System for distributed power management in portable computers

• US 5,423,045 A
• Filed: 04/15/1992
• Issued: 06/06/1995
• Est. Priority Date: 04/15/1992
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Sharma, Vikram, Jones, Christopher D., Lee, Nathan J., Kannan, Krishnamurthi, Novak, Frank P., Leontiades, Kyriakos
• Primary Examiner(s): MacDonald, Allen R.
• Assistant Examiner(s): DAVIS, GEORGE B
• Application Number:
  US07/870,124
• Time in Patent Office: 1,147 Days
• Field of Search: 395/750, 395/200, 364/707, 364/200, 365/229, 371/9.1
• US Class Current: 713/322
• CPC Class Codes: G06F 1/30 Means for acting in the event of power-supply failure or interruption, e.g. power-supply fluctuations for resetting only G06F1/24
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 9/30083 Power or thermal control instructions

Abstract

A provides a system and method for managing power in a portable, pen-based notebook computer. The system and method provides a means for minimizing power consumption by collecting and interpreting power related data of various processing elements while hiding many of the details from the end-user. The system monitors, collects, and acts, upon power-related data in a portable computer to maximize the amount of time the portable computer can be used between battery re-charging with minimal user intervention. The system has a plurality of independently controllable power planes and a plurality of central processing units (CPUs) operating asynchronously with respect to each other. The present invention is further comprised of an on/off glue logic means for monitoring battery condition, user invoked functions, and system state and a power management means for controlling the operation of each of the CPUs as a function of the conditions sensed by a sensing means.

Claims

1. A system for monitoring, collecting and acting upon power-related data in a portable computer to maximize an amount of time the portable computer can be used between the recharging of a battery with minimal user intervention, the portable computer having a user interface and a perceived state of operation, the system comprising:

a plurality of independently controllable power planes

a plurality of central processing units (CPUs), coupled to said plurality of independently controllable power planes, operating asynchronously with respect to each other to selectively control application of power to said plurality of independently controllable power planes, each of said plurality of CPUs performing power management functions, said plurality of CPUs including;

a main processor having a first set of multiple operational states, said main processor controlling said plurality of independently controllable power planes, whereby a present state of said main processor determines the perceived state of operation of the portable computer,

a service processor, coupled to said main processor, having a second set of multiple operational states, said service processor configured to manage peripheral devices, and

a battery microcontroller configured to manage power input from one or more power sources coupled to the portable computer, said power sources including a battery having a temperature and a voltage, said battery microcontroller comprising a battery processor having a third set of multiple operational states; and

power management means for controlling the operation of each of said plurality of CPUs as a function of power availability, processing requirements, system activity and status of an on/off button.

2. The system of claim 1, wherein the portable computer further comprises:

one or more peripheral devices, and

one or more interfaces corresponding with each of said one or more peripheral devices; and

wherein said plurality of independently controllable power planes comprises;

a core power plane, comprising;

said service processor,

a core chip set configured to perform power control functions, core chip set providing logical compatibility with an IBM PC/AT standard computer, and

glue logic means for monitoring, processing, and reporting system condition changes which may affect power consumption;

a main processor power plane comprising said main processor;

a miscellaneous power plane comprising communication buses and associated logic and

a plurality of interface power planes, each of said interface power planes controlling the power related to a respective one of said one or more peripheral devices or said one or more interfaces.

3. The system of claim 2, wherein said first set of multiple operational states comprises:

a first zero power state wherein all power is removed from the portable computer except for said battery microcontroller;

a first normal power state wherein the portable computer is fully powered and operational;

a first idle power state wherein said main processor operates at a slower processing speed; and

a first standby power state wherein only those system components which are necessary to preserve data are powered, and wherein user interactive devices are not powered, thereby setting said perceived state of operation of the portable computer to power off.

4. The system of claim 3, wherein said second set of multiple operational states, comprises:

a second zero power state wherein said service processor does not receive power;

an initial diagnostic power state wherein said service processor performs a diagnostic check on said peripheral devices;

a second normal power state wherein said service processor responds to commands from said main processor and acquires the power-related data from said battery microcontroller;

a second idle power state wherein said service processor ceases executing instructions while maintaining only a service processor clock; and

a power check state wherein said service processor monitors said battery microcontroller to receive status data regarding said one or more power sources.

