WO2008107386A1

WO2008107386A1 - Transceiver circuit and controller

Info

Publication number: WO2008107386A1
Application number: PCT/EP2008/052490
Authority: WO
Inventors: Harald Kazmierczak
Original assignee: Robert Bosch Gmbh
Priority date: 2007-03-05
Filing date: 2008-02-29
Publication date: 2008-09-12
Also published as: EP2117886A1; DE102007012708A1

Abstract

The present invention relates to a transceiver circuit (10; 30), comprising: a first connection (LIN/PWMout), which can be connected to a bidirectional communication line and the potential of which can be set to a low level and a high level by a line driver (12, 13); a second connection (PWMin), which can be connected to a unidirectional communication line; a receiving repeater (11), which has an input; and a switching device (16; 17; 22), which has two switch positions, wherein in one switch position the input of the receiving repeater (11) is connected to the first connection (LIN/PWMout) and in the other switch position the input of the receiving repeater (11) is connected to the second connection (PWMin).

Description

description

title

Transceiver circuit and control unit

STATE OF THE ART

The present invention relates to a transceiver circuit and a control device, in particular for controlling electronic components in vehicle systems.

In modern motor vehicles there are a large number of electronic components which can be controlled by one or more central control devices. Examples include the electronic components in the door module, which includes power windows, central locking and electrically adjustable mirrors, but also other comfort elements, such as air conditioning, power seats, overhead lights, electric sunroof, etc.

Originally these components were individually wired. However, the increasing number of electrical components led to a hardly manageable harness, so that standardized bus systems were introduced. One of the most successful bus systems is the CAN bus, an asynchronous serial bus system that works with CS MA / CA and avoids bus arbitration through bit arbitration. A disadvantage of the CAN bus is the relatively large word size and its relatively high cost per node.

As a cheaper alternative to the CAN bus, therefore, the LIN bus standard has been developed. A LIN bus is commonly used in automobiles when the high bandwidth and versatility of CAN is not needed. In a LIN network, there is one LIN master and one or more LIN slaves. Fig. 1 shows the equivalent circuit diagram of the transceiver in a LI N node (master or slave).

As shown in Fig. 1, bidirectional communication is performed via the data line to which the terminal LIN is connected; that is, LIN is a single-wire bus. The signals received at the terminal LIN are passed through an amplifier 1 to a receiving contact RxD. From a transmission contact TxD 2 control signals are applied to the base of a transistor 3, whose emitter is connected to ground and whose collector is connected to the terminal LIN via a resistor. Furthermore, the terminal LIN is connected via a resistor 4 and a diode 5 to a battery line, which leads the operating potential Ubat. Thus, the potential at the terminal LIN between the two operating potentials Ubat and GND can be switched.

Furthermore, data transmission in motor vehicle systems also uses pulse width modulation (PWM). Fig. 2 shows a transceiver for PWM communication. Similar to the LIN bus, signals are sent by switching the potential at the transmission terminal PWMout by driving a transistor 3 'between a high level and a low level. The master transmits a signal at constant frequency with a defined duty cycle ratio via the transmission line. High level and low level are therefore in a certain ratio. However, to receive messages from the slave, a second line is used, which is connected to the PWMin port can. Received signals are supplied to the receiving contact RxD via the amplifier 1 '. Unlike LIN, two lines are required to send and receive signals.

This different design of LIN and PWM meant that the different requirements for the communication could previously only be realized with different components.

ADVANTAGES OF THE INVENTION

Accordingly, a transceiver circuit is provided with:

- A first terminal which is connectable to a bidirectional communication line and whose potential can be set with a transmission driver to a low level and a high level; a second connection connectable to a unidirectional communication line;

a receiving amplifier having an input; and

- A switching device having two switch positions, wherein in one

Switch position of the input of the receiving amplifier is connected to the first terminal and connected in the other switch position, the input of the receiving amplifier to the second terminal.

The idea underlying the transceiver circuit according to the invention is to provide a switching device with which the connection of a connection which can be connected to a bidirectional communication line to the input amplifier can optionally be switched on or interrupted. Depending on the switch position, the Circuit thus be operated as a transceiver for a bidirectional data bus or as a transceiver for two unidirectional communication lines. This results in the significant advantage that both communication options can be realized with only one driver. This means that both functionalities can be realized with only one component, resulting in a reduction of the components to be held in stock as well as the documentation to be provided.

It is advantageous if the switching device is designed as a transistor. This makes it possible to provide the transceiver circuit integrated in a single device.

Furthermore, it is advantageous if the transistor is a MOSFET, since it can then be switched substantially without power.

