JP5369997B2 - In-car communication control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-vehicle communication controller consolidating communication lines without deteriorating a real time performance in communication. <P>SOLUTION: A meter ECU 10 is equipped with: a comparing part 13 for comparing signal levels on a communication line 7 with predetermined two receiving thresholds for magnitude; and a communication IC 12 for reproducing a bit stream on the basis of comparison results by the comparing part 13. For the transmission of the signal on the communication line 7, a binary code (first code) being at a high speed and having large amplitude and a binary code (second code) being at a low speed and having small amplitude are used. The comparing part 15 has: a first comparator 15a for comparing the signal levels by the first receiving threshold which is larger than the amplitude of the second code and smaller than the amplitude of the first code to binarize the signal levels; and a second comparator 15b for comparing the signal levels by the second receiving threshold which is smaller than the amplitude of the second code to binarize the signal levels. Two signals (first code and second code) on the communication line 7, therefore, are separated. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an in-vehicle communication control device that transmits and receives data in an in-vehicle system mounted on a vehicle.

  Conventionally, each electronic control unit (ECU) that controls engines, brakes, power steering, automatic transmissions, etc. (power train system devices), door lock / unlock devices, power windows, meter devices, air conditioners, etc. There is known an in-vehicle system provided with each ECU for controlling (body system device).

  In this type of in-vehicle system, an in-vehicle LAN (Local Area Network) is generally constructed in order to transmit and receive data between the ECUs. For example, for communication between ECUs (hereinafter referred to as power train ECUs) that control power train systems, LANs with relatively high transmission speeds (hereinafter referred to as high speed LANs) are often used. In many cases, a low-speed and inexpensive LAN (hereinafter referred to as a low-speed LAN) is used for communication between ECUs (hereinafter referred to as body-type ECUs) that control the vehicle.

  Of the body ECUs, an ECU that transmits and receives data to and from the power train ECU (hereinafter referred to as a target body ECU) is connected to a communication line for a high-speed LAN in addition to a communication line for a low-speed LAN. By using these two types of communication lines at the same time, the real-time property of communication in the in-vehicle system is ensured.

  By the way, in the target body system ECU, since two types of communication lines are connected, the influence of noise due to crosstalk between these communication lines is regarded as a problem. For this reason, it is considered to consolidate two types of communication lines into a communication line that can be shared by a high-speed LAN and a low-speed LAN (hereinafter referred to as a common line). Further, by consolidating the communication lines, further cost reduction in the in-vehicle system is expected.

  For example, Patent Document 1 includes one comparator that compares a signal level on a shared line with a predetermined reception threshold, and a signal level that exceeds the reception threshold is a high level and a signal level that is equal to or less than the reception threshold. In an ECU that detects a low level, it is disclosed to provide a circuit (level change circuit) that changes a reception threshold according to a signal level on a shared line.

Japanese Patent Laid-Open No. 10-51975

  However, in the conventional apparatus described in Patent Document 1, since the reception threshold value of one comparator is switched and used, a plurality of signals having different high-level signal levels cannot be received simultaneously. There is a problem that the real-time property of communication in the in-vehicle system may be lowered.

  In order to solve the above-described problems, an object of the present invention is to provide an in-vehicle communication control device capable of consolidating communication lines without reducing the real-time property of communication.

  The in-vehicle communication control device according to claim 1, which is an invention made to achieve the above object, includes a connection terminal connected to a transmission line for transmitting a plurality of types of signals having different amplitudes, and a voltage level of the connection terminal. Comparing means for comparing the magnitudes of a plurality of reception threshold values set in advance, and receiving means for reproducing a bit string based on a comparison result by the comparing means.

