JP2015155259A - communication circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication circuit capable of preventing an unnecessary wake-up operation and suppressing consumption of battery power.

SOLUTION: An electronic control device includes: a data output section for outputting preliminarily fixed transmission data to an external device connected to a communication line when receiving first data from the external device during an operation in a sleep mode; a present time data storage section for storing second data transmitted from the external device in response to the transmission data; a previous time data storage section for storing second data transmitted from the external device before receiving the second data of the present time; a comparison section for comparing the content of the present time data storage section with the content of the previous time data storage section; and a start signal output section for outputting a start signal to shift the operation mode of the electronic control device from the sleep mode to a normal mode on the basis of the comparison result of the comparison section.

COPYRIGHT: (C)2015,JPO&INPIT

Description

  The present invention relates to a communication circuit, and more particularly to a communication circuit included in an electronic control device mounted on a vehicle.

  As a multiplex communication protocol of an electronic control unit (ECU: Electronic Control Unit) in a vehicle, a CAN (Controller Area Network) is used in a powertrain control system that controls an engine and a chassis control system that controls a steering and the like. Also, body control systems that control sensors and actuators such as power windows, mirror adjustments, electric seats, door locks, etc. that require less communication speed and reliability than powertrain control systems and chassis control systems are simple and inexpensive. LIN (Local Interconnect Network) is used.

  In the multiplex communication described above, when a specific signal is sent to the communication bus, the ECU transitions from a sleep mode in which communication is stopped to reduce power consumption to a normal mode in which communication can be performed (wake-up). (Refer patent documents 1 and 2).

  Dominant (dominant) and recessive (inferiority) are defined as signal levels on the communication bus. In the bus idle state in which no signal is generated on the bus, the signal level on the bus is recessive, and when a dominant and recessive are transmitted simultaneously from a plurality of communication devices, the signal level on the bus is dominant. . In general, the dominant logic value is considered as “0: L level”, and the recessive logic value as “1: H level”.

  For example, in the LIN including the master ECU and the slave ECU, when the slave ECU wants to wake up the LIN communication bus, a dominant signal called a wake-up frame is transmitted. The dominant signal is received by the LIN communication driver of the master ECU (hereinafter abbreviated as “LIN driver”), and controls the external interrupt of the CPU and the enable signal of the power supply circuit to start the wake-up operation. .

JP 2012-049885 A JP 2009-532949 A

  FIG. 5 shows an ECU using a LIN driver (that is, a communication circuit) according to the prior art. The LIN is a data communication system in which one master device (ECU1) and one or more slave devices (ECU100, 200) are connected to the same communication line 50. The configurations of the master device and the slave device are almost the same. Therefore, the ECU 1 as the master device will be described as an example.

  The ECU 1 includes a known CPU 2, a LIN driver 3, and a power supply unit 4 that receives power (12 V) from a battery (not shown) and supplies power (5 V) to the CPU 2 and the like. The LIN driver 3 is directly supplied with power from the battery. As the LIN driver 3, for example, there is a TJA1021 made by NXP Semiconductors.

  A storage unit 21 provided in the CPU 2 or in the ECU 1 stores a LIN module that is a control program group for performing LIN communication. By executing the LIN module, the CPU 2 gives the LIN driver 3 an ID for identifying the slave ECU or a data transmission instruction (TX), acquisition of the data received by the LIN driver 3 (RX), and sleep mode. Sleep control (NSLP: NonSleep) for determining whether or not to shift to wakeup, wakeup control for determining whether or not to shift to the normal mode when a wakeup signal is received from the slave device, and the like.

  The LIN driver 3 is configured as a logic circuit, and includes a controller 31 that controls the entire operation, and a signal input / output unit 32 that exchanges signals with the CPU 2. A LIN terminal (for both transmission and reception) is connected to the communication line 50. When an ID or data transmission instruction (TX data) is input from the CPU 2, the controller 31 transmits this to the slave ECU via the communication line 50. Further, when the ID or data is received from the slave ECU, it is output to the CPU 2 as RX data. Further, the state of the INH output is switched based on NSLP from the CPU 2.

  In the normal mode, which is a normal operation mode, the ECU 1 supplies power from the power supply unit 4 to the CPU 2 when the INH output of the LIN driver 3 is in an off state (L level output). When the NSLP output of the CPU 2 changes from an on state (H level output) to an off state (L level output), the LIN driver 3 turns the INH output to an on state (H level output) and supplies power from the power supply unit 4 to the CPU 2. To stop. As a result, the ECU 1 shifts to a stopped state or a sleep mode with low power consumption. Since the LIN driver 3 is directly supplied with power from the battery, the ECU 1 performs the same operation as in the normal mode even when the ECU 1 is in the sleep mode.