In an advantageous embodiment, the transmission driver has a bipolar transistor whose collector is connected to the first terminal and whose emitter is grounded. This allows use of the transceiver circuit according to the LIN standard.

A control unit according to the invention for controlling a sensor or actuator via a data bus has the following: the transceiver circuit described above, and

a microcontroller having an input connected to an output of the receive amplifier and having an output connected to the transmit driver.

With such a control device, a transceiver circuit according to the invention can advantageously be integrated with a microcontroller, and thus a control device can be provided be, which has the above features, so for example, both LIN and PWM communication integrated in a device.

In this case, the controller may further comprise an output, via which the control unit provides a control signal, wherein the switch position of the switching device is dependent on the control signal. Thus, a software switch for switching the switching device can be provided.

DRAWINGS

The invention will be explained in more detail with reference to the exemplary embodiments indicated in the schematic figures of the drawings. It shows:

Fig. 1 is a diagram of a transceiver circuit in a LIN module; FIG. 2 is a diagram of a transceiver for PWM communication; FIG.

Fig. 3 shows a transceiver circuit according to the invention, which has the functionality of a

LIN driver combined with that of a PWM driver; 4 shows a control unit according to the invention which comprises the transceiver circuit in FIG. 3; 5 shows a further embodiment of a transceiver circuit according to the invention.

In all figures of the drawings, identical or functionally identical elements - unless otherwise stated - have been provided with the same reference numerals.

3 shows a transceiver circuit 10 according to the invention, which combines the functionality of a LIN driver with that of a PWM driver and, for example, forms part of a control circuit. Circuit can be. In this case, the desired functionality can be selected by means of a switching device 16.

In the closed state, the switching device 16 establishes a connection between a first terminal LIN / PWMout and the input of a receiving amplifier 11, which may be designed, for example, as an operational amplifier, and in the open state the switching device interrupts this connection. Also connected to the receive amplifier 11 is a second terminal PWMin. The output of the receive amplifier 11 is connected to a receive contact RxD. The terminal LIN / PWMout is connected via a resistor 14 and a diode 15 to a battery line, which leads the battery potential Ubat. Furthermore, the terminal LIN / PWMout is connected to the collector of a transistor 13 whose emitter is connected to ground GND. The base of transistor 13 is connected via a resistor 12 to a transmit contact TxD. The transistor 13 and the resistor 12 together form a transmission driver.

In the switch position (a) in FIG. 3, the circuit 10 is operated as a driver for bidirectional data communication via a line connected to the connection LIN / PWMout. The signals received at the terminal LIN / PWMout are transmitted via the amplifier 11 to the receiving contact RxD and further processed there. From the transmitter contact TxD, control signals are applied to the base of the transistor 13 via the resistor 12. Thus, the potential at the terminal LIN / PWMout can be switched between a high level and a low level. In this case, the diode 15 prevents the control circuit from being supplied with power in the event of a local failure of the battery voltage Ubat via the signal line connected to the connection LIN / PWMout. In the switch position (a), the transceiver circuit 10 thus corresponds functionally to the circuit shown in FIG. In the switch position (b) in Fig. 3, the transceiver circuit 10 serves as a PWM driver. The transmission of signals is carried out by the potential at the transmission terminal PWMout is switched by driving the transistor 13 between a high level and a low level. In this case, a signal at a constant frequency with a fixed duty cycle ratio is sent via the transmission line connected to the LIN / PWMout connection (first connection), the high level and the low level being in a specific relationship to one another. Such a PWM driver is widespread, for example, for controlling so-called GPAs (General Purpose Actuators), which receive the electrical energy required for their operation from the vehicle battery and serve to move or position a system within a predetermined work area , Typical examples of this are flap systems, such as the engine on the throttle. Another area of application for PWM is e-gas, where the accelerator pedal transmits the value desired by the driver as an electrical signal to the control unit.

For receiving signals in PWM operation, the second terminal PWMin is provided, which is connected directly to the input of a receiving amplifier 11. Received signals are supplied via the amplifier 11 to the receiving contact RxD. In the switch position (a), the transceiver circuit 10 thus corresponds functionally to the circuit shown in FIG.

A significant advantage of the transceiver circuit shown in Fig. 3 is that with a single component, the functionality of both a LIN driver and a PWM driver can be realized. The LIN / PWMout connector is used both as an output for PWM signals and for LIN signals, so that the number of connections can be reduced compared to a solution in which the LIN driver and the PWM driver are used be housed in parallel on a chip. The circuit shown in Fig. 3 can be used for both masters and slaves in a LIN network. A difference consists only in the dimensioning of the resistor 14, which is 30 kΩ for the slave and only about 1 kΩ for the master.

