Computer peripheral device network with peripheral address resetting capabilities

• US 5,317,693 A
• Filed: 04/04/1991
• Issued: 05/31/1994
• Est. Priority Date: 04/04/1991
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Digital Equipment Corporation (HP Inc.)
• Inventors: Sichel, Peter A., Cuenod, Jean-Christophe E.
• Primary Examiner(s): Bowler, Alyssa H.
• Assistant Examiner(s): SHAH, ALPESH
• Application Number:
  US07/680,313
• Time in Patent Office: 1,153 Days
• Field of Search: 395/800, 395/325, 395/275, 395/200, 395/575, 370/85.1, 370/85.4, 370/85.8, 370/91-95.2, 370/92, 370/94.1, 371/11.1, 371/11.2, 340/825.06, 340/825.07, 340/825.08
• US Class Current: 710/9
• CPC Class Codes: G06F 12/0661 and decentralised selection
• CPC Class Codes: G06F 12/0684 with feedback, e.g. presence or absence of unit detected by addressing, overflow detection
• CPC Class Codes: G06F 15/177 Initialisation or configuration control processor initialisation G06F9/4405
• CPC Class Codes: G06F 9/4411 Configuring for operating with peripheral devices; Loading of device drivers

Abstract

A desktop communications network connects numerous peripheral devices to a host computer via a single host interface. The host interface and each peripheral device'"'"'s interface has its own CPU, with software for assigning each peripheral device a unique address. The bus interface associated with each peripheral device typically stores a unique identifier string that is used by the host computer to identify each peripheral device connected to the network. Alternately, the host can distinguish identical peripheral devices by the order in which they are first used. As a result, several peripheral devices of the same type can be connected to the network, each being assigned a distinct network address. Peripherals can be connected and disconnected to the desktop bus while the system is running. The software in the host and peripheral bus interfaces automatically reconfigure the assigned bus addresses. Peripherals with sub-devices are accommodated with a communications protocol that allows up to four sub-devices to be connected to each bus interface. Each peripheral device'"'"'s bus interface contains a set of capabilities information that is retrieved by the host'"'"'s interface and is used to determine how the host computer communicates with each peripheral device. For instance, the capabilities information may be used to select a device driver program for use with each peripheral device. In the case of keyboards, the capabilities information may contain a translation table which specifies how the data generated by each keystroke should be interpreted.

Claims

1. Apparatus for coupling a plurality of peripheral devices to a data processing device, comprising:

a communications medium, coupled to said data processing device, for transmitting messages between said data processing device and said plurality of peripheral devices;

a plurality of communications interfaces, each coupled to one of said peripheral devices and to said communications medium, each said communications interface including;

interface memory means for storing;

(A) a currently assigned address value for said communications interface, and

(B) a distinct identification message which identifies said peripheral device coupled to said communications interface; and

reset means for setting said currently assigned address value to a predefined default address value whenever said communications interface is powered up or reset, said reset means including;

(A) means for setting said currently assigned address value stored in its interface memory means to said predefined default address value whenever said communications interface receives a reset message not sent by itself;

(B) means for sending said reset message after said communications interface has been first assigned a unique address value distinct from said predefined default address value, said reset message being sent via said communications medium to said communications interfaces whose currently assigned address value is the same as said unique address value; and

configuration means, in said data processing device, for retrieving said distinct identification messages from all communications interfaces with said currently assigned address value equal to said predefined default address value, and for assigning said unique address value to each communications interface from which said distinct identification message was retrieved, each said unique address value being stored in said interface memory means of the corresponding one of said communications interfaces, said configuration means including;

(A) means for retrieving said distinct identification messages from all communications interfaces which are reset in response to said reset message; and

(B) means for assigning a new unique address value to each such communications interface from which said distinct identification message is retrieved in response to said reset message.

2. The apparatus of claim 1, wherein said predefined default address value is the same in all of said communications interfaces.

3. The apparatus of claim 1, said data processing device including a host controller coupling said data processing device to said communications medium, said host controller including:

a central processing unit;

controller memory means coupled to said central processing unit for storing data;

a transceiver apparatus, coupled to said central processing unit and to said communications medium, for transmitting messages onto said communications medium and for receiving messages transmitted via said communications medium; and

control software, executed by said central processing unit, for controlling communication of data between said peripheral devices and said data processing device, including controlling execution of predefined protocols associated with transmission of data via said communications medium and including said configuration means.

4. The apparatus of claim 1, each said communications interface including:

a transceiver, coupled to said communications medium and said peripheral device, for transmitting messages onto said communications medium and for receiving messages transmitted via said communications medium;

at least one of said peripheral devices including a plurality of sub-devices, and messages transmitted via said communications medium to or from any one of said plurality of sub-devices including destination/source data denoting which sub-device said message is being sent to or from; and

said communications interface for each said peripheral device having a plurality of sub-devices including control means coupled to said transceiver and said sub-devices for generating messages, to be transmitted onto said communications medium by said transceiver, which messages include source data denoting which one of said plurality of sub-devices originated said message, and for conveying received messages with sub-device destination data to the corresponding one of said plurality of sub-devices.

5. The apparatus of claim 4,

said interface memory means of each communications interface further storing:

(C) device capabilities data indicating specific characteristics of said peripheral device coupled to said communications interface;

said configuration means including means for retrieving said device capabilities data from each said communications interface;

wherein said device capabilities data, stored in said interface memory means of communications interfaces that are coupled to a peripheral device having a plurality of sub-devices, includes device capabilities data indicating specific characteristics of one of said plurality of sub-devices.

6. The apparatus of claim 1,

said interface memory means of each communications interface further storing:

(C) device capabilities data indicating specific characteristics of said peripheral device coupled to said communications interface; and

said configuration means including means for retrieving said device capabilities data from each said communications interface and for controlling communication of data between said peripheral devices and said data processing device in accordance therewith.