5. The system of claim 4, wherein said power management means includes a main processor control means, said main processor control means comprising:

restoring means for restoring application program states and applications program data of an application program when said main processor transitions to said first normal power state from said first zero power state, thereby resulting in a restored application program state and data, said restored application program state and application data being equivalent to said application program state and said application program data prior to said main processor entering said first zero power state;

refreshing means for refreshing the user interface when said main processor transitions from said first zero power state to said first normal power state, the user interface being equivalent to the user interface prior to said main processor entering said first zero power state; and

automatic applications saving means for automatically saving said application program state and said application program data in a secondary storage medium when said main processor enters said first standby power state.

6. The system of claim 5, wherein said main processor control means further comprises:

determination means for determining portable computer power consumption for each of said first set of multiple operational states;

prioritization means for determining which of said first set of multiple operational states can support said particular function and for further determining which of said first set of multiple operational states has a power consumption which is lowest in value, said determination means comprising;

first normal power state activity determination means for determining when said main processor has completed all necessary processing functions which require said main processor to remain fully powered and operational, said first main processor having completed all of said necessary processing functions which require said main processor to remain fully powered and operational when said first main processor executes an idle thread, whereby said execution of said idle thread causes said main processor control means to immediately transition said main processor from said first normal power state to said first idle power state,

interrupt processing means for transitioning said main processor from said first idle power state to said first normal power state to process an interrupt and for immediately transitioning said main processor from said first normal power state to said first idle power state after said main processor executes said interrupt,

first idle power state activity determination means for transitioning said main processor from said first idle power state to said first standby power state through said first normal power state when there is no processing activity for a first idle power state time duration, said first idle power state time duration defaulting to a first idle power state time duration default value when said first idle power state time duration is not selected by the user, and

standby state activity determination means for removing power from the portable computer upon expiration of a standby power state time duration, said expiration of said first standby power state time duration resulting in said main processor control means transitioning said main processor from said first standby power state to said first zero power state through said first normal power state, said first standby power state time duration defaulting to a first standby power state time duration default value when said first standby power state time duration is not selected by the user.

7. The system of claim 6, wherein said main processor operates at a clock speed, and further wherein said main processor control means comprises:

main processor clock control means for reducing said clock speed of said main processor when said main processor enters said first idle power state;

LCD backlight control means for turning off an LCD backlight part of the user interface when said main processor has remained in said first idle power state continuoulsy for a predetermined amount of time, whereby the user interface has a reduced, yet readable clarity; and

VGA controller power reduction means for placing a VGA controller in a low-power mode of operation when said main processor enters said first standby power state, wherein said VGA controller permits refreshing of a video memory at a reduced rate.

8. The system of claim 7, wherein said main processor control means further comprises a power management interrupt handler means for processing power management interrupts, said power management interrupt handler means comprising:

power management interrupt assignment means for determining if a power management event shall cause a power management interrupt in each of said first set of multiple operational states;

power management interrupt cause determination means for determining which of said power management events and which of said system condition changes has caused said power management event; and

on/off button de-latching means for releasing the on/off button when a user-invoked power change system request occurs when said main processor is in said first normal power state and in said first idle power state.

9. The system of claim 8, wherein said main processor makes a transition between said first set of multiple operational states due to an occurrence of a power management event, wherein said power management event is caused by an occurrence of one or more system condition changes, said system condition changes comprising:

a battery warning condition indicating a low battery voltage, said low battery voltage having a value such that said portable computer cannot perform said particular function;

an external source present condition indicating an external DC power source is present and the portable computer is no longer dependent on the battery;

an excessive battery temperature condition indicating said battery has a temperature sufficient to cause potential damage to said battery;

an excessive ambient temperature condition indicating that said temperature of said independently controllable power planes is excessively high due to excessive or abnormal power consumption;

a battery charge fault condition indicating said battery controller has detected an excessive voltage condition, the battery was removed during charging, and/or the battery temperature became excessive during charging; and

one or more system request conditions, each of said one or more system request conditions indicating a processing demand has been placed on the portable computer.