  Here, for transmission of signals on the transmission line, N types (N is an integer of 2 or more) of transmission rates are used, and a binary code having a larger amplitude is used as the transmission rate is higher. A reception threshold smaller than the binary code having the smallest amplitude among the plurality of reception thresholds is an Nth reception threshold, and a binary code having an i-th largest amplitude (i is an integer between 1 and N−1). A threshold value for reception that is smaller and greater than the binary code whose amplitude is the (i + 1) th largest is defined as the i-th threshold value for reception. Under the above premise, the comparison means compares the voltage level of the connection terminal with the Nth reception threshold value and binarizes it, and compares the voltage level of the connection terminal with the ith reception threshold value to obtain a binary value. The gist is to have a number of comparators corresponding to a plurality of reception threshold values.

  In the in-vehicle communication control apparatus configured as described above, a binary code having a larger amplitude is used for signal transmission as the transmission speed is higher. Therefore, when a plurality of types of signals having different amplitudes are superimposed on the transmission signal. Even in such a case, a high level signal level in a signal having a high transmission rate does not have to be buried in a waveform of a signal having a low transmission rate. A plurality of reception threshold values are set in advance according to the amplitude of the binary code, and the number of comparators corresponding to the reception threshold values is provided. Are simultaneously compared and binarized, so that a plurality of signals (a plurality of types of signals having different amplitudes) transmitted via the same communication line (transmission line) can be separated.

  Therefore, according to the in-vehicle communication control device of the present invention, it is possible to simultaneously receive a plurality of signals having different amplitudes, and therefore it is possible to aggregate communication lines without degrading the real-time property of communication. Further, by consolidating the communication lines, the number of communication lines and terminals (connection terminals) connected to the communication lines can be reduced, so that an increase in cost in an in-vehicle system configured with a plurality of in-vehicle communication control devices Can be suppressed.

  By the way, in the conventional apparatus described in Patent Document 1, since the reception threshold is changed according to the signal level on the communication line (shared line), a signal corresponding to a redundant bit string (that is, a large amount of data) is transmitted. When it is superimposed on the signal, the switching frequency of the threshold value for reception becomes high, so that it is necessary to provide a high-accuracy level changing circuit, and there is a problem that the device design becomes complicated.

  On the other hand, in the in-vehicle communication control device of the present invention, it is not necessary to switch the reception threshold of the comparator, so that it is not necessary to provide a circuit that requires complicated device design, thereby reducing the cost in the in-vehicle system. be able to. In addition, since a plurality of reception threshold values set in advance according to the amplitude of the binary code are used at the same time, a plurality of types of signals having different amplitudes can be received simultaneously regardless of the data amount.

The receiving means includes a detection circuit for detecting an i + 1 high level that is a voltage level that is higher than the i + 1 reception threshold and equal to or lower than the i reception threshold based on the comparison result of the comparison means, and a detection circuit. And holding means for holding the output of the detection circuit during a 1-bit period preset in accordance with the transmission rate of the binary code whose amplitude is the (i + 1) th largest at the timing at which the (i + 1) th high level is detected . .

  Here, in order to make the explanation easy to understand, as shown in FIG. 6, taking the case where the number of reception thresholds is three (N = 3, i = 1, 2) as an example, the receiving means: At a timing when the detection circuit detects a second high level that is higher than the second reception threshold and is equal to or lower than the first reception threshold, and the holding means detects the second high level by the detection circuit, The output of the detection circuit is held only for one bit period corresponding to the binary code having the second largest amplitude.

  The detection circuit detects a third high level that is higher than the third reception threshold and is equal to or lower than the second reception threshold, and the holding unit detects the third high level by the detection circuit. Therefore, the output of the detection circuit is held only for one bit period corresponding to the binary code having the smallest amplitude.

  In other words, in the in-vehicle communication control device configured as described above, since the transmission speed is preset for each signal having different amplitudes, if a signal level (voltage level) within a predetermined range is detected, the signal level is handled. By holding the output of the detection circuit for only one bit period of the signal to be transmitted, it is possible to suppress the disturbance of the output waveform of the detection circuit (particularly undershoot) and the influence of external noise.

