Vehicle communications network transceiver, transmitter circuit therefor

• US 5,337,042 A
• Filed: 09/28/1992
• Issued: 08/09/1994
• Est. Priority Date: 09/28/1992
• Status: Expired due to Term

• Current Assignee: Chrysler Group LLC (Stellantis NV)
• Original Assignee: Chrysler Corporation (Stellantis NV)
• Inventors: Miesterfeld, Frederick O., Hormel, Ronald F.
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): ZIMMERMAN, BRIAN A
• Application Number:
  US07/951,988
• Time in Patent Office: 680 Days
• Field of Search: 340/825.08, 340/825.63, 375/22, 307/517, 307/234, 328/58
• US Class Current: 340/3.51
• CPC Class Codes: B60R 16/0315 using multiplexing techniques multiplexing for transmission of signals G08C15/00; multiplexing for electrical communication in general H04J
• CPC Class Codes: H04B 14/026 using pulse time characteristics modulation, e.g. width, position, interval
• CPC Class Codes: H04L 25/0278 Arrangements for impedance matching
• CPC Class Codes: H04L 25/028 Arrangements specific to the transmitter end
• CPC Class Codes: H04L 25/0292 Arrangements specific to the receiver end

Abstract

A transceiver device for use with a microcontroller and a symbol encoder decoder device (forming a node in a communications network) for transmitting and receiving variable pulse width modulated (VPWM) analog signals containing symbol messages over a communications bus. The transceiver accepts digital VPWM signals from the symbol encoder decoder device which were generated by the microcontroller and converts the digital signals into VPWM analog signals and then transmits the analog signal over the bus to other nodes. The transceiver also receives VPWM analog signals placed on the bus by other nodes of the network and transfers the signals in digital form to the symbol encoder decoder device which, in turn, communicates the decoded messages to the microcontroller.

Claims

1. A transceiver in nodes of a multiple node vehicle communications network having a communications bus prescribed for use in an automotive industrial standard data link, interconnecting the nodes, each node providing means for translating a chosen measurand into digital pulses appearing at varying rates in response to changes of the measurand into symmetrical, variable pulse width modulated (VPWM) trapezoidal shaped waveform signals containing symbol information expressing the magnitudes of the measurand, each node containing a regulated power source connected to a vehicle battery to provide regulated logic voltages referenced with respect to a signal ground return;

each node also containing a microcontroller (MCU) connected between the input device and a symbol encoder decoder (SED) for receiving signals representing magnitudes of the measurands, formatting the received signals into digital messages, polling input and output ports connected to the SED, and initiating transmission over the bus via the SED, the SED being interconnected between the MCU and the transceiver for translating the digital messages from the MCU into variable pulse width modulated (VPWM) square wave line codings sent to other transceivers connected to the bus and for converting square wave digital signals received from other transceivers into digital messages used by the MCU for updating or controlling other peripherals associated with the network, said transceiver comprising;

(a) an integrator with an input for receiving the VPWM square-wave pulses from SED having pulse widths that define symbol information with respect to time and logic levels and producing at an output terminal trapezoid type waveform signals with pulses 180 degrees out of phase with the square wave pulses and referenced with respect to a fixed voltage level;

(b) a waveshaper having an input for receiving the trapezoid waveform signals from the integrator and reshaping both corners at the extremities of each edge of the pulses over a chosen duration and then producing at an output terminal other trapezoid waveform signals in phase with the input waveform signals having the same pulse width as the input trapezoid signals at trip point voltage so as to retain the symbol information contained in the original square-wave signals, the reshaped trapezoid signals being referenced with respect to another fixed voltage level;

(c) a voltage-to-current converter having an input for receiving the reshaped trapezoid waveform signals from the waveshaper, and providing at an output a replica of the reshaped trapezoid waveform signals as control current source signals, said control current source signals being routed to a current sensor circuit within the voltage-to-current converter to provide pulse voltage potentials with respect to signal ground return of magnitudes proportional to the voltage across the current sensor;