10. The system of claim 9, wherein said main processor control means further comprises a resume means for restoring said main processor to said first normal power state from said first standby power state to process said one or more system request conditions, said resume means comprising:

on/off button press system request resume means for restoring full power to the portable computer when the on/off button is pressed, comprising;

low battery charge processing means for providing the user with an indication of said battery warning condition and for preventing said main processor from transitioning to said first normal power state when said battery warning condition is present, and

interface power plane power restoration means for restoring power to said plurality of interface power planes;

modem call system request resume means for invoking a requested one or more of said application program without restoring power to the user interface; and

timer interrupt system request resume means for executing one or more scheduled tasks without restoring power to the user interface.

11. The system of claim 10, wherein said user interface further comprises an integrated LCD panel and digitizer operatively coupled to said independently controllable power planes, wherein said plurality of CPUs, said power management means, said integrated LCD panel and said digitizer are packaged to resemble a notebook with a writing surface, said integrated LCD panel having separate LCD screen and LCD backlight controls.

12. The system of claim 11, wherein said core chip set comprises a plurality of register files programmed to enable said main processor to perform power management functions, said register files comprising:

a power down control register (PDCR) programmed to power down said main processor or the complete system;

a CPU clock control register (CCCR) programmed to adjust the clock speed of said main processor;

a refresh control register (RCR) programmed to adjust the rate at which the system random access memory (RAM) is refreshed;

a power plane control register (PPCR) programmed to control the power to a plurality of said independently controllable power planes;

screen timer control registers (STCRs) programmed to control the time for which said LCD panel and said backlight will be powered when there is no activity on the system;

a power management interrupt mask register (PYMIMR) programmed to control under which states of said main processor, said power management events will generate a power management interrupt;

a power management interrupt status register (PMISR) programmed with said power management events which caused latest one of said power management interrupt; and

a power management event register (PMEVR) programmed to contain a historical file of the occurrence of said power management events.

13. The system of claim 9, wherein said system request conditions comprise:

a modem call system request generated by a modem call;

a timer interrupt system request generated by an expiration of a time-out value in said main processor; and

a user-invoked power change system request generated by pressing the on/off button.

14. The system of claim 13, wherein said glue logic means, comprises a monitoring means for monitoring said system condition changes and for monitoring the present state of said main processor, said monitoring means comprising:

first monitoring means for monitoring a low battery signal representing said battery warning condition;

second monitoring means for monitoring a timer interrupt signal representing said timer interrupt system request;

third monitoring means for monitoring a ring indicator condition signal representing said modem call system request;

fourth monitoring means for monitoring an on/off button state signal representing state of said user invoked power change system request; and

fifth monitoring means for monitoring a full power down signal representing said main processor being in said first standby power state.

15. The system of claim 14, wherein said second set of multiple operational states, comprises:

a second zero power state wherein said service processor does not receive power;

an initial diagnostic power state wherein said service processor performs a diagnostic check on said peripheral devices;

a second normal power state wherein said service processor responds to commands from said main processor and acquires the power-related data from said battery microcontroller;

a second idle power state wherein said service processor ceases executing instructions while maintaining only a service processor clock; and

a power check state wherein said service processor monitors said battery microcontroller to receive status data regarding said one or more power sources.

16. The system of claim 15, wherein said power management events comprise:

a suspend power management event occurring when said battery warning condition occurs while said main processor is in said first normal power state and/or said first idle power state;

a resume power management event occurring when said system request condition occurs while said main processor is in said first standby power state; and

a power control unit power management event occurring when said system request condition and said battery warning condition occur simultaneously, said power control unit power management event also occurring when said main processor is in said first normal power state and/or said first idle power state and said user-invoked power change system request occurs.

17. The system of claim 16, wherein said glue logic means further comprises a generation means for generating a plurality of power management signals as a function of said monitoring means, said power management signals comprising:

a resume power management signal representing an occurrence of said resume power management event;

a suspend power management signal representing an occurrence of said suspend power management event; and

a SPIRQ power management signal representing an occurrence of said user-invoked power change system request while said main processor is not in said first standby power state, and representing a simultaneous occurrence of said system request condition and said battery warning condition.

18. The system of claim 17, wherein said service processor further comprises:

a low battery output configured to enable said glue logic means to generate said SPIRQ power management signal and said suspend power management signal; and

a SPIRQ power managment input configured to receive said SPIRQ power management signal.