  When the LIN driver 3 detects a dominant signal for a predetermined time at the LIN terminal, it determines that this is a wake-up frame, turns off the INH output, and permits the power supply from the power supply unit 4 to the CPU 2. As a result, the CPU 2 transitions from the sleep mode to the normal mode.

  Then, an ID or data (for example, when only “ID” is present, a status inquiry request signal to the slave ECU corresponding to the ID) is transmitted to the slave ECU (100, 200). Based on the response signal of the slave ECU, it is determined whether or not the dominant signal is a wake-up request from the slave ECU. For example, when there is a slave ECU that has transmitted a response signal reflecting the wake-up state, it is determined that the dominant signal is a wake-up request. Thereafter, normal processing is executed.

  On the other hand, when there is no slave ECU that has transmitted a response signal reflecting the wake-up state and it is determined that the dominant signal is not a wake-up request, the CPU 2 changes the NSLP output from the on state (H level output) to the off state. To change. Thereafter, when the controller 31 detects a change in the NSLP output (for example, a falling edge), the controller 31 turns on the INH output (H level output) and stops the supply of power from the power supply unit 4 to the CPU 2. This returns to the sleep mode.

  Therefore, if the external noise similar to the dominant signal is erroneously determined as the dominant signal and the wakeup operation is started, the CPU operates wastefully, and the power consumption of the master ECU increases. Further, since the slave ECU performs useless communication in response to a request signal from the master ECU, the power consumption of the entire LIN also increases. Further, due to the system configuration, other networks connected to the LIN may be woken up. As a result, the current consumption of the entire vehicle system increases, which may cause battery power to be consumed earlier than expected.

  In view of the above problems, an object of the present invention is to provide a communication circuit that can prevent unnecessary wake-up operation and suppress battery power consumption.

  A communication circuit for solving the above problem is included in an electronic control device that performs communication via a communication line, and is a communication circuit that transmits and receives data to and from the communication line. A normal mode that is in the normal state and a sleep mode that is an operating state that consumes less power than the normal mode, and a communication unit that is operating in the sleep mode. When the first data is received from the external device connected to the data output unit, the data output unit that outputs predetermined transmission data to the external device, and the second data transmitted from the external device in response to the transmission data The current data storage unit to store, the previous data storage unit to store the second data transmitted from the external device before receiving the current second data, the contents of the current data storage unit and the previous data storage A comparison unit that compares the contents of the unit, and an activation signal output unit that outputs an activation signal for shifting the operation mode of the electronic control device from the sleep mode to the normal mode based on the comparison result of the comparison unit .

  With the above configuration, unnecessary wake-up operation due to noise can be suppressed, and only reliable data other than noise can be transmitted and received between ECUs (electronic control units).

  The consumption current during the wake-up of the CPU per ECU is about 100 mA, and the configuration of the present invention can reduce the battery load by suppressing unnecessary wake-up operation due to external noise. About 30 LIN-connected ECUs are mounted, and the effect of reducing battery power consumption is not small.

  When the battery runs out, the engine cannot be started, and there is a possibility that each system (particularly, a system related to security) installed in the vehicle may not operate. In other words, there is a possibility that the use of the vehicle may be hindered by intentionally radiating electromagnetic waves (that is, noise) to wake up the ECU and drain the battery. In the configuration of the present invention, as described above, unnecessary battery power consumption is suppressed, so that these situations are less likely to occur.

The figure which shows the structure of the electronic control apparatus using the communication circuit of this invention. The figure which shows the flow of a master / slave determination operation. The figure which shows the flow of the wakeup operation | movement when operate | moving as a master apparatus. The figure which shows the flow of the wakeup operation | movement when operate | moving as a slave apparatus. The figure which shows the structure of the electronic control apparatus using the communication circuit of a prior art.

  FIG. 1 shows a configuration of an ECU 1 (an electronic control device of the present invention) using a communication circuit of the present invention. Of the configurations of the present invention, the same configurations as those in FIG. 5 described above are given the same reference numerals, and detailed descriptions thereof are omitted. The main difference from FIG. 5 is that the LIN driver 3 executes the wakeup determination performed by the CPU 2 and data transmission at the time of the wakeup determination. For this reason, the LIN module stored in the storage unit 21 does not include a wakeup determination process.

