Wireless serial port transceiver

• US 6,163,538 A
• Filed: 10/09/1997
• Issued: 12/19/2000
• Est. Priority Date: 10/09/1997
• Status: Expired due to Fees

• Current Assignee: Paxar Americas Incorporated (Avery Dennison Corporation)
• Original Assignee: Monarch Marking Systems, Inc. (Avery Dennison Corporation)
• Inventors: Brown, John P., Morrison, Donald A., Tincher, Terry L.
• Primary Examiner(s): Pham, Chi H.
• Assistant Examiner(s): Pham, Brenda H.
• Application Number:
  US08/948,271
• Time in Patent Office: 1,167 Days
• Field of Search: 370/389, 370/349, 370/242, 370/244, 370/311, 370/312, 370/338, 370/401, 370/402, 370/475, 370/336, 370/462, 309/237, 710/1, 235/375, 235/472.01, 235/472.02, 455/517
• US Class Current: 370/389
• CPC Class Codes: G06K 7/10851 Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device basic electronic circuitry H03
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 52/0241 where no transmission is received, e.g. out of range of the transmitter
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A pair of compact, energy-efficient, intelligent, wireless transceiver units are designed to replace the cable that interconnects a portable bar-code scanner, keyboard, and display or other host to a portable bar-code printer or the like. When reset, the units exchange linkage packets and thereby exchange addresses. Thereafter, the two units communicate in an error-free fashion with each other, even in the presence of noise and interference, by exchanging addressed packets containing error detection information. Alternate transmission frequencies are selected when transmissions cannot be received at one frequency. The host unit may maintain independent linkages with multiple printers or the like, with a switch on the host unit selecting the desired printer. Power usage is minimized by shutting down transmitters, receivers, serial port drivers, and microprocessors whenever possible, and for extended periods when data is not being transmitted.

Claims

1. An apparatus for transferring data between a source of information and a sink for information by a wireless linkage comprising:

a first transceiver unit connecting to said source of information and having an address;

a second transceiver unit connecting to said sink for information and having an address;

a control on each of said first and second units for placing them into a first linkage mode;

a handshake protocol within each of said first and second units, placed into operation when the units are in said first linkage mode, which causes them to continuously attempt to handshake with another transceiver unit and exchange addresses by one broadcasting its address and by the other responding with its own address;

said first and second units, following the successful execution of said address exchange handshake between them, placing themselves into a data communications mode where each communicates exclusively with the other and where said first and second units remain in said data communications mode indefinitely; and

said units thereafter wirelessly transferring data in the form of packetized, error correctable, addressed data packets, and also transferring addressed acknowledgments of successful receipt of such data packets, to transfer data in an error-free manner between said source and said sink.

2. An apparatus in accordance with claim 1 wherein:

said units respond to the receipt of erroneous packets by transmitting addressed negative acknowledgement packets in response to which the units re-transmit the erroneously received packets.

3. An apparatus in accordance with claim 2 wherein:

said units switch to a different transmission frequency following the transmission and receipt of an unacceptable number of negative acknowledgement packets.

4. An apparatus in accordance with claim 1 wherein:

at least one of said transceiver units includes a switch actuation of which permits it first to link with and secondly to exchange data with plural second transceiver units each corresponding to a switch setting.

5. A method for establishing a wireless linkage between a source and a sink for information comprising the steps of:

placing the source and the sink into a first linkage mode where each is seeking out a linkage partner;

while both are in the linkage mode, causing the source and sink to continuously attempt to handshake with each other through an exchange of addresses between said source and sink;

having said source and sink, following a successful address exchange handshake, switch into a second data communications mode where each communicates by address exclusively with the other and where said source and said sink then remain in said data communications mode indefinitely; and

while both are in the data communications mode, having the source send addressed, packetized, error detectable data packets to the sink, and having the sink return addressed acknowledgments of successful packet receipt.

6. A method in accordance with claim 5 which further includes the steps of:

having the sink return addressed negative acknowledgements of unsuccessful packet receipts, and

having the sink respond by resending the data packet sent previously.

7. A method in accordance with claim 6 which further includes the step of

having the source and sink switch to a different transmission frequency whenever an excessive number of negative acknowledgements are sent out by the sink in succession.