Furthermore, in the in-vehicle communication control device of the present invention, as described in claim 2 , the bit string is converted into a binary code having a larger amplitude as the transmission speed is higher, and a plurality of types of signals having different amplitudes are transmitted to the transmission line. It is preferable to provide a transmission means for transmitting through the network.

  In the in-vehicle communication control device configured as described above, in addition to being able to simultaneously receive a plurality of signals (a plurality of types of signals having different amplitudes) transmitted through the same communication line, for example, the reception status (transmission line) Depending on the usage status, a signal of a signal level not used in the transmission line can be transmitted. Furthermore, since a plurality of types of signals having different amplitudes can be transmitted at the same time, the real-time property of communication can be further improved.

The circuit diagram showing the structure of meter ECU10 to which the communication control apparatus in a vehicle was applied. The block diagram showing the whole structure of the vehicle-mounted system 1 provided with meter ECU10. Explanatory drawing showing the relationship between the transmission rate and amplitude in each binary code. Explanatory drawing for demonstrating operation | movement of the latch circuit 16b. Explanatory drawing for demonstrating the determination method of the received signal in meter ECU10. Explanatory drawing which illustrates the relationship between the number of binary codes, and the ordinal number of the threshold value for reception.

Embodiments of the present invention will be described below with reference to the drawings.
<Configuration of in-vehicle system 1>
FIG. 1 is a circuit diagram illustrating a configuration of a meter ECU 10 to which the in-vehicle communication control device of the present invention is applied, and FIG. 2 is a block diagram illustrating an overall configuration of an in-vehicle system 1 including the meter ECU 10.

  As shown in FIG. 2, the in-vehicle system 1 includes an ECU (power train system ECU) 2 that controls an engine, a brake, a power steering, an automatic transmission and the like (power train system device), and a door lock / unlock. Each ECU (body system ECU) 3 for controlling a lock device, a power window, a meter device, an air conditioner and the like (body system device) is provided.

  In the in-vehicle system 1, each ECU 2, 3 has a microcomputer (microcomputer) for controlling a control target device (power train system device, body system device) corresponding thereto, and communication wired in the in-vehicle system 1. And a communication IC for transmitting and receiving data via the line 7. Note that the communication IC is a well-known one that realizes communication by the CSMA / CA method, and even if data of the same bit rate (transmission speed) is simultaneously transmitted from the plurality of ECUs 2 and 3 to the communication line 7, Is configured to transmit data with high priority without colliding.

  In the in-vehicle system 1 of the present embodiment, two types of transmission rates are used for transmission of signals on the communication line 7, and a binary code having a larger amplitude is used as the transmission rate is higher. Specifically, a binary code (hereinafter referred to as a first code) having a high transmission speed and a large amplitude is used for communication between the power train ECUs 2, and a transmission speed is used for communication between the body ECUs 3. A binary code having a low amplitude and a small amplitude (hereinafter referred to as a second code) is used. The communication between the ECU (target body system ECU) 4 that transmits / receives data to / from the power train system ECU 2 and the other ECUs 2 and 3 among the body system ECU 3 is both binary codes (first codes). , Second code) is used. That is, the first code is used for communication between the target body system ECU 4 and the power train system ECU 2, and the second code is used for communication between the target body system ECU 4 and another body system ECU 3. It is done.

  In the following, for ease of explanation, the engine ECU 5 that controls the engine is taken up as the power train system ECU 2, and the door ECU 6 that controls a door lock / unlock device, a power window, and the like as the body system ECU 3, A meter ECU 10 that controls the meter device will be taken up as the target body system ECU 4.

  Of these, although not shown, the engine ECU 5 detects the current vehicle speed based on the vehicle speed sensor that detects the vehicle speed and the sensor signal from the engine speed sensor that detects the engine speed (engine speed). Operation data (bit string) indicating the engine speed is generated, and a signal obtained by converting the bit string into the first code (hereinafter referred to as an operation signal) is transmitted to the meter ECU 10 via the communication line 7.

