Gated power management over a system bus

• US 8,405,617 B2
• Filed: 01/03/2007
• Issued: 03/26/2013
• Est. Priority Date: 01/03/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Wilson, Thomas James, Reeve, Richard James
• Primary Examiner(s): Wang, Quan-Zhen
• Assistant Examiner(s): NGUYEN, JENNIFER T
• Application Number:
  US11/650,202
• Publication Number:
  US 20080162967A1
• Time in Patent Office: 2,274 Days
• Field of Search: 345173-179, 345211-213, 713/322, 713/600, 178 1801- 1803
• US Class Current: 345/173
• 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 wherein a controller includes at least one primary device capable of being communicatively coupled to the data bus and a plurality of secondary devices capable of being communicatively coupled to the data bus, the at least one primary device capable of actively accessing the plurality of secondary devices by initiating actions and transmitting commands to the plurality of secondary devices, and the secondary devices capable of performing actions in response thereto, the method comprising:

providing scanned data output signals from a touch surface of the touch surface device to the controller;

comparing values of the scanned data to a threshold;

if the values of the scanned data exceed the threshold, terminating a low power mode of the controller and initiating a high power mode;

monitoring an activity level on the data bus by monitoring at least bus access requests by the at least one primary device ;

reducing a data bus clock frequency of the data bus if the data bus is inactive for a first predetermined period of time;

providing at least one clock signal to each of the plurality of second devices;

discontinuing providing the at least one clock signal to at least one of the secondary devices unless there is an active access to the at least one secondary device by the at least one primary device or the at least one secondary device is in use.

2. The method of claim 1 further comprising:

providing a clock signal to the at least one primary device;

reducing, but not turning off a clock frequency to the at least one primary device if there is reduced or no activity on the data bus from the at least one primary device.

3. The method of claim 2, wherein the clock frequency applied to the data bus is slowed when the at least one primary device has not requested access to the bus and there has been no activity on the data bus for a number of bus clock cycles.

4. The method of claim 3, wherein the number of bus clock cycles is a programmable number of bus clock cycles.

5. The method of claim 1, further including further reducing the data bus clock frequency of the data bus to a non-zero value if the data bus is inactive for a second predetermined period of time, greater than the first predetermined period of time.

6. A method of managing power in an integrated circuit having at least one primary device capable of being communicatively coupled to the data bus and a plurality of secondary devices capable of being communicatively coupled to the data bus, the at least one primary device capable of actively accessing the plurality of secondary devices by initiating actions and transmitting commands to the plurality of secondary devices, and the secondary devices capable of performing actions in response thereto, the method comprising:

providing scanned data output signals from a touch surface of the touch surface device to the controller;

comparing values of the scanned data to a threshold;

if the values of the scanned data exceed the threshold, terminating a low power mode of the controller and initiating a high power mode;

in the high power mode, monitoring an activity level on the data bus by monitoring at least bus access requests by the at least one primary device ;

reducing a data bus clock frequency of the data bus if the data bus is inactive for a first predetermined period of time;

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

turning off a clock frequency to at least one of the secondary devices unless there is an active access to the at least one secondary device by the at least one primary device or the at least one secondary device is in use.

7. A method of claim 6, further comprising:

providing a clock signal to the at least one primary device;

reducing, but not turning off a clock frequency to the at least one primary device if there is reduced or no activity on the data bus from the at least one primary device.

8. 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 at least one primary device capable of being communicatively coupled to the data bus and a plurality of secondary devices capable of being communicatively coupled to the data bus, the at least one primary device capable of actively accessing the plurality of secondary devices by initiating actions and transmitting commands to the plurality of secondary devices, and the secondary devices capable of performing actions in response thereto;

the sensor panel providing scanned data output signals from a touch surface of the sensor panel to the controller;

the controller operative for;

comparing values of the scanned data to a threshold; and

if the values of the scanned data exceed the threshold, terminating a low power mode of the controller and initiating a high power mode;

an arbiter coupled to the data bus and configured to monitor bus access requests made at least by the at least one primary device; and

a clock module, coupled to the arbiter, and configured to provide a separate clock signal to each of the at least one primary device and the plurality of secondary devices;

wherein the clock module;

reduces a data bus clock frequency of the data bus if the data bus is inactive for a first predetermined period of time; and

turns off a clock frequency to at least one of the secondary devices unless there is an active access to the at least one secondary device by the at least one primary device or the at least one secondary device is in use.