8. A method in accordance with claim 5 wherein there are plural sinks, and which further includes the step of:

switching the source to any of the sinks first for the linkage handshake end thereafter for data transfer, whereby the source may be selectively and successively linked to any desired one of the sinks.

9. A wireless link designed to replace an industry-standard transmission cable having first and second signal connectors, comprising:

first and second transceiver units having respectively first and second signal connectors;

a control on each unit for placing the unit into a first linkage mode;

a handshake protocol within each unit placed into operation when the unit is in said first linkage mode which enables one of a pair of such units to broadcast its address and which enables the other of the pair of such units to capture the broadcast address and to return its own address;

a control within each unit when in said first linkage mode that senses the successful completion of an exchange of addresses between two such units in linkage mode and that thereafter places the units which exchanged addresses into a second data transmission mode, wherein they can send addressed data packets to each other;

a data exchange protocol within each pair of units, when the units are address-linked in said second data transmission mode, which causes them to receive data from the signal connector, packetize the data, send the packetized, addressed, error detectable packets via radio to the other unit, receive such addressed packetized data, check the data for errors, acknowledge an accurate transmission by sending a return-addressed acknowledgement packet to the other unit, and present the data to the signal connector.

10. A wireless link in accordance with claim 9 wherein said transceiver units include a switch in each position of which switch the transceiver may first link to and later communicate with a different other transceiver unit.

11. A wireless link in accordance with claim 9 wherein at least one of said transceiver units are battery powered and conserve power by powering down its transmitter and receiver and connector when not in use.

12. A wireless link in accordance with claim 9 wherein at least one of said transceiver units draws its power from the terminals of the connector and conserves power by powering down its transmitter and receiver when not in use.

13. A wireless link in accordance with claim 9 wherein the connectors include flow control signals, and wherein said transceivers respond to, and generate, said flow control signals as needed to prevent loss of data.

14. A wireless link in accordance with claim 9 wherein one unit connects to a printer and is able to test the printer and, if the printer is not ready to proceed, is further able to instruct the other unit not to accept incoming information destined for the printer.

15. A pair of identical wireless transceivers designed to be used in pairs as a wireless transmission linkage and designed to conserve power, each comprising:

a power supply;

a transmitter;

a receiver;

a data port;

a programmed microprocessor having facility for data input and output, connecting to said transmitter, receiver, data port, and power supply, and programmed to transfer data between said data port and said transmitter and receiver, packetizing data presented to said transmitter with address and error detection data and unpacketizing and error checking data received from said receiver, discarding erroneous data received from said receiver and requesting its retransmission;

means controlled by said programmed microprocessor for powering down said transmitter when not transmitting, said receiver when not receiving, and said data port when not transferring;

means for causing each unit to initially exchange addresses with another unit and thereafter communicate only with said other unit, thereby forming a linked pair of units; and

means actuated during idle periods, for powering up the receiver in one of a pair of units only periodically, at certain times, and timing means arranging for the other of such a pair of units to commence transmitting data packets only at such times.

16. A pair of transceivers in accordance with claim 15 wherein said port includes incoming and outgoing flow control signals, wherein said units send said flow control signals to the transmitter and receive them from the receiver, and wherein said units power themselves down promptly when said flow control signals indicate that an idle period is commencing.

17. A wireless data switch interconnecting a source of data with multiple sinks of data comprising:

a first unit connecting to said source and arranged to receive information from said source;

for each said sink, a second unit connecting to said sink and arranged to present information to said sink;

each said unit having a transmitter and a receiver and a data port for connecting to said source or sink;

switch means in said first unit for selecting one of several possible sinks of information;

means associated with each said second unit including an address enabling it to broadcast said address when placed into a first linkage state and, later, to receive addressed data packets when placed into a second data transfer state; and

means associated with said first unit, when said switch means is in any given position, for first entering a linkage state continuously seeking and attempting to accept the address one of said second units that is also in said first linkage state and for thereafter, following a successful acceptance of a selected second unit'"'"'s address, whenever said switch means is in that same position, entering a data transfer state wherein source data is sent in addressed packets exclusively to said selected one of said second units for presentation to said associated sink, and thereafter both said first unit (whenever said switch means is in that same position) and said selected one of said second units remain in said data transfer state indefinitely;

whereby the source may be linked by wireless addressed linkage to plural sinks and may thereafter send data to any one of them under control of said switch.