  Although not shown, the door ECU 6 is based on a sensor signal from a door open / close sensor that detects the open / close state of the door (including a locked / unlocked state) and a window open / close sensor that detects the open / closed state of the power window. Then, state data (bit string) indicating the open / closed state of the door and the power window is generated, and a signal obtained by converting the bit string into the second code (hereinafter referred to as a state signal) is transmitted to the meter ECU 10 via the communication line 7.

  The meter ECU 10 is connected to a combination meter 8 in which a speedometer, a tachometer, a turning light, and various warning light indicators are combined. Based on the operation data received from the engine ECU 5, the current vehicle speed and the engine speed are displayed on the combination meter 8 (speedometer, tachometer), or on the door and power window based on the state data received from the door ECU 6. Display processing for displaying a warning light indicating an open state on the combination meter 8 (display) is executed.

  Further, when the meter ECU 10 cannot restore the operation data based on the first code received from the engine ECU 5, or the meter ECU 10 cannot restore the state data based on the second code received from the door ECU 6, the operation signal And request setting processing for setting data indicating a request for retransmission of the status signal (hereinafter referred to as request data).

<Configuration of Meter ECU 10>
Specifically, as shown in FIG. 1, the meter ECU 10 has data (request data, operation) between the control unit 11 having a microcomputer (not shown) for executing the display process and the request setting process and the engine ECU 5. Data) and the communication IC 12 including the second communication IC 12b that transmits and receives data (request data and status data) to and from the door ECU 6, and a transmission signal from the communication IC 12 is transmitted to the communication line. 7, the connection terminal 14 connected to the communication line 7, the voltage level of the connection terminal 14 (that is, the signal level on the communication line 7), and a plurality of preset values (2 in this embodiment). And a comparison unit 15 that compares the received threshold values with each other and a signal (state signal) corresponding to the state data based on the comparison result by the comparison unit 15 And a signal circuit 16.

  As shown in FIG. 3, a binary code (second code) having a low transmission rate (bit rate) and a small amplitude is used as the status signal (see FIG. 3A). ) As a signal corresponding to the operation data (operation signal), a binary code (first code) having a high bit rate (that is, at a high speed) and a large amplitude is used (see FIG. 3B). For this reason, even if the operation signal is superimposed on the status signal on the communication line 7, for example, the high-level signal level of the high-speed and large-amplitude signal (operation signal) is low-speed and small-amplitude signal ( The state signal is not buried in the waveform (see FIG. 3C).

  Returning to FIG. 1, the comparison unit 15 compares the first reception threshold Vth <b> 1 larger than the amplitude of the second code and smaller than the amplitude of the first code with the signal level on the communication line 7. 1 comparator 15a, and a second comparator 15b that compares the second reception threshold Vth2 smaller than the amplitude of the second code with the signal level on the communication line 7.

  The first comparator 15a sets the signal level above the first reception threshold Vth1 to a high level (first high level) and sets the signal level equal to or lower than the first reception threshold Vth1 to a low level. The level is binarized and a high level or low level signal is output to the first communication IC 12a and the receiving circuit 16. Then, the second comparator 15b binarizes the signal level on the communication line 7 with the signal level higher than the second reception threshold Vth2 as the high level and the signal level equal to or lower than the second reception threshold Vth2 as the low level. A high level or low level signal is output to the receiving circuit 16.

  The reception circuit 16 detects a signal level that is higher than the second reception threshold Vth2 and lower than or equal to the first reception threshold Vth1 as a high level (second high level) based on the comparison result by the comparison unit 15. 16a and a latch circuit 16b that latches the output of the detection circuit 16a only for a 1-bit period that is preset according to the transmission speed of the second code at the timing when the detection circuit 16a detects the second high level. ing.