9. The system of claim 8 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.

10. The system of claim 9 wherein the at least one primary device comprises a microcontroller.

11. The system of claim 9 wherein the at least one primary device comprises a channel scan logic module.

12. The system of claim 9 wherein the at least one primary device comprises a direct memory access controller.

13. The system of claim 9 wherein the at least one secondary device comprises a boot ROM.

14. The system of claim 9 wherein the at least one secondary device comprises a serial peripheral interface.

15. 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 at least one primary device capable of being communicatively coupled to the data bus and a plurality of secondary devices capable of being communicatively coupled to the data bus, the at least one primary device capable of actively accessing the plurality of secondary devices by initiating actions and transmitting commands to the plurality of secondary devices, and the secondary devices capable of performing actions in response thereto;

the sensor panel providing scanned data output signals from a touch surface of the sensor panel to the controller;

the controller operative for;

comparing values of the scanned data to a threshold; and

if the values of the scanned data exceed the threshold, terminating a low power mode of the controller and initiating a high power mode;

an arbiter coupled to the data bus and configured to monitor bus access requests made at least by the at least one primary device; and

a clock module, coupled to the arbiter, and configured to provide a separate clock signal to each of the at least one primary device and the plurality of secondary devices;

wherein the clock module;

reduces a data bus clock frequency of the data bus if the data bus is inactive for a first predetermined period of time; and

turns off a clock frequency to at least one of the secondary devices unless there is an active access to the at least one secondary device by the at least one primary device or the at least one secondary device is in use.

16. 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 at least one primary device capable of being communicatively coupled to the data bus and a plurality of secondary devices capable of being communicatively coupled to the data bus, the at least one primary device actively capable of accessing the plurality of secondary devices by initiating actions and transmitting commands to the plurality of secondary devices, and the secondary devices capable of performing actions in response thereto;

the sensor panel providing scanned data output signals from a touch surface of the sensor panel to the controller;

the controller operative for;

comparing values of the scanned data to a threshold; and

if the values of the scanned data exceed the threshold, terminating a low power mode of the controller and initiating a high power mode;

an arbiter coupled to the data bus and configured to monitor bus access requests made at least by the at least one primary ; and

a clock module, coupled to the arbiter, and configured to provide a separate clock signal to each of the at least one primary device and the plurality of secondary devices;

wherein the clock module;

reduces a data bus clock frequency of the data bus if the data bus is inactive for a first predetermined period of time; and

turns off a clock frequency to at least one of the secondary devices unless there is an active access to the at least one secondary device by the at least one primary device or the at least one secondary device is in use.

17. A computer system, comprising:

means for providing output signals from a sensor panel to a controller, wherein the controller includes at least one primary device capable of being communicatively coupled to the data bus and a plurality of secondary devices capable of being communicatively coupled to the data bus, the at least one primary device actively capable of accessing the plurality of secondary devices by initiating actions and transmitting commands to the plurality of secondary devices, and the secondary devices capable of performing actions in response thereto;

the sensor panel providing scanned data output signals from a touch surface of the sensor panel to the controller;

the controller operative for;

comparing values of the scanned data to a threshold; and

if the values of the scanned data exceed the threshold, termininating a low power mode of the controller and initiating a high power mode;

means for monitoring an activity level on the data bus by monitoring bus access requests by at least the one primary device; and

means for providing a separate clock signal to each of the at least one primary device and the plurality of secondary devices;

wherein the clock module includes;

means for reducing a data bus clock frequency of the data bus if the data bus is inactive for a first predetermined period of time; and

means for turning off a clock frequency to at least one of the secondary devices unless there is an active access to the at least one secondary device by the at least one primary device or the at least one secondary device is in use.