18. A wireless data switch in accordance with claim 17 wherein said sources and sinks of data generate and receive flow control signals from said units, and wherein said units exchange said flow control signals over said wireless network and present them to the opposite source or sink, and wherein during idle periods resulting from either flow control or lack of data said units power down their transmitters, receivers, and connections to said source and sinks, to conserve power.

19. A wireless data switch in accordance with claim 18 wherein, during idle periods caused by either flow control activity or lack of data, said units power down internal transmitters, receivers, and connections to said source and sinks, maintaining only occasional transmissions as needed to maintain linkages.

20. An apparatus for transferring data between a source of information and a sink for information by a wireless linkage comprising:

a first battery powered transceiver unit connecting to said source of information and having an address;

a second battery powered transceiver unit connecting to said sink for information and having an address;

a control on each of said first and second units for placing them into a first linkage mode;

a handshake protocol within each of said first and second units, placed into operation when the units are in said first linkage mode, which causes them to continuously attempt to handshake with another transceiver and exchange addresses by one broadcasting its address and by the other responding with its own address;

said first and second units, following the successful execution of said address exchange handshake between them, placing themselves into a data communications mode where each communicates exclusively with the other and where said first and second units remain in said data communications mode indefinitely;

said units thereafter wirelessly transferring data in the form of packetized, error correctable, addressed data packets, and also transferring addressed acknowledgements of successful receipt of such data packets, to transfer data in an error-free manner between said source and said sink; and

said units conserving power by shutting down transmitter, receiver, and connector components when not conveying or waiting for information.

21. An apparatus in accordance with claim 20 wherein:

said units respond to the receipt of erroneous packets by transmitting addressed negative acknowledgement packets in response to which the units re-transmit the erroneously received packets.

22. An apparatus in accordance with claim 21 wherein:

said units switch to a different transmission frequency following the transmission and receipt of an unacceptable number of negative acknowledgement packets.

23. An apparatus in accordance with claim 20 wherein:

at least one of said transceiver units includes a switch actuation of which permits it first to link with and secondly to exchange data with plural second transceiver units each corresponding to a switch setting.

24. A wireless link designed to replace an industry-standard transmission cable having first and second signal connectors, comprising:

first and second transceiver units having respectively first and second signal connectors, at least one of said transceiver units is being battery powered and conserving power by powering down its transmitter and receiver and connector when not conveying or awaiting information;

a control on each unit for placing the unit into a first linkage mode;

a handshake protocol within each unit placed into operation when the unit is in said first linkage mode which enables one of a pair of such units to broadcast its address and which enables the other of the pair of such units to capture the broadcast address and to return its own address;

a control within each unit when in said first linkage mode that senses the successful completion of an exchange of addresses between two such units in linkage mode and that thereafter places the units which exchanged addresses into a second data transmission mode, wherein they can send addressed data packets to each other;

a data exchange protocol within each pair of units, when the units are address-linked in said second data transmission mode, which causes them to receive data from the signal connector, packetize the data, send the packetized, addressed, error detectable packets via radio to the other unit, receive such addressed packetized data, check the data for errors, acknowledge an accurate transmission by sending a return-addressed acknowledgement packet tot he other unit, and present the data to the signal connector.

25. A wireless link in accordance with claim 24 wherein said transceiver units include a switch in each position of which switch the transceiver may first link to and later communicate with a different other transceiver unit.

26. A wireless link in accordance with claim 24 wherein at least one of said transceiver units draws its power from the terminals of the connector.

27. A wireless link in accordance with claim 24 wherein the connectors include flow control signals, and wherein said transceivers respond to, and generate, said flow control signals as needed to prevent loss of data.

28. A wireless link in accordance with claim 24 wherein one unit connects to a printer and is able to test the printer and, if the printer is not ready to proceed, is further able to instruct the other unit not to accept incoming information destined for the printer.