  Among these, the detection circuit 16a includes an inverter 17 that inverts the signal (waveform signal) waveform-shaped at the high level or low level by the first comparator 15a, the output of the inverter 17, and the output of the second comparator 15b. And a logical product circuit (AND circuit) 18. That is, the detection circuit 16a is configured to detect a high level in the state signal when the output of the second comparator 15b is at a high level and the output of the first comparator 15a is at a low level. Yes.

  The latch circuit 16 b includes a logical sum circuit (OR circuit) 19 and a logical product circuit (AND circuit) 20. If either the output Y of the AND circuit 18 or the output V of the AND circuit 20 is at a high level, the OR circuit 19 supplies a high level to the input of the second communication IC 12b. When the output Z of the second communication IC 12b and the output Q of the second communication IC 12b are both at the high level, the high level is supplied to the input of the OR circuit 19.

  Specifically, in the latch circuit 16b, as shown in FIG. 4, when the output Q of the second communication IC 12b is set to a high level as an initial state, and the detection circuit 16a detects a high level in the state signal. The output Y of the AND circuit 18 becomes a high level, and accordingly, the output Z of the OR circuit 19 becomes a high level. Then, the output of the AND circuit 20 until the above-described 1-bit period (that is, the 1-bit period corresponding to the state signal) elapses and the output Q of the second communication IC 12b is set to the low level as the reset state. (As a result, the output Z of the OR circuit 19) is held at a high level. Note that when the output Q of the second communication IC 12b is set to a low level and a predetermined standby period (a period shorter than the 1-bit period corresponding to the state signal) elapses, the reset state returns to the initial state.

  That is, when the detection circuit 16a detects a high level in the state signal, the latch circuit 16b holds the output of the detection circuit 16a only for one bit period corresponding to the state signal, thereby disturbing the output waveform of the detection circuit 16a. (Especially undershoot) and external noise are suppressed.

  Returning to FIG. 1, the transmission unit 13 converts the transmission signal from the first communication IC 12 a into a first code and transmits it to the communication line 7, and transmits the transmission signal from the second communication IC 12 b to the second code. And a second transmission circuit 13b that converts the code into a communication line 7 and transmits it to the communication line 7.

  The first transmission circuit 13a includes a power source V1 for supplying current to the signal line L1 that connects the first transmission circuit 13a and the connection terminal 14, and the power source V1 (emitter side) to the signal line L1 (collector side). As a unidirectional element connected to the PNP transistor T1 for switching the current path flowing between conductive and non-conductive, the resistor R1 for limiting the base current flowing in the transistor T1, the connection terminal 14 and the collector of the transistor T1. It consists of a diode D1.

  The diode D1 has an anode connected to the connector side of the transistor T1 and a cathode connected to the connection terminal 14 side so that a current can flow from the collector of the transistor T1 toward the connection terminal 14. Further, the power supply voltage of the power supply V1 is set to a value (specifically, a value larger than the first high level) substantially equal to the amplitude (first high level) of the first code.

  That is, in the first transmission circuit 13a, when a low-level transmission signal is output from the first communication IC 12a to the resistor R1, the transistor T1 is turned on and the communication line 7 connected to the signal line L1 via the connection terminal 14 is used. The upper signal level is set to the first high level. On the other hand, when a high-level transmission signal is output from the first communication IC 12a to the resistor R1, the transistor T1 is turned off. If the signal level on the communication line 7 is not high, the signal level on the communication line 7 is low. Configured to level.

  Similarly to the configuration of the first transmission circuit 13a, the second transmission circuit 13b has a power source V2 and a power source V2 (for supplying current to the signal line L2 connecting the second transmission circuit 13b and the connection terminal 14. A PNP transistor T2 for switching a current path flowing from the emitter side) to the signal line L2 (collector side) between conduction and non-conduction, a resistor R2 for limiting a base current flowing through the transistor T2, and a connection terminal 14 and a transistor T2. And a diode D2 as a unidirectional element connected to the collector.

