Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/14—Two-way operation using the same type of signal, i.e. duplex
  • H04L5/1423—Two-way operation using the same type of signal, i.e. duplex for simultaneous baseband signals

Definitions

• the invention relates to methods and apparatus for bidirectional data transmission between at least two communication participants according to the preambles of the independent claims.
• the data transmission takes place between a peripheral device and a
• Control unit in an airbag system is a control unit in an airbag system.
• DE 196 09 290 AI shows an airbag system for protecting vehicle occupants.
• a plurality of sensor modules are provided therein, which are connected to a remote control unit via line pairs.
• the control unit controls a restraint device for vehicle occupants, such as in particular an airbag.
• the output signals from the sensor modules are in the form of mutually juxtaposed changes in the current flow on both
• Cables ie in the form of analog push-pull signals or in the form of a pulse train to the control unit.
• the data are realized by changes in the voltage that are juxtaposed. Communication is delayed, that is, on the basis of a request signal in the form of changes in the voltage which are adjacent to one another, the control unit signals the start of transmission to the sensor modules and then the data are transmitted in the opposite direction, that is to say from the sensor modules to the control unit, the data are transmitted in the form of mutually adjacent changes in the current flow on the line pair.
• the unpublished German application 198 13 965.9 shows a method for transmitting digital data with a clock transfer generator that is controllable in its clock frequency.
• the data transmission from a peripheral device to a control device by means of signal edges of the current flow is described in a special form.
• the coding of the binary states is thus defined by a rising or falling signal edge, which must be detected in a certain time window.
• the data transfer clock generator frequency can be synchronized by additionally using Manchester coding.
• the time shift that occurs between the data pulses and the synchronization times of the edge changes is determined by a time-shifted sampling of the logic level
• the invention is based on a method and one
• the invention further develops the content of the unpublished German application 198 13 965.9 in such a way that bidirectional and simultaneous data transmission is possible in both communication directions.
• the content of the German application 198 13 965.9 is thus also the content of the illustrated invention.
• Communication subscriber in particular a peripheral device to the second communication subscriber, in particular a control device, is realized by signal edges of the current flow, while the change in the voltage level
• Communication from the control device to the periphery wherein the transmission from the communication participant 1 to the communication participant 2, that is, from the periphery to the control device according to the above not previously published German application, is a fast digital Data transmission from the periphery to a control device with its characteristic advantages achieved and additionally the ability to bidirectionality of the interface achieved by sensing the change in the potential on the connecting line.
• the Manchester code in particular the Manchester II code, can expediently be adopted in both communication directions for coding the digital information.
• the data rates can be increased by self-synchronizing coding of the digital data for communication in both directions.
• the data transmission from communication participant 2, ie the control device to communication participant 1, ie the periphery can be implemented by any coding, for example in addition to the Manchester or Manchester II code, for example also by the Hamming code or the Abramson code. Code, etc.
• the interface according to the invention can make it possible to operate the interface according to the ISO 9141 standard by simply varying the components used (fitting variant).
• the synchronization takes place in the middle of a pulse, in particular a data pulse, and is therefore advantageously and always possible due to the edge change occurring there.
• the time period between two synchronization times in the middle of the pulse is expediently used in Manchester coding as the time range representing the clock frequency.
• the clock frequency is detected by means of the known counting of the oscillator clocks and the Data transfer generator takes the current clock frequency in the middle of the pulse, however, the data transfer generator detects the pulse level at different times, which means that it adapts to them advantageously.
• both pulse halves are expediently scanned at least once before and after the time of synchronization in the middle of the pulse.
• the scanning is advantageously carried out by means of multiple scanning within a scanning window.
• FIG. 1 A possible basic structure of a device for data transmission according to the invention is described in FIG.
• Figure 2 shows in principle the data transmission from the communication participant 2, that is, the control unit to
• Communication subscriber 1 i.e. the peripheral device.
• the transmission is shown on the one hand with an intermediate level and on the other hand with a real low level by switching on and off.
• the transmission of the data from communication subscriber 1 to communication subscriber 2 is described in the not previously published German application 198 13 965.9 and is based on the content.
• Figure 1 shows a basic structure of the interface.