29. A pair of identical wireless transceivers designed to be used in pairs as a wireless transmission linkage and designed to conserve power, each comprising:

a battery power supply;

a transmitter;

a receiver;

a data port;

a programmed microprocessor having facility for data input and output, connecting to said transmitter, receiver, data port, and battery power supply, and programmed to transfer data between said data port and said transmitter and receiver, packetizing data presented to said transmitter with address and error detection data and unpacketizing and error checking data received from said receiver, discarding erroneous data received from said receiver and requesting its retransmission;

means controlled by said programmed microprocessor for powering down said transmitter when not transmitting, said receiver when not receiving, and said data port when not transferring;

means for causing each unit to initially exchange addresses with another unit and thereafter communicate only with said other unit, thereby forming a linked pair of units; and

means actuated during idle periods, for powering up the receiver in one of a pair of units only periodically, at certain times, and timing means arranging for the other of such a pair of units to commence transmitting data packets only at such times.

30. A pair of transceivers in accordance with claim 29 wherein said port includes incoming and outgoing flow control signals, wherein said units send said flow control signals to the transmitter and receive them from the receiver, and wherein said units power themselves down promptly when said flow control signals indicate that an idle period is commencing.

31. A pair of wireless transceiver units that can interconnect a source of information with a sink for information, said source and said sink generating flow control signals, said units comprising:

within each unit, means for transmitting and receiving at either of two or more frequencies;

within a first unit connected to said source, means for accepting information from said source, packetizing the information with the address of the other unit and error detection information, and transmitting said packets at a first frequency using direct carrier waive modulation by the binary data;

within a second unit interconnected to a sink, means for receiving and error checking said packets at said first frequency, responding with an acknowledgement or negative acknowledgement packet in accordance with the presence or absence of errors, and sending error-free data to said sink;

within said first unit, means for responding to a negative acknowledgement packet by retransmitting the packet most recently sent;

means within both said units for shifting transmission and reception frequencies after an excessive number of successive negative acknowledgement packets have been sent by said second unit; and

wherein said units communicate said flow control signals between the source and sink to achieve overall data flow control.

32. A pair of wireless transceiver units that can interconnect a source of information with a sink for information comprising:

within each unit, means for transmitting and receiving at either of two or more frequencies;

within a first unit connected to said source, means for accepting information from said source, packetizing the information with the address of the other unit and error detection information, and transmitting said packets at a first frequency using direct carrier wave modulation by the binary data;

within a second unit interconnected to a sink, means for receiving and error checking said packets at said first frequency, responding with an acknowledgement or negative acknowledgement packet in accordance with the presence or absence of errors, and sending error-free data to said sink;

within said first unit, means for responding to a negative acknowledgement packet by retransmitting the packet most recently sent;

means within both said units for shifting transmission and reception frequencies after an excessive number of successive negative acknowledgement packets have been sent by said second unit; and

if successive negative acknowledgement packets continue to be sent following a change in frequency, or if neither acknowledgement nor negative acknowledgement packets are received at appropriate times, and error indication is given to signal a failure of communication.

33. A pair of wireless transceiver units that can interconnect a source of information with a sink for information comprising:

within each unit, means for transmitting and receiving at either of two or more frequencies;

within a first unit connected to said source, means for accepting information from said source, packetizing the information with the address of the other unit and error detection information, and transmitting said packets at a first frequency using direct carrier wave modulation by the binary data;

within a second unit interconnected to a sink, means for receiving and error checking said packets at said first frequency, responding with an acknowledgement or negative acknowledgement packet in accordance with the presence or absence of errors, and sending error-free data to said sink;

within said first unit, means for responding to a negative acknowledgement packet by retransmitting the packet most recently send;

means within both said units for shifting transmission and reception frequencies after an excessive number of successive negative acknowledgement packets have been sent by said second unit;

if successive negative acknowledgement packets continue to be sent following a change in frequency, or if neither acknowledgement nor negative acknowledgement packets are received at appropriate times, an error indication is given to signal a failure of communication; and

reset switches which, when actuated on both units at about the same time, cause the two units to re-initiate their efforts to communicate.