Method of generating a clock signal in a module of a data transmission system, and correspondingly equipped data transmission system

• US 6,587,532 B1
• Filed: 09/24/1998
• Issued: 07/01/2003
• Est. Priority Date: 09/24/1997
• Status: Expired due to Fees

• Current Assignee: Continental Automotive GmbH (Continental AG)
• Original Assignee: Siemens AG
• Inventors: Hermann, Stefan
• Primary Examiner(s): Bayard, Emmanuel
• Application Number:
  US09/161,199
• Time in Patent Office: 1,741 Days
• Field of Search: 375/356, 375/358, 375/359, 375/376, 375/373, 375/327, 375/215, 375/219, 332/127, 329/325, 329/307, 329/304, 331/21, 331/25, 331/55, 327/37, 327/2, 327/141, 327/147, 327/144, 455/260, 455/265, 455/73
• US Class Current: 375/376
• CPC Class Codes: B60R 2021/01068 between different sensors and airbag control unit
• CPC Class Codes: B60R 21/01 Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents electrical circuits for transmission of signals between steering wheel and the vehicle itself B60R16/027; for electrically actuating belt retractor locking means B60R22/343
• CPC Class Codes: H03L 7/06 using a reference signal applied to a frequency- or phase-locked loop
• CPC Class Codes: H04L 7/00 Arrangements for synchronising receiver with transmitter synchronisation of generators of electric oscillations or pulses H03L7/00
• CPC Class Codes: H04L 7/033 using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop
• CPC Class Codes: H04L 7/04 Speed or phase control by synchronisation signals H04L7/0075 takes precedence

Abstract

The invention relates to a method for generating the working clock in a module of a data transmission system. The system is particularly suitable for use in a vehicle occupant protection system of a motor vehicle. A control unit of the data transmission system transmits a synchronization clock signal to the module. The module contains a frequency-locked and/or phase-locked loop which receives the synchronization clock signal and which generates the module working clock on the basis of the synchronization clock signal.

Claims

1. A method of generating a working clock in a module of a data transmission system, which comprises:

generating a synchronization clock signal in a control unit of the data transmission system in the form of voltage pulses;

transmitting, with the control unit, the synchronization clock signal to the module of the data transmission system via a bidirectional interface;

receiving the synchronization clock signal with a frequency-locked and/or phase-locked loop in the module;

generating, with the frequency-locked and/or phase-locked loop a working clock on basis of the synchronization clock signal;

controlling an operation of the module with the working clock; and

transmitting data from the module to the control unit in the form of current pulses via the bidirectional interface.

2. The method according to claim 1, wherein the controlling step comprises controlling transmission and reception processes with the working clock.

3. The method according to claim 1, wherein the control unit and the module are components of a vehicle occupant protection system in a motor vehicle.

4. The method according to claim 1, wherein the synchronization clock signal is a low-frequency signal, and wherein the generating step comprises subjecting the clock signal to a frequency multiplication in the frequency-locked and/or phase-locked loop and forming the working clock.

5. A data transmission system, comprising:

a control unit with a synchronization clock signal generator generating a synchronization clock signal;

a module with a frequency-locked and/or phase-locked loop;

a data transmission line connecting said module to said control unit, said data transmission line being a bidirectional interface acting as a voltage interface in a direction from said control unit to said module for transmitting the synchronization clock signal from said control unit to said module, and acting as a current interface in a direction from said module to said control unit for transmitting data from said module to said control unit; and

said frequency-locked and/or phase-locked loop of said module receiving the synchronization clock signal generated by said synchronization clock generator of said control unit, and, based on the synchronization clock signal, generates a working clock controlling an operation of the module, including transmission and reception processes of said module.

6. The data transmission system according to claim 5, wherein said control unit and said module are integral components of a vehicle occupant protection system in a motor vehicle.

7. The data transmission system according to claim 5, wherein said frequency-locked and/or phase-locked loop includes a frequency multiplier for frequency-multiplying a signal formed internally from the synchronization clock signal.

8. The data transmission system according to claim 5, wherein said control unit is operated at a given working clock, and said synchronization clock generator is a voltage source actuated in dependence on the working clock of said control unit.

9. The data transmission system according to claim 5, wherein said module transmits data to said control unit in the form of current pulses, and said control unit includes a current measuring device connected to said data transmission line for detecting and demodulating the data signals supplied by said module.

10. The data transmission system according to claim 9, wherein said module contains a controlled current source for generating the data signals.

11. The data transmission system according to claim 5, wherein said frequency-locked and/or phase-locked loop has an input, and said module includes a comparator having an input connected to said data transmission line and an output connected to said input of said frequency-locked and/or phase-locked loop.

12. The data transmission system according to claim 5, wherein said control unit impresses a d.c. voltage on said data transmission line, and said module includes a voltage regulator having an input connected to said data transmission line and an output outputting a supply voltage for said module.