Electrical computers and digital processing systems: multicomput – Computer-to-computer protocol implementing – Computer-to-computer data transfer regulating
Reexamination Certificate
1998-12-22
2001-10-23
Sheikh, Ayaz (Department: 2155)
Electrical computers and digital processing systems: multicomput
Computer-to-computer protocol implementing
Computer-to-computer data transfer regulating
C709S245000, C709S247000, C709S250000, C710S120000, C710S120000, C710S120000, C326S030000, C326S021000, C326S086000
Reexamination Certificate
active
06308215
ABSTRACT:
BACKGROUND
Computer systems typically involve a host computer connected by cable to a peripheral unit (or “function”) such as a keyboard, mouse, printer, modem, joystick, scanner, video camera, game pad, virtual reality devices, data gloves, mechanical devices, or the like. A connecting system of ports and a cable, termed a “bus”, is generally one of two types, either parallel or serial. A parallel bus, usually used for printers, transmits a combination of bits (generally a byte) simultaneously over several wires in a cable. A serial bus transmits the bits in series. However, even a standard serial bus has up to nine wires for auxiliary functions such as request-to-send, data-carrier-detect and other “handshake” signals. Also, different peripherals utilize different port and cable configurations so that interchangability is limited, and a host computer usually contains several different types of ports with connectors for the different peripherals. Moreover, it is difficult to assemble a series of peripherals such as with a mouse connected to a keyboard.
Recently a group of industry leaders developed standards for an advanced system called “Universal Serial Bus”, or “USB”, intended for all types of computer units including peripherals. Only one pair of twisted wires is required in the cable for data transmission, although another pair provides power from a host to the peripheral units. To implement signal transmission and sufficient auxiliary information, both signal wires transmit pulses in parallel with a specified protocol or relativity of signals. During idle condition (no sending of data), one or the other is at a steady voltage with the other at zero, to indicate which of two transmission speeds are in effect. An end of a packet of data or other information (handshake, etc.) is signaled by both wires being at zero voltage before returning to idle. The host arbitrates between peripherals and the host so that while one unit is transmitting the other is in a receive mode.
USB specifications are available from the USB Implementers Forum via internet http://www.usb.org. These allow for up to 127 devices, two speeds and a maximum of 5 meters per cable segment. A computer system can have one or more “starred” hubs for multiple connections of computer units. The length limitation is related to the specifications on time delay, impedance and other electronic aspects that effect allowable noise levels. However, there is a need for longer cables, for example for a host computer controlling other computer units such as video cameras, security devices or building functions, or for connecting two personal computers at a distance.
Accordingly, an object of the invention is to provide an apparatus for extending cable length between computer units that incorporate Universal Serial Bus technology. Another object is to provide such apparatus at a modest cost.
SUMMARY
The foregoing and other objects are achieved by an apparatus for extending USB linkage between a first computer unit and a second computer unit, the units respectively having a first USB port and a second USB port for the linkage. The apparatus includes a first extender port having means for connecting with the first USB port to pass USB signals therebetween, a second extender port having means for connecting with the second USB port to pass USB signals therebetween, a first extender cable connected to carry first extender signals from the first extender port to the second extender port, and a second extender cable connected to carry second extender signals from the second extender port to the first extender port. The first extender port is receptive of first incoming USB signals from the first USB port to effect the first extender signals as representative of the first USB signals, and the second extender port is receptive of the first extender signals to effect first outgoing USB signals to the second USB port. The first outgoing USB signals are representative of the first extender signals, such that the first outgoing USB signals are substantially identical to the first incoming USB signals. Similarly, the second extender port is receptive of second incoming USB signals from the second USB port to effect the second extender signals as representative of the second USB signals, and the first extender port is receptive of the second extender signals to effect second outgoing USB signals to the first USB port. The second outgoing USB signals are representative of the second extender signals, such that the second outgoing USB signals are substantially identical to the second incoming USB signals.
In a preferred aspect, each extender port is formed of an interface circuit with the corresponding USB connections, a driver circuit connected to one extender cable so as to transmit outgoing extender signals, and a receiver circuit connected to the other extender cable so as to receive incoming extender signals. A controller is operatively connected between the interface circuit, the receiver circuit and the driver circuit to selectively effect the outgoing USB signals or the outgoing extender signals. Advantageously each controller is a programmable or ASIC logic device, and each interface circuit includes a USB transceiver.
In further aspects, each receiver circuit effects receiver signals representative of the extender signals incoming to the receiver circuit, and the interface circuit is receptive of the receiver signals to selectively effect outgoing USB signals representative of the receiver signals. The controller has means receptive of the receiver signals to effect an enabling signal that signifies enablement while the incoming extender signals contain a packet sequence, and otherwise signifies disablement. The interface circuit has means receptive of the enabling signal for enabling transmission of the outgoing USB signals only during enablement, so that the outgoing USB signals are transmitted only while the incoming extender signals contain the packet sequence. For the incoming USB signals, the interface signals comprise data signals and speed signals representative of selected speed. The controller is receptive of the data signals, the speed signals and the enabling signal (previously effected by the controller) to effect the outgoing extender signals only during disablement of outgoing USB signals.
In a typical USB interface circuit, the speed signals are also intermittently representative of non-speed data; in such case it is advantageous for at least one controller to include further means for converting the speed signals into a speed indicator signal representative only of selected speed. The indicator signal is representative of the speed signals to effect the enabling signal with the receiver signals.
The first and second extender cables are combined conveniently into a single extender cable containing several other electrical lines. For one such line, only one controller effects a speed indicator signal, and a signal line is connected to transmit the speed indicator signal to the other controller. For another such line, the first extender port further includes a first power supply for powering circuit components and signals of the first extender port. This power supply has a first input connector receptive of an external power source such as 24 volts DC, and has a first output connector connected to the first input connector. The second extender port further includes a second power supply for powering circuit components and signals of the second extender port. The second power supply has a second input connector for power input. The combined cable includes a power line connecting the first output connector and the second input connector to power the second power supply from the same external power source.
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patent: 5655138 (1997-08-01), Kikinis
patent: 5675813 (1997-10-01), Holmdahl
patent: 5767844 (1998-06-01), Stoye
patent: 5781028 (1998-07-01), Decuir
patent: 6105097 (2000-08-01), Larky et al.
patent: 6131125 (2000-11-01), Rostoker
patent: 6151653 (2000-11-01), Lin et al.
patent: 6178514 (2001-01-01),
Ingham Michael O.
Kolbet Robert J.
Duong Oanli
Ingham H. S.
Sheikh Ayaz
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