7. Apparatus for coupling a plurality of peripheral devices to a data processing device, comprising:

a communications medium, coupled to said data processing device, for transmitting messages between said data processing device and said plurality of peripheral devices, each said message denoting a destination address denoting a device to which said message is to be sent, and a source address denoting which device transmitted said message;

a plurality of communications interfaces, each coupled to one of said peripheral devices, each said communications interface including;

interface memory means for storing;

(A) a predefined default address value,

(B) a currently assigned address value for said communications interface, and

(C) a distinct identification message which identifies said peripheral device coupled to said communications interface; and

interface control means, coupled to said interface memory means and said communications medium, for controlling receipt of messages from said communications medium and transmission of messages by said communications interface onto said communications medium, including;

(A) reset means coupled to said communications medium, which, when said data processing device is powered up or reset, transmits an attention message onto said communications medium, said reset means including;

(i) means for setting said currently assigned address value stored in its interface memory means to said predefined default address value whenever said communications interface receives a reset message not sent by itself;

(ii) means for sending said reset message after said communications interface has been first assigned a unique address value distinct from said predefined default address value, said reset message being sent via said communications medium to said communications interfaces whose currently assigned address value is the same as said unique address value;

(B) identification message means, coupled to said communications medium and to said interface memory means, for responding to identification command messages received from said communications medium by transmitting said distinct identification message stored in said interface memory means to said data processing device via said communications medium, said identification message means including means for responding to an address assignment message which includes said currently assigned address value and an identification string matching said distinct identification message stored in said interface memory means by storing said currently assigned address value in said interface memory means as the currently assigned address value for said communications interface;

controller memory means in said data processing device for storing data; and

configuration means, in said data processing device, coupled to said communications medium, said configuration means including;

identification command means for responding to said attention message with a destination address equal to said predefined default address value; and

address assignment means for receiving from said communications medium said distinct identification messages transmitted by said communications interfaces, storing said distinct identification messages in said controller memory means, assigning to each unique one of said distinct identification messages a corresponding unique address value, and transmitting onto said communications medium said address assignment message corresponding to each said unique address value which message denotes said unique address value and said identification string matching said distinct identification message, said address assignment means further including;

(A) means for retrieving said distinct identification messages from all communications interfaces which are reset in response to said reset message; and

(B) means for assigning a new unique address value to each such communications interface from which said distinct identification message is retrieved in response to said reset message.

8. The apparatus of claim 7, wherein said interface memory means in all of said communications interfaces all denote an identical predefined default address value.

9. A method of configuring a network in which peripheral devices are coupled to a host computer by a communications medium that transmits messages therebetween, the steps of the method comprising:

for each said peripheral device, providing an interface coupling said peripheral device to said communications medium;

storing in each interface;

(A) a currently assigned address value for said interface; and

(B) a distinct identification message which identifies said peripheral device coupled to said interface;

whenever any one of said interfaces is powered up or reset, setting said currently assigned address value stored in said interface to a pre-defined default address value;

transmitting to said host computer, via said communications medium, said distinct identification message stored in each one of said interfaces which has said currently assigned address value equal to said predefined default address value; and

assigning a unique address value to each interface which transmitted said distinct identification message, and storing each said unique address value in a corresponding one of said interfaces; and

reassigning a new unique address value to an interface in response to reset messages sent by said interface after said interface has been first assigned said unique address value distinct from said predefined default address value.

10. The method of claim 9,

wherein at least one of said peripheral devices includes a plurality of sub-devices;

transmitting, with each message transmitted via said communications medium by one of said plurality of sub-devices, source data denoting which one of said plurality of sub-devices originated said message;

transmitting, with each message transmitted via said communications medium to one of said plurality of sub-devices, destination data denoting which sub-device said message is being sent to; and

conveying messages with sub-device destination data to the corresponding sub-device.

11. The method of claim 10,

each said interface further storing:

(C) device capabilities data indicating specific characteristics of said peripheral device coupled to said interface;

transmitting said device capabilities data from each said interface to said host computer;

wherein said device capabilities data stored in each said interface that is coupled to a peripheral device having a plurality of sub-devices includes device capabilities data indicating specific characteristics of ones of said plurality of sub-devices.

12. The method of claim 9,

each said interface further storing:

(C) device capabilities data indicating specific characteristics of said peripheral device coupled to said interface;

transmitting said device capabilities data from each said interface to said host computer; and

controlling communication of data between said peripheral devices and said host computer in accordance with said device capabilities data.

13. Apparatus for coupling a plurality of peripheral devices to a data processing device, comprising:

a communications medium, coupled to said data processing device, for transmitting messages between said data processing device and said plurality of peripheral devices;

a plurality of communications interfaces, each coupled to one of said peripheral devices and to said communications medium, each said communications interface including;

interface memory means for storing, including;

(a) a currently assigned address value for said communications interface; and

(b) a distinct identification message which identifies said peripheral device coupled to said communications interface; and

reset means including;

(a) means for setting a predetermined default address value upon said communications interface being powered up or reset by one of said communications interfaces other than itself; and

(b) means for sending a reset message after said communications interface has been assigned a unique address value distinct from said predefined default address value; and

configuration means, in said data processing device, including;

(a) means for retrieving said distinct identification message from all communications interfaces with said currently assigned address value equal to said predefined default address value and assigning a unique address value to each communications interface from which said distinct identification message is retrieved, each said unique address value being stored in said interface memory means of the corresponding one of said communications interfaces; and

(b) means responsive to said reset messages from said communication interfaces for providing new unique address values to those communication interfaces which are reset in response to receipt of said reset message.