19. The system of claim 18, wherein said power management means includes a battery microcontroller control means, said battery microcontroller control means comprising:

detecting means for detecting an availability of said external DC power source and for charging said battery;

power supply means for supplying power to said main processor, said service processor, and one or more of said independently controllable power planes when said on/off button is pressed; and

battery monitor means for monitoring battery condition and also for generating an alarm to said service processor to prevent battery damage and to signal a shutdown of the portable computer.

20. The system of claim 16, wherein said main processor further comprises,

a first data input configured to receive data from said service processor;

a first data output configured to transmit service processor commands and data requests to said service processor;

a power control unit input configured to receive an indication of said power control unit power management event; and

a full power down output configured to transmit said full power down signal.

21. The system of claim 20, wherein said service processor commands comprise a query power environment command having a first parameter byte, said first parameter byte comprising:

a power management reason code request,

a power status data request comprising a battery type, battery capacity, and a power distribution indication status;

a battery voltage data request indicating said battery voltage;

a system load data request indicating portable computer power consumption;

a battery temperature data request indicating said battery temperature; and

an ambient temperature data request indicating the temperature of said independently controllable power planes.

22. The system of claim 21, wherein said service processor commands further comprise a send command byte to said battery microcontroller, said send command byte having a second parameter byte, said second parameter byte comprising:

a clear power disrupted indication request, said clear power disrupted indication indicating when continuity of said power input has been disrupted, said continuity established by signature bytes, said signature bytes located in said dynamic RAM in said battery microcontroller, said signature bytes becoming invalid with an interruption in said power input; and

a clear charge fault indication request indicating when said excessive battery temperature condition and/or said battery charge fault condition occurs.

23. The system of claim 22, wherein said service processor comprises:

a full power down input coupled to said full power down output and configured to determine when said service processor is to transition from said second normal power state to said second idle power state;

a power control unit output coupled to said power control unit input and configured to transmit an indication of said power control unit power management event to said main processor;

a second data input coupled to said first data output and configured to receive commands and data requests from said main processor; and

a second data output coupled to said first data input and configured to receive said service processor commands.

24. The system of claim 23, wherein said service processor further

a wakeup output configured to command said battery microcontroller to transition from said third idle power state to third normal power state;

a third data input configured to receive power source status data from said battery microcontroller;

a third data output configured to transmit battery microcontroller commands to said battery microcontroller; and

clock control means configured to control data transfers between said service processor and said battery microcontroller.

25. The system of claim 24, wherein said battery microcontroller commands comprise:

a turn off power command configured to remove power from the portable computer;

a clear power disrupted indication command determined from said clear power disrupted indication request received from said main processor; and

a clear charge fault indication command determined from said clear charge fault indication request received from said main processor.

26. The system of claim 25, wherein said service processor control means comprises:

diagnostic means for performing diagnostics on said peripheral devices controlled by said service processor, said diagnostics occurring when said service processor enters said initial diagnostic power state;

power conservation means for transitioning said service processor to said second idle power state when there has been no activity on the portable computer, said power conservation means ceasing all processing and maintaining said service processor clock, said power conservation means periodically collecting battery-related data from said battery microcontroller by momentarily transitioning said service processor from said second idle power state to said power check state; and

a battery microcontroller management means for managing said battery microcontroller as a function of commands received from said main processor.

27. The system of claim 4, wherein said third set of multiple operational states comprises:

a third zero power state wherein all of said one or more power sources are absent;

a third normal power state wherein said battery microcontroller performs an initialization routine if entered from said third zero power state;

a third idle power state wherein said battery microcontroller consumes minimal power; and

a second standby power state, wherein said battery microcontroller consumes a minimum amount of power to detect a change of state of said on/off button and to maintain data in a dynamic RAM.

28. The system of claim 1, wherein said third set of multiple operational states comprises:

a third zero power state wherein all of said one or more power sources are absent;

a thrid normal power state wherein said battery microcontroller performs an initialization routine if entered from said third zero power state;

a third idle power state wherein said battery microcontroller consumes minimal power; and

a second standby power state, wherein said battery microcontroller consumes a minimum amount of power to detect a change of state of said on/off button and to maintain data in a dynamic RAM.