Electrical computers and digital data processing systems: input/ – Input/output data processing – Peripheral configuration
Reexamination Certificate
2001-03-08
2004-05-25
Rinehart, Mark H. (Department: 2181)
Electrical computers and digital data processing systems: input/
Input/output data processing
Peripheral configuration
C710S104000, C710S302000, C713S001000
Reexamination Certificate
active
06742055
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a peripheral interface for a personal computer (PC), and more specifically, pertains to a method whereby a plug-and-play function, a feature of the USB (the Universal Serial Bus), is effected without requiring the intervention of an operator.
BACKGROUND OF THE INVENTION
For an extended period of time, serial ports, represented by the standard interface RS-232C, and parallel ports, represented by the Centronics interface, have been the primary peripheral interfaces employed for personal computers (PCs). However, the maximum transmission speeds available with these ports are limited and are lower than those provided by other interfaces. In addition, each of these ports can accommodate only one device, so that if an additional peripheral device is to be connected to a PC, the number of available ports must be increased by one. Furthermore, individual ports are required for display devices, keyboards and mice, so that at present the rear faces of PCs are remarkably busy, and a variety of different ports are displayed for which the required connectors differ in accordance with the apparatuses for which they are to be used. Appropriate cables must therefore be procured and correctly matched when port connections are made, thereby increasing and complicating the labor imposed on operators (users).
To resolve these problems, the USB (Universal Serial Bus) has drawn special attention. The USB standardizes the interfaces and permits the connection to one port of a plurality of peripheral devices. The conventional serial and parallel interfaces basically provide one-to-one connections, and when a plurality of devices, such as a modem and a terminal adaptor (TA), are to be connected, a cable must be re-connected thereto each time, or a switching device is required. However, with USB, a maximum 16 independent functions can be defined for one peripheral device, and using hubs, a maximum 127 peripheral devices can be connected, as a tree. Further, the USB transmission speed is 12 Mbps at the maximum, which is about 100 times that of the RS-232C, the current main serial interface. In addition, USB includes a hot plug function that permits the removal and insertion of cables while the power to peripheral devices is on, and a plug-and-play (Plug & Play) function whereby a PC can automatically identify a peripheral device when it is connected to the PC. In addition to these advantageous features, USB is functionally superior, and as a result, has rapidly drawn attention as the standard peripheral interface that will most probably be used for the next-generation machines.
USB can provide an effective base for a system in which multiple peripheral terminal devices are connected together, and is especially suitable, for example, for a POS (Point Of Sales) system (point of sales information management system) in which multiple peripheral devices, such as a scanners for reading bar codes of product labels, handy terminals, electronic cash registers and touch panels, are connected to a computer called a store controller to which all information is transmitted. While the operation of a conventional POS system entails the use of a dedicated POS interface and software, there is a growing demand for a process by which conventional software, such as Windows, can be utilized to operate a POS system. Further, since in a store wherein mainly a POS system is employed, the connection and disconnection of peripheral devices is probably a frequent occurrence, and the plug-and-play and the hot plug functions of USB will effectively permit anyone to easily extend the system.
As is described above, a USB interface is so designed that it has a maximum of 16 functions (end points) for in and out transactions. However, conventionally, the majority of the USB controller chips sold by individual companies support only three to five end points, and are more distributed than are those that support more end points. A USB controller chip supports a USB interface that is combined with a controller LSI on a USB incompatible peripheral device; however, in order to include multiple functions, as does a POS terminal, the number of end points provided for one USB controller chip is insufficient. Therefore, a plurality of controllers are required, and accordingly, additional peripheral circuits, such as hubs, must be provided, a process that greatly increases manufacturing costs.
Furthermore, the individual functions that are available are normally optional, and since not all functions are employed at the same time, the increase in manufacturing costs involved in supporting optional, additional functions frequently presents an especially large problem for those stores wherein POS terminals are employed. On the other hand, there is a strong demand that the plug-and-play function, a major USB feature, be supported as a connection function, even though it is optional.
SUMMARY OF THE INVENTION
To resolve the above technical shortcomings, it is one object of the present invention to considerably reduce the hardware costs for a system in which the use of USB is supported by the employment of a USB controller chip.
It is another object of the present invention to dynamically reconstruct (re-enumerate) end points that are not used at the same time when the number of end points supported by a USB controller chip is insufficient, and to effectively employ multiple functions.
To achieve the above objects, according to one aspect of the invention, a data transmission system comprises: a controller connected to a bus; and a plurality of functions connected to the controller, wherein the controller selects a predetermined number of functions from among the plurality of functions, and assigns the predetermined number of functions to a plurality of corresponding end points, and wherein, thereafter, the controller selects, from among the plurality of functions connected to the controller, a plurality of different functions, whose constitution is different from the functions that are assigned as the end points to reconstruct end points to provide a configuration that is compatible with the bus.
The bus is compatible with a plug-and-play function, and multiple functions can be connected as end points that are compatible with the bus. This configuration is preferable because the plug-and-play function, which is the feature of the bus, can be provided by software, without the intervention of an operator being required. Further, the bus will match or conform to the USB (Universal Serial Bus) standard.
In addition, when functions that differ from those that are assigned as the end points are requested, those end points that are compatible with the bus can be reconstructed. Such a configuration is superior because necessary functions can be assigned as end points compatible with the subject bus, without having to increase the number of controllers.
The term “end points” is used to indicate functions that are identified, for example, as USB interface terminal functions by a host. The term “thereafter” corresponds to a case wherein, after a system is powered on, a request for the connection of another function is transmitted to a host, or when an operator is manipulating another function.
According to another aspect of the invention, a data transmission system comprises: a host; a controller connected to the host via a plug-and-play compatible bus; and a plurality of functions, provided by the connected controller, that exceed in number the maximum end points that the controller can support, wherein the controller selects a predetermined number of functions from among the plurality of functions and enumerates, as end points, the functions that match in number the maximum end points, and wherein, thereafter, the controller replaces with a different function one of the functions that constitute the end points, and re-enumerates the end points.
When the controller is activated, the controller selects from among the plurality of functions a predetermined number, and assigns the selected functions to end p
Cleary Thomas J.
Gonzalez Floyd A.
International Business Machines - Corporation
Rinehart Mark H.
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