(d) a bus driver connected between the battery of the vehicle and the signal ground return having an input for receiving the pulse voltage potentials from said voltage-to-current converter and producing at a single-ended output amplifications of the reshaped trapezoid pulse signals referenced with respect to the signal ground return which route over the bus to other listening nodes, said amplified signal retaining the symbol information contained in the original square-wave pulse signals; and

(e) a receiver circuit interconnected between the bus and SED for receiving reshaped trapezoid waveform signals from the bus and extracting symbol information contained in the waveform signals and converting the extracted symbol information into digital pulse signals with pulse durations equivalent to the symbol information.

2. Apparatus as defined in claim 1 wherein the communications bus is a twisted pair wire bus.

3. Apparatus as defined in claim 1 wherein the symbol information remains constant in the reshaped trapezoid waveform signals received by each receiver in each transceiver despite the fact the symbol information in the reshaped trapezoid pulses relates to the signal ground returns in each node.

4. Apparatus as defined in claim 1 wherein the integrator includes circuits for lengthening the rise and fall times of the edges of the input square wave pulses to produce symmetrical rise and fall time slopes about a chosen maximum pulse amplitude location and wherein the amplitudes of the pulses being bounded are at chosen voltage levels.

5. Apparatus as defined in claim 4 wherein the waveshaper provides gain and controlled gain reduction operations so as to further round the corners of the pulses at the extremities of each edge in forming the reshaped trapezoid pulses and wherein the provided gain produces bounding of the pulses at a chosen voltage amplitudes greater than the amplitudes of the bounded pulses from the integrator.

6. Apparatus as defined in claim 5 wherein the bus driver output pulses have amplitudes of a chosen multiple of the amplitude of the pulses across the sensor in the current-to-voltage converter.

7. Apparatus as defined in claim 6 wherein the chosen multiple of the amplitude of the driver output pulses is about four times that of the amplitude of the output pulses from the current-to-voltage converter.

8. A node transceiver of a multinode network having a communications bus interconnecting the nodes permitting asynchronous communication between nodes providing to the network information from input devices such as sensors and switches, each node connected to the bus having (1) a regulated power source connected to a fixed voltage to provide regulated logic voltages referenced with respect to a signal ground return, (2) a microcontroller (MCU) connected between the input devices associated with the node, a symbol encoder decoder (SED) and the regulated power source for receiving signals representing magnitudes of the measurands, formatting the received signals into digital messages, polling input and output ports connected to the SED, and initiating transmissions over the bus by controlling the operations of SED, and (3) the SED interconnected between the MCU and the transceiver for translating the digital messages from the MCU into variable pulse width modulated square-wave signals sent to other transceivers connected to the bus and for converting the square-wave digital signals received from other transceivers into digital messages used by the MCU for updating or controlling other peripherals associated with the network, said transceiver comprising:

A. integrating means for converting the VPWM square-wave pulse signals received from SED into a decreased amplitude, 180 degrees out-of-phase trapezoid waveform signals referenced with respect to bounding fixed voltage levels, the trapezoid waveform signals having consistent pulse widths at chosen trigger points which continues to define the symbol information placed in the original square-wave pulses;

B. waveshaper means coupled to the integrator means for intercepting and then reshaping the corners at the extremities of each edge of the pulses of the trapezoid waveform signals, and providing gain and controlled gain reduction parameters, yet retaining the consistent pulse width at the trigger points of the pulses;

C) voltage-to-current converter means for using the reshaped trapezoidal waveform signals to provide varying control current source signals with respect to signal ground return in response to changes in amplitude and duration of the reshaped trapezoid waveform pulse signals; and

D) bus driver means responsive to the varying control current source signals for proving amplified reshaped pulse signals which route to the bus providing symbol messages on the bus that minimizes electromagnetic interference in the vehicle.