System for providing electrical power to a computer input device according to the interface types through the shared use of wires and a voltage clamp

• US 5,920,734 A
• Filed: 06/21/1996
• Issued: 07/06/1999
• Est. Priority Date: 02/01/1996
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Holmdahl, Todd E.
• Primary Examiner(s): Lee, Thomas C.
• Assistant Examiner(s): Ton, David
• Application Number:
  US08/667,402
• Time in Patent Office: 1,110 Days
• Field of Search: 361/686, 361/601, 326/77, 701/215, 345/157, 395/893, 395/882, 395/884, 395/892, 395/309, 178/19.01, 379/93.05, 323/313, 358/400
• US Class Current: 710/73
• CPC Class Codes: G06F 3/0383 Signal control means within the pointing device

Abstract

A system permits the shared use of lines in a cursor control device coupled to a PS/2 interface or a serial interface. A computer pointing device such as a mouse can be coupled to either the PS/2 interface or the serial interface. The current supplied by the serial interface is limited by conventional circuitry within the interface itself. However, a clock line, normally used when the pointing device is coupled to the PS/2 interface, can be used to supply additional current to the pointing device when coupled to a serial interface. A Schottky diode is coupled in series between a V_cc /RTS line and a power supply node within the pointing device. A second Schottky diode is coupled from a CLK/DTR line to the power supply node. When the pointing device is coupled to the PS/2 interface, the first Schottky diode provides current from a V_cc source within the PS/2 interface. The second Schottky diode is not active when the pointing device is coupled to the PS/2 interface. When the pointing device is coupled to the serial interface, both the first and second Schottky diodes are active and both supply current to the power supply node. The first Schottky diode also prevents reverse current flow during initialization of the serial interface.

Claims

1. A system to provide electrical power to a computer input device through a wire cable alternatively couplable to an interface having one of a first interface type or a second interface type, the system comprising:

a first wire in the wire cable to carry electrical power to the computer input device;

a second wire in the wire cable to carry a first signal if the computer input device is coupled to the first interface type and to carry additional electrical power to the computer input device if the computer input device is coupled to the second interface type; and

a voltage clamp coupled between said first and second wires in the wire cable, said voltage clamp permitting said additional electrical power to be coupled to said first wire if the computer input device is coupled to the second interface type and preventing said first signal from being coupled to said first wire if the computer input device is coupled to the first interface type.

2. The system of claim 1 wherein said voltage clamp is a diode coupled between said first and second wires.

3. The system of claim 2 wherein said diode is a Schottky diode.

4. The system of claim 1 wherein the first interface type is a PS/2 interface and said second interface type is a serial interface, the computer input device further including a clock generator generating a clock signal on said second wire as said first signal when the cursor controller is coupled to the PS/2 interface and carrying said additional power to the computer input device when connected to the serial interface.

5. The system of claim 1 wherein said first wire carries said electrical power at a first voltage level when the computer input device is coupled to the first interface type and carries said electrical power at a second voltage level when the computer input device when connected to the second interface type, the system further including a voltage regulator to regulate said first and second voltage levels to a predetermined voltage level.

6. The system of claim 1 wherein said first interface type is a PS/2 interface and said second interface type is a serial interface, said first wire carrying said electrical power at a first voltage level when the computer input device is coupled to the PS/2 interface and carrying said electrical power at a second voltage level higher than said first voltage level when the computer input device is coupled to the serial interface, said second wire carrying said first signal at said first voltage level when the cursor controller is coupled to the PS/2 interface and carrying said additional electrical power at said second voltage level higher than said first voltage level when the computer input device is coupled to the serial interface, said voltage clamp being activated by said second voltage to couple said additional electrical power to said first wire when the computer input device is coupled to the serial interface and remaining inactive to block said first signal when the computer input is coupled to the PS/2 interface.

7. The system of claim 6, further including a clock generator generating a clock signal on said second wire as said first signal when the computer input is coupled to the PS/2 interface and carrying said additional power to the computer input device when connected to the serial interface.

8. The system of claim 1 wherein said voltage clamp is coupled to a power supply node and is coupled to said first wire at a power input terminal, the system further including a current limiting device coupled between said power input terminal and said power supply node to limit a flow of electrical current thereto.