In its simplest embodiment, the switching device 16 may be formed as a mechanical on / off switch. However, it can also be designed as a semiconductor switch, in particular as a MOSFET. Such a configuration is given in the embodiment shown in Fig. 4.

FIG. 4 shows a control unit 20, which comprises the transceiver circuit 10 in FIG. 3. 4, the same or functionally identical elements as in Fig. 3 are denoted by the same reference numerals and are not explained in detail. The explanations of these elements with respect to FIG. 3 thus also apply analogously to the elements shown in FIG. 4.

In the transceiver circuit 10 in FIG. 4, the switching device 16 is designed as a MOSFET 17. This has the advantage that transceiver circuit 10 can be made monolithic. Source and drain of the MOSFET 17 are respectively connected to the terminal LIN / PWMout and to the input of the receiving amplifier 11. The gate of the MOSFET 17 is supplied by a microcontroller 18, a control signal LIN / PWM, which determines whether the MOSFET 17 is turned on or not conductive. This can be done as a function of a program running on the microcontroller 18, so that the MOSFET 17 can be blocked or switched through by means of a software switch.

The contacts RxD and TxD of the transceiver 10 are connected to the microcontroller 18, where they are fed to a UART device 19. The UART module generates the data bits to be output via the LI N / PWMout connection and the necessary data frames. It converts parallel data to be sent into a serial data stream and generates parallel data from the received serial data stream. The data supplied via the contact RxD to the UART module 19 are fed to a sensor-actuator interface 21, which is connected, for example, to a sensor or actuator to be controlled (not shown here in detail).

FIG. 5 shows a further embodiment of a transceiver circuit 30 according to the invention. In FIG. 5, the same or functionally identical elements as in FIG. 3 are designated by the same reference numerals and will not be explained in detail. The explanations of these elements with respect to FIG. 3 thus also apply analogously to the elements shown in FIG. 5.

In the embodiment shown in Fig. 5, the switching device is designed as a changeover switch 22. As in the arrangement shown in Fig. 3, the circuit 10 is operated in the switch position (a) as a driver for bidirectional data communication via a connected to the terminal LI N / PWMout line, and in the switch position (b), the transceiver circuit 10 as PWM Drivers operated. The arrangement shown in FIG. 5 has the advantage that in LIN operation (switch position (a)), the connection PWMin is separated from the input amplifier 11 and thus can not act on interfering signals from components possibly connected to the connection PWMin.

Although the above embodiments have been described above with reference to preferred embodiments, they are not limited thereto but are modifiable in a variety of ways. For example, the above embodiments have been described for a combination of LIN and PWM functionality. However, the same benefits can also be achieved for other bus systems and data transmission formats. For example, it is also possible to output a frequency-modulated signal instead of PWM signals via the connection LIN / PWMout and thus to set, for example, an actuator (eg the throttle valve) in its operating range. Another option is to output a signal modulated by Frequency Keying or Frequency Shift Keying via the LIN / PWMout connector. In this case, for example, a frequency of 6 MHz for high and a frequency of 4 MHz for low. This has the advantage that signals between master and slave can also be transmitted via an inductive coupling, for example by a transformer. A possible application in the automotive sector is, for example, the communication between steering wheel and steering column.

Claims

claims

1. Transceiver circuit (10; 30) with:

- A first terminal (LIN / PWMout), which is connectable to a bidirectional communication line and whose potential with a transmission driver (12, 13) can be set to a low level and a high level;

- A second terminal (PWMin), which is connectable to a unidirectional communication line;

- A receive amplifier (11) having an input; and

- A switching device (16; 17; 22), which has two switch positions, wherein in a switch position, the input of the receiving amplifier (11) with the first

Connection (LIN / PWMout) is connected and connected in the other switch position, the input of the receiving amplifier (11) to the second terminal (PWMin).

A transceiver circuit (10; 30) according to claim 1, wherein the switching means (16; 17; 22) is formed as a transistor (17).

The transceiver circuit (10; 30) of claim 1, wherein the transistor (17) is a MOSFET.

4. Transceiver circuit (10; 30) according to one of the preceding claims, wherein the transmission driver (12, 13) comprises a bipolar transistor (13) whose collector is connected to the first terminal (LIN / PWMout) and whose emitter is grounded.

5. Control unit (20), in particular for controlling a sensor or actuator via a

A data bus comprising: a transceiver circuit (10; 30) according to any one of the preceding claims, and a microcontroller (18) having an input connected to an output (RxD) of the receive amplifier (11) and having an output connected to the Transmission driver (12, 13) is connected.

6. Control device (20) according to claim 5, further comprising an output via the

Controller provides a control signal (LIN / PWM), wherein the switch position of the switching device 16 is dependent on the control signal (LIN / PWM).