  The diode D2 has an anode connected to the connector side of the transistor T2 and a cathode connected to the connection terminal 14 side so that a current can flow from the collector of the transistor T2 toward the connection terminal 14. Further, the power supply voltage of the power supply V2 is set to a value (specifically, a value larger than the second high level) substantially equal to the amplitude (first high level) of the second code.

  That is, when a low-level transmission signal is output from the second communication IC 12b to the resistor R2, the second transmission circuit 13b turns on the transistor T2 and the signal level on the communication line 7 is not the first high level. The signal level on the communication line 7 connected to the signal line L2 via the connection terminal 14 is set to the second high level. On the other hand, when a high-level transmission signal is output from the second communication IC 12b to the resistor R2, the transistor T2 is turned off. If the signal level on the communication line 7 is not high, the signal level on the communication line 7 is low. Configured to level.

  The first communication IC 12a outputs a high-level or low-level signal (inverted signal) in bit units according to the request data (bit string) for the engine ECU 5 among the setting data (request data) by the control unit 11. 1 is output to the transmission circuit 13a.

  The first communication IC 12a detects the high level in the operation signal when the output of the first comparator 15a is at a high level, and the operation signal when the output of the first comparator 15a is at a low level. By detecting the low level at, the waveform signal from the first comparator 15a is captured. The bit string is reproduced based on the waveform signal, and the received data from the engine ECU 5 is supplied to the control unit 11.

  The second communication IC 12b outputs a high-level or low-level signal (inverted signal) in bit units according to the request data (bit string) for the door ECU 6 among the setting data (request data) by the control unit 11. 2 is output to the transmission circuit 13b.

  In addition, the second communication IC 12b sets the output Q to the AND circuit 20 to a high level as an initial state, and detects the high level at the output Z of the OR circuit 19 (that is, the high level in the state signal). After the elapse of one bit period corresponding to, the output Q to the AND circuit 20 is set to a low level as a reset state. Then, in preparation for detection of a high level in the next state signal, the reset state is returned to the initial state after the above-described standby period has elapsed. Thereby, the waveform signal from the latch circuit 16b is taken in, the bit string is reproduced based on the waveform signal, and the reception data from the door ECU 6 is supplied to the control unit 11.

  The control unit 11 is mainly configured by a microcomputer including a CPU, ROM, RAM, I / O and a bus line connecting them, and the CPU uses the RAM as a work area based on a program stored in the ROM. Then, the display process and the setting request process described above are executed. The data set in the request setting process is supplied to the communication IC 12 and the combination meter 8 (see FIG. 2) is controlled in the display process.

<Operation>
In the meter ECU 10 configured as described above, when the operation data is transmitted from the engine ECU 5 via the communication line 7, the signal level of the operation signal is binarized by the first comparator 15a and the second comparator 15b, Among these, the output of the second comparator 15b is blocked by the detection circuit 16a, and the output of the first comparator 15a is supplied to the first communication IC 12a. Then, the first communication IC 12 a reproduces the bit string based on the signal waveform of the operation signal, and supplies the operation data to the control unit 11.

  In the meter ECU 10, when the state data is transmitted from the door ECU 4 via the communication line 7, the signal level of the operation signal is binarized by the second comparator 15b, and the output of the second comparator 15b is received by the receiving circuit. 16 to the second communication IC 12b. Then, the second communication IC 12 b reproduces a bit string based on the signal waveform of the state signal, and supplies operation data to the control unit 11.

  Alternatively, when the operation data and the state data are transmitted simultaneously and the operation signal is superimposed on the state signal on the communication line 7, the first communication IC 12a detects the operation signal via the first comparator 15a and detects the operation signal. The circuit 16a detects the status signal via the second comparator 15b. Then, the latch circuit 16b holds the output of the detection circuit 16a for one bit period corresponding to the status signal, and the output of the latch circuit 16b is supplied to the second communication IC 12b.