9. The system of claim 8 wherein said current limiting device is a transistor.

10. The system of claim 1 for use with data displayed on a display device, the system further including:

a first encoder circuit to generate a first set of electrical signals corresponding to user manipulation of the computer input device to move the cursor in a first direction on the display device;

a second encoder circuit to generate a second set of electrical signals corresponding to user manipulation of the computer input device to move the cursor in a second direction on the display device orthogonal to said first direction on the display device; and

a third encoder circuit to generate a third set of electrical signals corresponding to user manipulation of the computer input device to alter the display of data displayed on the display device with said additional electrical power providing electrical power for at least a portion of one of said first, second, and third encoder circuits.

11. A system for the shared use of lines in a computer input device alternatively coupled to an interface having a first or second interface type in a computer by a wire cable, the wire cable containing a power wire to provide electrical power to the computer input device when coupled to the first interface type and the second interface type, the system comprising:

a first wire in the wire cable to carry a first signal having a first signal type if the computer input device is coupled to the first interface type and to carry a second signal having a second signal type if the computer input device is coupled to the second interface, the first signal type being compatible for operation with the first interface type and the second signal type being compatible for operation with the second interface type;

a second wire in the wire cable to provide a reference voltage; and

a voltage clamp coupled between said first wire and said second wire to thereby limit a voltage of said first signal.

12. The system of claim 11 for use with data displayed on a display device wherein said second signal is additional electrical power to the computer input device when coupled to the second interface type, the system further including:

a first encoder circuit to generate a first set of electrical signals corresponding to user manipulation of the computer input device to move the cursor in a first direction on the display device;

a second encoder circuit to generate a second set of electrical signals corresponding to user manipulation of the computer input device to move the cursor in a second direction on the display device orthogonal to said first direction on the display device; and

a third encoder circuit to generate a third set of electrical signals corresponding to user manipulation of the computer input device to alter the display of data displayed on the display device with said additional electrical power providing electrical power for at least a portion of one of said first, second, and third encoder circuits.

13. The system of claim 12 wherein the computer input device is a mouse having a rotatable encoder ball that rotates in response to user movement of the mouse and said first and second encoder circuits encode said ball rotation in two orthogonal directions.

14. A system to provide electrical power to a three dimensional computer input device through a wire cable alternatively couplable to an interface having one of a first interface type or a second interface type, the system comprising:

a first wire in the wire cable to carry electrical power to the computer input device;

a second wire in the wire cable to carry a first signal if the computer input device is coupled to the first interface type and to carry additional electrical power to the computer input device if the computer input device is coupled to the second interface type;

a voltage clamp coupled between said first and second wires in the wire cable to permit said additional electrical power to be coupled to said first wire if the computer input device is coupled to the second interface type and to prevent said first signal from being coupled to said first wire if the computer input device is coupled to the first interface type;

first and second encoder circuits to generate a set of electrical signals corresponding to user manipulation of the computer input device to move the cursor in first and second orthogonal directions on the display device; and

a third encoder circuit to generate a set of electrical signals corresponding to user manipulation of the computer input device in a manner independent of user manipulation associated with said first and second encoder circuits with said additional electrical power providing electrical power for at least a portion of one of said first, second, and third encoder circuits when coupled to the second interface type.

15. A method for the shared use of lines in a computer input device alternatively coupled to an interface having a first or second interface type in a computer by a wire cable, the wire cable containing a power wire to provide electrical power to the computer input device when coupled to the first interface type and the second interface type, the method comprising the steps of:

coupling a first signal having a first signal type to a first wire in the wire cable if the computer input device is coupled to the first interface type and coupling a second signal having a first signal type to said first wire if the computer input device is coupled to the second interface type, the first signal type being compatible for operation with the first interface type and the second signal type being compatible for operation with the second interface type;

providing a reference voltage on a second wire in the wire cable; and

limiting a voltage on said first wire to couple said first signal to said second wire if the computer input device is coupled to the first interface type and to block the second signal from the first wire when the computer input device is coupled to the second interface type.

16. The method of claim 15 for use with data displayed on a display device wherein said second signal is additional electrical power to the computer input device when coupled to the second interface type, the method further including the steps of:

generating a first set of electrical signals corresponding to user manipulation of the computer input device to move the cursor in a first direction on the display device;

generating a second set of electrical signals corresponding to user manipulation of the computer input device to move the cursor in a second direction on the display device orthogonal to said first direction on the display device; and

generating a third set of electrical signals corresponding to user manipulation of the computer input device in a manner independent of user manipulation associated with said first and second sets of electrical signals with said additional electrical power providing electrical power when coupled to the second interface type.