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Touch screen power control in a computer system

  • US 5,553,296 A
  • Filed: 02/17/1995
  • Issued: 09/03/1996
  • Est. Priority Date: 05/28/1993
  • Status: Expired due to Fees
First Claim
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1. A method for selectively and interactively controlling the supply of power to a battery-powered computer system by means of a finite-state machine, said computer system comprising a central processing unit (CPU) coupled to a touch screen controller which controls a touch sensitive display screen, said method comprising the steps of:

  • a. responsive to a reset signal, transitioning said touch screen controller to a reset state;

    b. operative when said touch screen controller is in said reset state, transitioning said touch screen controller to a second state;

    c. operative when said touch screen controller is in said second state, setting an internal full power on mode flag and transitioning said touch screen controller to a first decision state;

    d. operative when said touch screen controller is in said first decision state, checking for a first touch input from said touch sensitive display screen;

    operative when said first touch input is present, transitioning said touch screen controller to a transfer state; and

    operative when said first touch input is not present, transitioning said touch screen controller to a second decision state;

    e. operative when said touch screen controller is in said transfer state, interrupting said CPU, transferring the X, Y, and Z coordinates of said first touch input to said CPU, and transitioning said touch screen controller back to said first decision state;

    f. operative when said touch screen controller is in said second decision state, checking for the assertion of a soft power signal;

    operative when said soft power signal is not asserted, transitioning said touch screen controller back to said first decision state; and

    operative when said soft power signal is asserted, transitioning said touch screen controller to a shutdown state;

    g. operative when said touch screen controller is in said shutdown state, setting an internal power down mode flag, deasserting a power on signal, transitioning said touch screen controller to a third decision state;

    h. operative when said touch screen controller is in said third decision state, checking for a second touch input and, operative when said second touch input is present, transitioning to a power-up state;

    i. operative when said touch screen controller is in said power-up state, asserting said power on signal.

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