Method and apparatus for calibrating a resistive ladder switching matrix
First Claim
1. A method for calibrating a resistive ladder switching matrix coupled to a keypad in a portable electronic device having a housing with a cover that may be positioned in an open state or a closed state, comprising the steps of:
- coupling a first contact of a calibration element to a reference voltage by moving the cover from the open state to the closed state;
when the first contact of the calibration element is coupled to the reference voltage and a second contact of the calibration element is coupled to ground, determining a calibration resistance across the calibration element; and
calibrating signals from the resistive ladder switching network when the cover is in the closed state in accordance with the calibration resistance.
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Accused Products
Abstract
A method and apparatus for calibrating a resistive ladder switching matrix coupled to a keypad in a portable electronic device having a housing with a cover that may be positioned in an open state or a closed state. A first contact of a calibration element is coupled to a reference voltage and a second contact of the calibration element is coupled to ground by moving the cover from the open state to the closed state. When the first contact of the calibration element is coupled to the reference voltage and the second contact of the calibration element is coupled to ground, a calibration resistance across the calibration element is determined. The calibration resistance may correspond to an input impedance of the resistive ladder switching matrix when no buttons associated with the keypad are depressed. Signals from the resistive ladder switching network are calibrated when the cover is in the closed state in accordance with the calibration resistance.
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Citations
24 Claims
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1. A method for calibrating a resistive ladder switching matrix coupled to a keypad in a portable electronic device having a housing with a cover that may be positioned in an open state or a closed state, comprising the steps of:
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coupling a first contact of a calibration element to a reference voltage by moving the cover from the open state to the closed state;
when the first contact of the calibration element is coupled to the reference voltage and a second contact of the calibration element is coupled to ground, determining a calibration resistance across the calibration element; and
calibrating signals from the resistive ladder switching network when the cover is in the closed state in accordance with the calibration resistance. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for calibrating a resistive ladder switching matrix coupled to a keypad in a portable electronic device having a housing with a cover that may be positioned in an open state or a closed state, comprising the steps of:
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coupling a first contact of a calibration element to ground by moving the cover from the open state to the closed state;
when the first contact of the calibration element is coupled to ground and a second contact of the calibration element is coupled to reference voltage, determining a calibration resistance across the calibration element; and
calibrating signals from the resistive ladder switching network when the cover is in the closed state in accordance with the calibration resistance. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method for calibrating a resistive ladder switching matrix coupled to a keypad in a portable electronic device having a housing with a cover that may be positioned in an open state or a closed state, comprising the steps of:
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coupling a first contact of a calibration element to a reference voltage and a second contact of the calibration element to ground by moving the cover from the open state to the closed state;
when the first contact of the calibration element is coupled to the reference voltage and the second contact of the calibration element is coupled to ground, determining a calibration resistance across the calibration element; and
calibrating signals from the resistive ladder switching network when the cover is in the closed state in accordance with the calibration resistance. - View Dependent Claims (14, 15, 16, 17, 18)
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19. An apparatus for calibrating a resistive ladder switching matrix coupled to a keypad in a portable electronic device having a housing with a cover that may be positioned in an open state or a closed state, comprising:
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a calibration element having a first contact coupled to a reference voltage and a second contact coupled to ground when the cover is in the closed state, wherein the first contact is detached from the reference voltage and the second contact is detached from ground when the cover is in the open state;
a microprocessor that determines a calibration resistance across the calibration element when the cover is in the closed state and calibrates signals from the resistive ladder switching network when the cover is in the closed state in accordance with the calibration resistance. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification