Variable voltage detector power-up and power-down circuit for a joystick interface

• US 5,874,944 A
• Filed: 11/13/1996
• Issued: 02/23/1999
• Est. Priority Date: 11/13/1996
• Status: Expired due to Fees

• Current Assignee: VLSI Technology, Inc. (Koninklijke Philips N.V.)
• Original Assignee: VLSI Technology, Inc. (Koninklijke Philips N.V.)
• Inventors: Khoury, Elie Georges
• Primary Examiner(s): Wu, Daniel J.
• Application Number:
  US08/748,274
• Time in Patent Office: 832 Days
• Field of Search: 345/211, 345/212, 345/157, 345/156, 345/160, 345/161, 320/143, 320/161, 324/76.25, 324/76.11, 324/76.18
• US Class Current: 345/161
• CPC Class Codes: G06F 1/3215 Monitoring of peripheral devices
• CPC Class Codes: G06F 1/3259 Power saving in cursor control device, e.g. mouse, joystick, trackball
• CPC Class Codes: G06F 3/0383 Signal control means within the pointing device
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

There is provided herein a joystick interface which includes circuitry to detect when the joystick output signal has been at a steady-state level for a predetermined period of time and upon detection of that condition, the circuitry powers down at least some of the circuitry associated with providing the digital signal representation to the computer. In one particular embodiment of the invention, analog circuitry including a slope detector, makes use of two non-overlapping clocks to sample data and provide it to a comparator. The comparator is used to determine if there has been any change between consecutive or sequential samples, representative of joystick shaft movement. After a predetermined number of comparisons showing no change in either a neutral joystick position or a non-neutral joystick position, the digital circuitry is powered-down to a reduced power operating mode. Upon the detection of change between samples at any single comparator, a signal to return full power to the circuitry in the reduced power mode is provided.

Claims

1. An electronic joystick controller for use with a joystick including a positional shaft, said joystick generating at least a first signal corresponding to positional shaft movements along an X-axis or a Y-axis, said joystick controller comprising:

a processing circuit connected to the joystick to receive the first signal, said processing circuit for processing said first signal from said joystick, said processing circuit including a first reduced power operating mode and a second full power operating mode;

a controller additionally connected to the joystick to receive said first signal for receiving and sampling said first signal and for providing to said processing circuit a first controller output having (a) a first state if no change is detected between non-neutral shaft position value sequential samples and if no change is detected between neutral position value sequential samples and (b) a second state if change is detected between either at least two sequential non-neutral shaft postion value samples or sequential neutral and non-neutral shaft position value samples; and

wherein said processing circuit enters said reduced power mode upon receiving said first controller output of a first state and wherein said processing circuit enters said full power mode upon receiving said controller output of said second state.

2. An electronic controller, comprising:

at least one signal generator for providing a first signal;

a processing circuit connected to said at least one signal generator for processing said first signal from said generator;

a power supply connected to said processing circuit for powering said processing circuit;

a power down circuit connected between said processing circuit and said power supply for switching said processing circuit to one of a reduced power mode wherein said processing circuit uses a reduced amount of power and a power up mode wherein said processing circuit uses a greater amount of power sufficient to power said processing circuit for full operation of said processing circuit;

at least one detector in communication with said at least one signal generator for receiving said first signal, sampling said first signal and detecting change in at least two consecutive samples of said first signal, said at least one detector providing a detector output having a first detector state if no change is detected between non-neutral position value consecutive samples and having a second detector state if change is detected between at least two of said consecutive samples;

a counter in communication with said at least one detector to receive said detector output and to provide a counter output to said power down circuit, said counter output having a first counter state after a predetermined number of consecutive detector outputs of said first detector state are received, said counter output having a second counter state after receiving a detector output of said second detector state;

wherein said power down circuit is in said power down mode when said first counter state is received and wherein said power down circuit is in said power up mode when said second counter state is received.

3. The electronic controller of claim 2, wherein said detector additionally provides a detector output having a first detector state if no first signal is received from said at least one signal generator.

4. The electronic controller of claim 3, wherein said electronic controller comprises a joystick controller.

5. The electronic controller of claim 4, wherein said processing circuit includes an A/D converter.

6. The electronic controller of claim 5, wherein said at least one signal generator includes at least two signal generators and said at least one detector includes at least first and second detectors, and wherein each of said signal generators is in communication with one of said detectors.

7. The electronic controller of claim 6, wherein said at least first detector and said at least second detector comprise a first slope detector and a second slope detector, respectively.

8. The joystick and controller of claim 7, wherein said at least first slope detector comprises,

a first switch, including a first switch input and a first switch output, said first switch input being connected to receive said first signal, said first switch being normally open;

a second switch, including a second switch input and a second switch output, said second switch input being connected to receive said first signal, said second switch being normally open;

a comparator including a positive input and a negative input and a comparator output terminal, said positive input being connected to said first switch output, said negative input being connected to said second switch output;

a first storage capacitor connected between said first switch output and a reference level;

a second storage capacitor connected between said second switch output and a reference level;

a first clock for providing a continuous stream of first clock pulses;

a second clock for providing a continuous stream of second clock pulses;

wherein no clock pulse in said continuous stream of second clock pulses overlaps any clock pulse of said continuous stream of first clock pulses;

wherein each clock pulse from said continuous stream of first clock pulses causes said first switch to close for the duration of said each clock pulse from said continuous stream of first clock pulses and wherein each clock pulse from said continuous stream of second clock pulses causes said second switch to close for the duration of said each clock pulse from said continuous stream of second clock pulses; and

wherein the output of said comparator is high when said voltage at said positive input is greater than said voltage at said negative input and wherein the output of said comparator is low when the voltage at said positive input is less than or equal to the voltage at said negative input.

9. A joystick and controller, comprising:

a joystick including a positional shaft, said joystick generating at least a first signal corresponding to positional shaft movements along an X-axis and at least a second signal corresponding to positional shaft movements along a Yaxis, said joystick providing said at least first and second signals to a processing circuit;

a processing circuit connected to said joystick for processing said first and said second signals from said joystick, said processing circuit including an A/D converter;

a power supply connected to said processing circuit for powering said processing circuit;

a power down circuit connected between said processing circuit and said power supply for switching said processing circuit to one of a power down mode wherein said processing circuit uses a reduced amount of power and a power up mode wherein said processing circuit uses a greater amount of power sufficient to power said processing circuit for full operation of said processing circuit;

at least a first detector in communication with said joystick to receive said first signal, sampling said first signal and detecting change in consecutive samples of said first signal, said first detector providing a first detector output having a first detector state if no change is detected between non-neutral value consecutive samples and if no change is detected between neutral value consecutive samples and having a second detector state if change is detected between said consecutive samples;

at least a second detector in communication with said joystick to receive said second signal, sampling said second signal and detecting change in consecutive samples of said second signal, said second detector providing a second detector output having a first detector state if no change is detected between non-neutral value consecutive samples and if no change is detected between neutral value consecutive samples and having a second detector state if change is detected between said consecutive samples;

a counter block in communication with said at least first and second detectors to receive said first and second detector outputs and to provide a counter output to said power down circuit, said counter output having a first counter state after a predetermined number of consecutive detector outputs of said first detector state are received from both said at least first and second detectors, said counter output having a second counter state after receiving a detector output of said second detector state from either of said at least first and second detectors;

wherein said power down circuit is in said power down mode when said first counter state is received and wherein said power down circuit is in said power up mode when said second counter state is received.

10. The joystick and controller of claim 9, wherein said at least first detector and said at least second detector comprise a first slope detector and a second slope detector, respectively.

11. The joystick and controller of claim 10, wherein said first slope detector comprises,

a first switch, including a first switch input and a first switch output, said first switch input being connected to receive said first signal, said first switch being normally open;

a second switch, including a second switch input and a second switch output, said second switch input being connected to receive said first signal, said second switch being normally open;

a comparator including a positive input and a negative input and a comparator output terminal, said positive input being connected to said first switch output, said negative input being connected to said second switch output;

a first storage capacitor connected between said first switch output and a reference level;

a second storage capacitor connected between said second switch output and a reference level;

a first clock for providing a continuous stream of first clock pulses;

a second clock for providing a continuous stream of second clock pulses;

wherein no clock pulse in said continuous stream of second clock pulses overlaps any clock pulse of said continuous stream of first clock pulses;

wherein each clock pulse from said continuous stream of first clock pulses causes said first switch to close for the duration of said each clock pulse from said continuous stream of first clock pulses and wherein each clock pulse from said continuous stream of second clock pulses causes said second switch to close for the duration of said each clock pulse from said continuous stream of second clock pulses; and

wherein the output of said comparator is high when said voltage at said positive input is greater than said voltage at said negative input and wherein the output of said comparator is low when the voltage at said positive input is less than or equal to the voltage at said negative input.

12. The joystick and controller of claim 10,

wherein said joystick and controller includes a second joystick, wherein said second joystick generates a third signal corresponding to positional shaft movement along a x axis and a fourth signal corresponding to positional shaft movement along a y axis,

wherein said joystick and controller includes a third analog slope detector to receive said third signal, sample said third signal and detecting change in consecutive samples of said third signal, said third detector providing a third detector output having a first detector state if no change is detected between at least two non-neutral position value consecutive samples and if no change is detected between neutral value consecutive samples and having a second detector state if change is detected between at least two said consecutive samples, and

wherein said joystick and controller includes a fourth analog slope detector to receive said fourth signal, sample said fourth signal and detecting change in consecutive samples of said fourth signal, said fourth detector providing a fourth detector output having a first detector state if no change is detected between non-neutral position value consecutive samples and if no change is detected between neutral position value consecutive samples and having a second detector state if change is detected between at least two of said consecutive samples.

13. The joystick and controller of claim 12, wherein said counter block includes an or gate and a clock driven counter including a reset input and an output, wherein said first, second, third and fourth detector outputs are provided to the inputs of said or gate and the output of said or gate is provided to said reset input of said counter, whereby a high state output from said or gate resets said counter, and wherein said output of said clock driven counter goes to a high state when said counter reaches a predetermined count.

14. A slope detector, comprising:

a variable voltage source;

a first switch, including a first switch input and a first switch output, said first switch input being connected to said variable voltage source, said first switch being normally open;

a second switch, including a second switch input and a second switch output, said second switch input being connected to said variable voltage source, said second switch being normally open;

a comparator including a positive input and a negative input and a comparator output terminal, said positive input being connected to said first switch output, said negative input being connected to said second switch output;

a first storage capacitor connected between said first switch output and a reference level;

a second storage capacitor connected between said second switch output and a reference level;

a first clock for providing a continuous stream of first clock pulses;

a second clock for providing a continuous stream of second clock pulses;

wherein no clock pulse in said continuous stream of second clock pulses overlaps any clock pulse of said continuous stream of first clock pulses;

wherein each clock pulse from said continuous stream of first clock pulses causes said first switch to close for the duration of said each clock pulse from said continuous stream of first clock pulses and wherein each clock pulse from said continuous stream of second clock pulses causes said second switch to close for the duration of said each clock pulse from said continuous stream of second clock pulses; and

wherein the output of said comparator is high when said voltage at said positive input is greater than said voltage at said negative input and wherein the output of said comparator is low when the voltage at said positive input is less than or equal to the voltage at said negative input.

15. The slope detector of claim 14, wherein said slope detector is used in a joystick interface, wherein said slope detector is used to detect relative change in joystick output over time.