• 101 is a switching logic or semiconductor intelligence, in particular in the form of a
• At least one peripheral device 100 is connected to the switching logic 101.
• the switching logic 101 with the at least one peripheral device 100 represents, for example, the communication subscriber Kl.
• a control device can thus also be provided as the communication subscriber 1.
• Line 114 is the output line from the switching logic 101.
• Line 115 is the input line which leads to the switching logic 101.
• the switching logic 101 is connected via line 114 to a consumer 102, which in turn is connected to a switching means 105, in particular a transistor.
• the switching means 105 is connected on the one hand to ground and on the other hand to another consumer 104.
• Consumer 104 is connected to a further consumer 106, which in turn is connected to ground. With consumer 104 and
• Consumer 106 is connected to another consumer 109. On the opposite side, this is connected to a potential on pin 108, in particular the supply voltage UBAT.
• An energy store in particular a capacitor 110, which is also connected to ground, is connected to the common potential point of the three consumers 104, 106 and 109.
• the common potential point or the common line section of the consumers 104, 106 and 109 and of the energy store 110 leads into a comparator 103.
• a pin 107 is also guided into the comparator 103 which has a potential VC.
• the comparator 103 is connected on the output side to the switching logic 101 via line 115.
• the components and connecting lines just described are parts of the periphery P according to the invention. This periphery P is via the
• Transmission line T connected to the control unit area S.
• the transmission line T begins in the peripheral port Pp which is connected to the comparator 103 via the common line section described above.
• the connection of the control unit area S thus the connection to the transmission line T, that is to say the control unit port, is denoted by Ps.
• the transmission line T is connected via port Ps via line 118 to the communication subscriber K2 and at the same time to a consumer 111.
• Consumer 111 is also connected to communication subscriber K2 via a line 117.
• an energy store in particular a capacitance 112, which is simultaneously connected to ground.
• Communication subscriber K2 contains an evaluation circuit or evaluation logic 113 or corresponding semiconductor intelligence in the form of, for example, a microcontroller and, with 116, an actual microcontroller of a control device.
• the evaluation circuit 113 and the microcontroller 116 are accommodated in an integrated module. 116 can thus only be a microcontroller, but also a complete control unit, in which case logic 113 can then be swapped out.
• the interface according to the invention requires at least one electrical connection T between the periphery P and the control unit area S, which transmits the data information in both directions.
• the reference potential in particular ground, can be the reference potential of the control device through a further electrical connection (not shown here) be or refer to the reference potential at another peripheral location.
• the switching logic 101 takes over the edge control according to Manchester II coding for output line 114 as well as the evaluation and further processing of the serial voltage levels, for example in Manchester II coding, for input line 115.
• Output line 114 thus represents the signal path of all data transmission to the control device, while input line 115 connects the communication to the periphery P with the switching logic 101.
• Switching means 105 is described below as a bipolar transistor. However, the switching means 105 can also have a different configuration, for example a unipolar transistor or a further switching logic.
• the base of transistor 105 is controlled via load 102 as a voltage divider. If transistor 105 switches, an increased current flow is made possible via transmission line T, the potential of transmission line T being maintained due to load 104. A residual current can also be ensured via transmission line T via consumers 106, even when transistor 105 is closed.
• Energy storage 110 may be one or more
• Protection capacities are realized and contributes to smoothing the edges of the data transmission signal and reducing the radiation of the transmission line T.
• 103 shows a comparator circuit which serves to compare the potential of the transmission line T with the potential VC on pin 107 and thus transfers the coded digital message from the control unit area S to the switching logic 101 via line 115.
• a supply voltage, in particular UBAT, or the associated potential of pin 108 is coupled in via consumer 109.
• the logic 113 can be implemented, for example, by an ASIC.
• the typical potential on transmission line T is regulated by logic element 113.
• Logic element 113 can thus encode, in particular according to
• the energy store 112 is a protective capacitance for protection against voltage or interference coupling into the logic element 113.
• Logic element 113 has the ability to reduce the potential of the transmission line T to a residual potential (e.g.> 100 mv) VTl or an intermediate potential VTlz and to raise it again to the typical potential on transmission line T by means of a corresponding control by the microcontroller 116.
• This potential change on transmission line T can be applied to the switching logic 101 on the peripheral side by means of the comparator circuit 103 and the comparison of the potential of the transmission line T with the potential via pin 107, VC via line 115.
• the output of the comparator circuit 103 thus transmits the coded, in particular Manchester II-coded, digital message of the switching logic 101
