EP0458648A2
Expired / Lapsed
EP
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Communication interface for serial transmission of variable length data tokens
Assignee: STMicroelectronics Ltd
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Filing: 1991-05-22
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Granted: —
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Expires: 2011-05-22
Abstract
Abstract A communication interface for interconnecting a computer with at least one other device has a link output circuit and a link input circuit. A link output on one device is connected to a link input on another device by a data line 25 and a parallel strobe line 26. Data is transmitted on the data line 25 in serial bit strings forming a succession of tokens of predetermined lengths. Signal transitions are provided on the parallel strobe line 26 where no signal transition occurs on the data line 25. Each token includes a bit indicating the length of the token and a parity bit providing a check on bits in a preceding token.
Inventors
- 👤 Robert J. Simpson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 23:45
CPC Classifications
H; H04; H04L; H04L1/00; H04L1/004; H04L1/0056; H04L1/0061; H04L1/0063; H04L1/0057; H04L1/0078; H04L1/0083; H04L7/00; H04L7/0016; H04L7/0033; H04L7/0037; H04L7/0008; H04L7/0041; H04L7/02; H04L7/033; H04L7/04; H04L7/048
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
151 words
A communication interface for use in a communication system interconnecting a computer with at least one other device, said interface comprising output circuitry for outputting messages and input circuitry for inputting messages, said output circuitry including control circuitry and encoding circuitry for providing two parallel outputs one in the form of a data signal comprising a serial bit pattern forming at least part of an output message and the other in the form of a strobe signal which, when data is output in the data signal, has signal transitions only at bit boundaries where there is no transition on the parallel data signal, and said input circuitry including decoding circuitry having two inputs, a first input to receive a data signal and a second input to receive a strobe signal, said decoding circuitry being arranged to respond both to data and strobe signals to decode data encoded in said data signal.
Claim 2
Dependent Claim
145 words
A communication interface for use in a communication system interconnecting a computer with at least one other device, said interface comprising output circuitry for outputting messages and input circuity for inputting messages, said output circuitry comprising control circuitry and encoding circuitry for encoding and outputting a succession of tokens each comprising a serial bit string, and a parity bit generator responsive to successive bits in an encoded token and arranged to generate a parity bit after encoding of each token, said parity bit being included in a next token to provide a parity check responsive to the bits in the preceding token, said input circuitry comprising decoding circuitry for inputting and decoding data in each token received and a parity checking circuit to detect a parity bit in each token and compare said parity bit with a bit pattern including bits from the previous token.
Claim 3
Dependent Claim
167 words
A communication interface for use in a communication system interconnecting a computer with at least one other device, said interface comprising output circuitry for outputting messages and input circuitry for inputting messages, said output circuitry comprising control circuitry and encoding circuitry for encoding and outputting a succession of variable bit length tokens each comprising a serial bit string including at least one bit forming a bit length indicator for the token, and a parity bit generator responsive to successive bits after a bit length indicator in a first token up to and including a bit length indicator in a second token and arranged to generate a parity bit for inclusion in each token, said input circuitry comprising decoding circuitry for inputting and decoding data in each token received and a parity checking circuit to detect a parity bit in each token and compare said parity bit with a bit pattern after a bit length indicator in one token up to and including the next bit length indicator.
Claim 4
Dependent Claim
30 words
A communication interface according to claim 1 or claim 2 in which said control circuitry is arranged to output data in said data signal in tokens of predetermined bit length.
Claim 5
Dependent Claim
24 words
A communication interface according to claim 4 in which the control circuitry is operable to output tokens of more than one predetermined bit length.
Claim 6
Dependent Claim
19 words
A communication interface according to claim 5 wherein each token includes a flag to indicate the token bit length.
Claim 7
Dependent Claim
27 words
A communication interface according to claim 1 in which said control circuitry includes a parity bit generator to generate a parity bit for inclusion in each token.
Claim 8
Dependent Claim
43 words
A communication interface according to any one of the preceding claims in which said control circuitry includes a flag bit generator to generate a flay bit for inclusion in each token to identify each token as a data token or a control token.
Claim 9
Dependent Claim
19 words
A communication interface according to claim 8 in which said flag bit provides an indication of the token length.
Claim 10
Dependent Claim
43 words
A communication interface according to claim 8 or claim 9 in which the control circuitry is arranged to provide control tokens and data tokens each having a respective predetermined bit length, each data token having a greater bit length than a control token.
Claim 11
Dependent Claim
45 words
A communication interface according to any one of the preceding claims in which the input circuitry includes delay circuitry connected between each of said two inputs and said decoder and means for varying the delay on one or both of said inputs prior to decoding.
Claim 12
Dependent Claim
58 words
A communication interface according to any one of the preceding claims in which the output circuitry includes flow control means for generating flow control tokens for outputting to a connected communication interface and said input circuitry includes means responsive to input of a flow control token to control operation of the output circuitry in outputting further data signals.
Claim 13
Dependent Claim
36 words
A communication interface according to claim 12 in which said input circuitry includes store means for holding a plurality of data signals and said flow control means is responsive to the contents of said register means.
Claim 14
Dependent Claim
35 words
A communication interface according to claim 8 or claim 9, or claim 10 in which said encoding circuitry is arranged to provide said parity bit and said flag bit at the start of each token.
Claim 15
Dependent Claim
84 words
A communication interface according to any one of claims 8, 9, 10 or 14 in which said parity bit generator is coupled to said encoder so as to respond to the number of bits encoded in a first token after a flag bit in said first token and to supply a parity bit in a first location of a second token indicating an aggregate of said number of bits from said first token together with the parity and flag bits of said second token.