  Accordingly, the bit string based on the signal waveform of the operation signal is reproduced by the first communication IC 12a, the operation data is supplied to the control unit 11, and the bit string based on the signal waveform of the state signal is reproduced by the second communication IC 12b. Operation data is supplied to the control unit 11.

  That is, in the meter ECU 10 configured as described above, as shown in FIG. 5, if the signal level on the communication line 7 is equal to or lower than the second reception threshold Vth2, both the status signal and the operation signal are low. (II) If the value exceeds the second reception threshold value Vth2 and is equal to or less than the first reception threshold value Vth1, the state signal is at a high level and the operation signal is at a low level. judge. And (III) When the signal level on the communication line 7 exceeds the first reception threshold Vth1, it is determined that at least the operation signal is at the high level. Further, (IV) at the timing when the state signal is determined to be at a high level (detection timing of the detection circuit 16a), the output of the detection circuit 16a is held for one bit period corresponding to the state signal.

  Further, in the meter ECU 10, the first communication IC 12a converts the signal into a high level signal or a low level signal in bit units according to the request data for the engine ECU 5, and the first transmission circuit 13a transmits the transmission signal from the first communication IC 12a. Is converted into a first code and transmitted to the communication line 7. The second communication IC 12b converts the signal into a high level or low level signal in bit units according to the request data for the door ECU 6, and the second transmission circuit 13b converts the transmission signal from the second communication IC 12b to the second code. And is transmitted to the communication line 7. As a result, two signals (first code and second code) having different amplitudes can be transmitted simultaneously via the communication line 7.

  In the above embodiment, the comparison unit 15 corresponds to a comparison unit, the communication IC 12 and the reception circuit 16 correspond to a reception unit, the second communication IC 12b and the latch circuit 16b correspond to a holding unit, and the communication IC 12 and the transmission unit 13 correspond to a transmission unit.

<Effect>
As described above, in the meter ECU 10 of the present embodiment, two reception threshold values (first reception threshold value Vth1, second reception threshold value Vth2) are set in advance according to the amplitude of the binary code. Since there are two comparators (first comparator 15a and second comparator 15b) corresponding to each reception threshold, two signals (operation signal and status signal) transmitted through the same communication line 7 Can be separated.

  Therefore, according to the meter ECU 10 of the present embodiment, two signals (operation signal and status signal) having different amplitudes can be received at the same time, so that the communication line 7 is aggregated without reducing the real-time property of communication. be able to.

  Moreover, in meter ECU10, since the 1st transmission circuit 13a and the 2nd transmission circuit 13b are provided independently (separated), two signals (an operation signal, an operation signal, and the like) are provided via the communication line 7. Status signal) can be transmitted simultaneously.

  Further, in the meter ECU 10, since the second communication IC 12b and the latch circuit 16b hold the output of the detection circuit 16a only for one bit period corresponding to the state signal at the detection timing of the detection circuit 16a, the control unit 11 includes the detection circuit 16a. There is no need to regenerate the bit string based on the output, thereby reducing the processing load on the control unit 11.

[Other Embodiments]
As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it is possible to implement in various aspects.

  For example, in the meter ECU 10 of the above embodiment, the first communication IC 12a transmits and receives data to and from the engine ECU 5, and the second communication IC 12b transmits and receives data to and from the door ECU 6. Without being limited thereto, the functions of the two communication ICs 12a and 12b may be configured to be realized by one communication IC.

  Moreover, in meter ECU10 of the said embodiment, although 2nd communication IC12b is comprised so that the output Q to AND circuit 20 may be controlled, it is not limited to this, The function of this 2nd communication IC12b is a control part. 11 may be realized.