• control device side S can on the one hand be accommodated completely in the control device, and the control device can also comprise only the logic module 113 and the microcontroller 116 in addition to other known components. Then the circuit of elements 111, 112, 117 and 118 would be on the control unit side, but upstream of the actual control unit. Likewise, logic element 113, in particular as ASIC, could be upstream of the control unit as communication partner K2. Due to this possible outsourcing, which is also possible on the peripheral side P, one of
• Peripheral device 100 and control device or microcontroller 116 independent transmission path that can be connected to this can be implemented in one device.
• the implementation of the interface shown in FIG. 1 corresponds to the configuration variant mentioned according to ISO standard 9141.
• An intermediate potential is achieved by the connection 108 and the load 109 coupling in its potential. This potential is therefore between the residual potential when the switching means 105 is switched off and the potential when the switching means 105 is switched on.
• an interface according to ISO standard 9141 is achieved, that is to say operation according to ISO 9141 of the interface shown.
• connection 108 and consumer 109 are dimensioned differently accordingly.
• a charge pump ie an energy supply, must be available on both sides for simultaneous transmission.
• FIG. 2 shows implementation options for the communication direction of the control device side S to the periphery P. Two options are presented for realizing simultaneous transmission in both communication directions.
• the first is an implementation with intermediate potential VTlz, shown in signal flow SP1 with one-sided
• the second possibility is to provide own power supplies for the peripheral side P and the control device side S if these do not draw their energy via the electrical connection T of the interface. Then it only has to be ensured that the interface can be switched on and off repeatedly.
• Option 1 also shows an intermediate level VTlz, an intermediate low level, so to speak.
• the switch-on process creates a potential VTh at tl.
• the actual transmission of the data is then represented at time t2 by at least one start bit from t2 to t3.
• the Manchester II coding is also selected here, after which synchronization takes place in the middle of the pulse, which allows the advantages of the Manchester II coding for both communication directions to use.
• further data bits are transmitted at times t4 and t5. For example, a total of 8 data bits, i.e. 1 byte, are transmitted per transmission frame.
• a parity bit is then transmitted for data checking and finally a stop bit for frame limitation at time t7.
• the digital messages can be encoded in accordance with the Manchester II encoding or in accordance with further, in particular cyclic, codes such as Hamming or Abramson.
• the low level for SP 1 corresponds here to an intermediate level which is below the high level VTh.
• This level VTlz guarantees at the same time a sufficient current flow for the opposite direction, not shown, from the communication subscriber 1 to the communication subscriber 2
• the signal is changed from the low level VTl to the high level VTh when switching on at tll.
• transmission is started with at least one start bit.
• a further start bit or the first data bit can be transmitted at time t31.
• Another data bit is transmitted at time t4l.
• the further procedure corresponds to that of SP1 with the difference that the change between the low potential VT1 and the high potential VTh is carried out. Since the current flow associated with the low potential VT1 in the opposite direction from K1 to K2 is not sufficient for data transmission, the use of own energy or power supplies on the peripheral side P and control unit side S is necessary for a simultaneous transmission.
• the interface would be switched off at level low VTl and no communication from peripherals to control unit, i.e. from K1 to K2, would be possible via changes in current flow.
• the communication directions would then have to be loaded with a time delay, ie the communication would take place with a time delay, as in the prior art.
• the methods and devices shown allow the high demands, in particular in the automotive sector, to be taken into account in terms of data security, data rate and system solution costs. This also enables the possibility of detecting and compensating for data failures during data transmission, while at the same time achieving greater robustness against EMC influences.
• the methods and the devices can be used independently of a special application, specifically wherever data transmission between at least two communication participants is desired.
• they also offer drive control, chassis and brake control as well as transmission control processes, etc.
• other electronics such as door locks or window regulators with a control unit is being considered.

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• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Dc Digital Transmission (AREA)
• Small-Scale Networks (AREA)
• Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
• Bidirectional Digital Transmission (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 1999
  • 1999-09-29 DE DE1999146776 patent/DE19946776A1/de not_active Ceased
• 2000
  • 2000-07-28 EP EP00954377A patent/EP1221220A2/de not_active Withdrawn
  • 2000-07-28 JP JP2001527501A patent/JP2003527781A/ja active Pending
  • 2000-07-28 AU AU66854/00A patent/AU6685400A/en not_active Abandoned
  • 2000-07-28 WO PCT/DE2000/002478 patent/WO2001024441A2/de not_active Application Discontinuation

Non-Patent Citations (2)

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