Claim 16
Independent Claim
149 words
A method of effecting communication between at least two interconnected devices, at least one of which devices comprises a computer, said method comprising establishing parallel data signal and strobe signal communication paths between two link interfaces each connected to a respective one of said devices, encoding a serial bit pattern to form a data signal as at least part of an output message and outputting said data signal on the data signal path from one link interface and outputting on the strobe signal path from the said one link interface a strobe signal which, when data is output in the data signal, has signal transitions only at bit boundaries where there is no transition on the parallel data signal, inputting said data and strobe signals in parallel at the other link interface and responding to both said data and strobe signals to decode data encoded in the data signal.
Claim 17
Independent Claim
136 words
A method of effecting communication betweeen at least two interconnected devices, at least one of which devices comprises a computer, said method comprising establishing unidirectional communication paths between two link interfaces each connected to a respective one of said devices, encoding a succession of tokens each comprising a serial bit string, generating a parity bit in response to successive bits of a first token, including said parity bit in a second token following said first token to provide a check on the number of bits in the first token, transmitting said first and second tokens serially from one said link interface to the other link interface, decoding said tokens at said other link interface, detecting said parity bit in the second token and comparing said parity bit with the decoded bit pattern of said first token.
Claim 18
Independent Claim
158 words
A method of effecting communication between at least two interconnected devices, at least one of which devices comprises a computer, said method comprising establishing unidirectional communication paths between two link interfaces each connected to a respective one of said devices, encoding a succession of variable length tokens each comprising a serial bit string including a bit length indicator for the token, generating a parity bit in response to successive bits of a first token following a bit length indicator for the first token up to and including a bit length indicator for a next token, including said parity bit in a token to provide a check on bits in the first token and the bit length indicator of the said next token, transmitting said tokens serially from one said link interface to the other link interface, decoding said tokens at said other link interface, detecting said parity bit and comparing said parity bit with the decoded bit pattern.
Claim 19
Dependent Claim
17 words
A method according to claim 18 in the said parity bit is located in said next token.
Claim 20
Dependent Claim
28 words
A method according to claim 19 in which each said parity bit forms a first bit in a token and said bit length indicator forms a second bit.
Claim 21
Independent Claim
54 words
A method according to any one of claims 16 to 20 further comprising establishing four unidirectional communication paths between each pair of link interfaces, said four paths comprising a first parallel pair of data and signal paths in one direction and a second parallel pair of data and signal paths in the opposite direction.
Claim 22
Independent Claim
25 words
A method according to any one of claims 16 to 21 wherein data is output by a link interface in tokens of predetermined bit length.
Claim 23
Dependent Claim
23 words
A method according to claim 22 wherein data is output by a link interface in tokens of more than one predetermined bit length.
Claim 24
Independent Claim
34 words
A method according to any one of claims 16 to 23 further including generating a flag bit for inclusion in each token to identify the token as a data token or a control token.
Claim 25
Dependent Claim
25 words
A method according to claim 24 wherein said parity bit and flag bit are located at first and second bit positions respectively in each token.
Claim 26
Dependent Claim
47 words
A method according to claim 22 or claim 25 further comprising forming two successive control tokens to form a compound token, the first of said control tokens having a bit pattern indicating that a further token is required to determine the control indicated by the compound token.
Claim 27
Independent Claim
52 words
A method according to any one of claims 16 to 26 wherein messages are transmitted between connected link interfaces in variable length packets, each packet comprising a multiple number of tokens, each token being of a predetermined bit length and providing an end of packet token at the end of each packet.
Claim 28
Dependent Claim
24 words
A method according to claim 27 further comprising including an end of message token at the end of a last packet in a message.
Claim 29
Independent Claim
55 words
A method according to claims 16 to 28 including providing an alignment token to cause simultaneous transitions in said data and strobe paths when no data is transmitted on the data path and using said simultaneous transitions to effect alignment of the signals on the data and strobe paths when input by a link interface.
Claim 30
Independent Claim
62 words
A method according to any one of claims 16 to 29 including forming flow control tokens for outputting by a link interface, outputting data from a first interface to a second interface, outputting a flow control token from said second interface to said first interface to indicate to the first interface that further data tokens may be output to the second interface.
Claim 31
Dependent Claim
64 words
A method according to claim 29 further comprising maintaining a count which is adjusted by output of tokens by an outputting link interface, inhibiting further output of data tokens from said link interface when the count reaches a predetermined number and adjusting said count in response to input of a flow control token from a connected interface to permit output of further data tokens.
Claim 32
Independent Claim
36 words
A method according to any one of claims 16 to 31 wherein each link interface is arranged to output data tokens of a predetermined bit length longer than a second predetermined bit length for control tokens.
Claim 33
Independent Claim
50 words
A method according to any one of claims 16 to 32 wherein each link interface is arranged to output control tokens of two types, a first type for controlling operation of a connected link interface and a second type for use by said device connected to the second link interface.
Claim 34
Dependent Claim
27 words
A method according to claim 33 wherein each link interface is arranged in its input circuitry to store data tokens and control tokens of said second type.
Claim 35
Dependent Claim
39 words
A method according to claim 34 including transferring data tokens and control tokens of said second type from a store in the link interface to a said device connected to the link interface by use of a synchronised handshake.
Claim 36
Independent Claim
52 words
A method according to any one of claims 16 to 35 wherein a link interface is arranged to output a packet which includes in one or more data tokens an address of a communication channel to be used in a said device connected to a link interface arranged to receive said packet.
Claim 37
Independent Claim
35 words
A method according to any one of claims 16 to 36 comprising effecting bidirectional communication between a plurality of devices included in a network having a plurality of microcomputers and at least one routing switch.
References Cited (Backward Citations)
No citation records indexed.
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