

a clock module, coupled to the arbiter, and configured to provide a separate clock signal to each of the plurality of devices, wherein the clock module reduces a clock frequency applied to the data bus if there are no bus access requests made by the plurality of devices for a first predetermined period of time.

33. A mobile telephone having touch surface interface, comprising:

a sensor panel configured to generate an output signal indicative of a touch or no-touch condition on the panel;

a controller coupled to the sensor panel and configured to receive the output signal, the controller comprising a data bus and a plurality of devices communicatively coupled to the data bus;

an arbiter coupled to the data bus and configured to monitor bus access requests made by the plurality of devices; and

a clock module, coupled to the arbiter, and configured to provide a separate clock signal to each of the plurality of devices, wherein the clock module disables a clock signal applied to at least one device among the plurality of devices until the at least one device requires access to the bus.

34. A digital audio player having a touch surface interface, comprising:

a sensor panel configured to generate an output signal indicative of a touch or no-touch condition on the panel;

a controller coupled to the sensor panel and configured to receive the output signal, the controller comprising a data bus and a plurality of devices communicatively coupled to the data bus;

an arbiter coupled to the data bus and configured to monitor bus access requests made by the plurality of devices; and

a clock module, coupled to the arbiter, and configured to provide a separate clock signal to each of the plurality of devices, wherein the clock module reduces a clock frequency applied to the data bus if there are no bus access requests made by the plurality of devices for a first predetermined period of time.

35. A digital audio player having a touch surface interface, comprising:

a sensor panel configured to generate an output signal indicative of a touch or no-touch condition on the panel;

a controller coupled to the sensor panel and configured to receive the output signal, the controller comprising a data bus and a plurality of devices communicatively coupled to the data bus;

an arbiter coupled to the data bus and configured to monitor bus access requests made by the plurality of devices; and

a clock module, coupled to the arbiter, and configured to provide a separate clock signal to each of the plurality of devices, wherein the clock module disables a clock signal applied to at least one device among the plurality of devices until the at least one device requires access to the bus.

36. A computer system, comprising:

means for providing output signals from a sensor panel to a controller, wherein the controller includes a data bus and a plurality of devices communicatively coupled to the data bus;

means for monitoring an activity level on the data bus by monitoring bus access requests by one or more of the plurality of devices; and

means for reducing a bus clock frequency if there is reduced or no activity on the bus for a first predetermined period of time.

37. A computer system, comprising:

means for providing output signals from a sensor panel to a controller, wherein the controller includes a data bus and a plurality of devices communicatively coupled to the data bus;

means for providing a separate clock signal to each of the plurality of devices;

means for monitoring bus access requests made by one or more of the plurality of devices; and

means for disabling a clock signal provided to a first device among the plurality of devices until the at least one device requires access to the bus.

38. A computer system, comprising:

means for monitoring an activity level on the data bus by monitoring bus access requests by one or more of the plurality of devices; and

means for reducing a bus clock frequency if there is reduced or no activity on the bus for a first predetermined period of time.

39. A computer system, comprising:

means for providing a separate clock signal to each of the plurality of devices;

means for monitoring bus access requests made by one or more of the plurality of devices; and

means for disabling a clock signal provided to a first device among the plurality of devices until the at least one device requires access to the bus.