  In the meter ECU 10 of the above embodiment, the second communication IC 12b and the latch circuit 16b are configured to hold the output of the detection circuit 16a for one bit period corresponding to the state signal at the detection timing of the detection circuit 16a. However, the present invention is not limited to this. For example, the control unit 11 may perform a process of masking the output of the detection circuit 16a only for one bit period corresponding to the state signal based on the output of the detection circuit 16a. A holding circuit in which transistors are combined may be used.

  Further, in the meter ECU 10 of the above embodiment, the first comparator 15a is configured to output a signal level exceeding the first reception threshold Vth1 as a high level to the first communication IC 12a. A low-pass filter may be provided to suppress disturbance (particularly overshoot) of the output waveform of the detector 15a.

  In the meter ECU 10 of the above embodiment, the PNP transistors T1 and T2 are used for the transmission unit 13, but the invention is not limited to this, and a semiconductor element such as a Pch-MOS may be used, for example. .

  By the way, in meter ECU10 of the said embodiment, two types of signals (1st code | symbol, 2nd code | symbol) are used for transmission of the signal on the communication line 7, and the comparison part 15 uses two threshold values for reception (1st reception data). The number of comparators 15a and 15b corresponding to the threshold value and the second reception threshold value), but is not limited to this. Three or more types of transmission of signals on the communication line 7 are possible. A signal may be used, or the comparator 15 may be configured to have a number of comparators corresponding to three or more reception thresholds. In this case, the receiving circuit 16 may be added according to the increase in the number of comparators.

  In the in-vehicle system 1 of the above-described embodiment, the meter ECU 10 is described as the in-vehicle communication control device. However, the present invention is not limited to this, and various ECUs can be applied as the in-vehicle communication control device.

  DESCRIPTION OF SYMBOLS 1 ... In-vehicle system, 5 ... Engine ECU, 6 ... Door ECU, 7 ... Communication line, 10 ... Meter ECU, 11 ... Control part, 12 ... Communication IC, 12a ... 1st communication IC, 12b ... 2nd communication IC, 13 ... Transmitter, 13a ... First transmitter circuit, 13b ... Second transmitter circuit, 14 ... Connection terminal, 15 ... Comparison unit, 15a ... First comparator, 15b ... Second comparator, 16 ... Receiver circuit, 16a ... Detection Circuit, 16b ... Latch circuit.

Claims (2)

A connection terminal connected to a transmission line for transmitting a plurality of types of signals having different amplitudes;
A comparison means for comparing the voltage level of the connection terminal with a plurality of preset reception threshold values;
Receiving means for reproducing a bit string based on the comparison result by the comparing means;
In-vehicle communication control device comprising:
For transmission of the signal on the transmission line, N types (N is an integer of 2 or more) are used, and a binary code having a larger amplitude is used as the transmission speed is higher.
Among the plurality of reception thresholds, a reception threshold smaller than a binary code having the smallest amplitude is an Nth reception threshold, and a binary code whose amplitude is i-th (i is an integer not less than 1 and not more than N-1). A threshold value for reception which is smaller and whose amplitude is larger than the (i + 1) th largest binary code is set as the i-th threshold value for reception.
The comparison means compares and binarizes the voltage level of the connection terminal with an Nth reception threshold value, and compares and binarizes the voltage level of the connection terminal with an i-th reception threshold value. have a number of comparators corresponding to the plurality of receiving threshold,
The receiving means includes
A detection circuit that detects an (i + 1) th high level that is higher than the (i + 1) th reception threshold and that is equal to or lower than the ith reception threshold based on a comparison result by the comparison unit;
Holding means for holding the output of the detection circuit only for a 1-bit period set in advance according to the transmission rate of the binary code whose amplitude is i + 1th at the timing when the detection circuit detects the (i + 1) th high level; ,
An in-vehicle communication control device comprising: Converts the bit string into a binary code having a large amplitude higher the transmission rate, different plural kinds of signals amplitude, to claim 1, characterized in that it comprises a transmitting means for transmitting via said transmission line The in-vehicle communication control device described.

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