  The LIN driver 3 (communication circuit of the present invention) includes, for example, a nonvolatile memory in addition to the controller 31 (discrimination unit, data output unit, activation signal output unit of the present invention) and signal input / output unit 32 (data acquisition unit of the present invention). It further includes a transmission data storage unit 33, a current data storage unit 34, a previous data storage unit 35, and a comparison calculator 36 also called a digital comparator.

  The transmission data storage unit 33 (data output unit of the present invention) is an ID (for identifying the slave ECU) or data necessary for communication in the sleep mode, and whether the ECU 1 is a master device / slave device Stores information, last transmitted / received ID or data.

  The current data storage unit 34 stores data received in the current communication. The previous data storage unit 35 stores the data received in the previous communication. That is, when new data is received, the data stored in the current data storage unit 34 is stored in the previous data storage unit 35, and the new received data is stored in the current data storage unit 34.

  The comparison computing unit 36 (comparison unit of the present invention) compares the contents of the current data storage unit 34 and the previous data storage unit 35 and outputs the result (match / mismatch).

  A master / slave determination flow in the controller 31 will be described with reference to FIG. First, when TX data is input from the CPU 2 (S11: Yes), the contents (data length, data structure, etc.) of the TX data are analyzed (S12). Based on the analysis result, it is determined whether the ECU 1 including the LIN driver 3 is a master device or a slave device (S13). Finally, based on the determination result, the configuration (data length or data content) of data to be transmitted in the sleep mode is determined (S14).

  The configuration shown in FIG. 2 includes “a data acquisition unit that acquires data to be transmitted to an external device, and the electronic control device is either a master device or a slave device based on the content of the data acquired by the data acquisition unit. It is provided with a setting unit for setting whether to operate ". With this configuration, the communication circuit of the present invention can be used for either a master device or a slave device, and the circuit can be shared.

  A flow of a wake-up operation in the controller 31 when the ECU 1 is a master device will be described with reference to FIG. Assuming that the ECU 1 is in the sleep mode, the ECU 1 is in a waiting state for a wakeup frame (first data of the present invention). When the ECU 1 is a master device, the ECUs 100 and 200 are slave devices (external devices).

  First, when a wakeup frame is detected (S31: Yes), an ID (status transmission request, transmission data of the present invention) is transmitted to the slave device. The slave device (LIN driver) that has received its own ID transmits to the ECU 1 the state of the slave device (whether it is waked up or second data of the present invention).

  When the ECU 1 receives data from the slave device (slave device state) (S33: Yes), the ECU 1 stores the data stored in the current data storage unit 34 in the previous data storage unit 35, and stores the received data in the current data storage. The data is stored in the unit 34 (S34). These data are stored in association with the ID (that is, the slave device). Subsequently, for each ID, the comparison calculator 36 compares the contents of the current data storage unit 34 and the previous data storage unit 35 (S35).

  The received data includes data reflecting the state of the slave device, that is, the operation mode (normal mode / sleep mode). In the data comparison, it is checked whether or not the operation mode has changed (that is, whether or not the mode has changed from the sleep mode to the normal mode).

  The ECU 1 itself cannot transition to the sleep mode unless all the slave devices transition to the sleep mode. That is, the previous data storage unit 35 includes information reflecting that the slave device has transitioned to the sleep mode, or information reflecting allowing the ECU 1 to transition to the sleep mode.

  The above-described configuration is “the data received from the external device is stored in the previous data storage unit immediately before the electronic control device shifts to the sleep mode”. With this configuration, if data indicating that the external device has transitioned to the sleep state is stored in the data storage unit this time, the state change of the external device can be detected.

  As a result of the comparison, when both match and there is no change in the data content, that is, when all the slave devices maintain the sleep mode (S36: No), the determination operation ends. That is, the sleep mode is maintained. On the other hand, when there is a change in the data content, that is, when it is determined that one of the slave devices wakes up and shifts to the normal mode (S36: Yes), the output of the comparison calculator 36 is turned on (H level). Output) (S37). As a result, the INH output changes from the on state (H level output) to the off state (L level output), and the start signal of the present invention is output.

  The above-described configuration is “the activation signal instructs the power supply unit that supplies power to the electronic control device to supply / shut off power”. With this configuration, the operation mode can be switched with a relatively simple configuration of power supply / shutoff.

  Thereafter, the CPU 2 wakes up, and the ECU 1 shifts from the sleep mode to the normal mode. Thereafter, based on an instruction (TX data) from the CPU 2, the ID or data is transmitted to the slave device (S38).

  The configuration of FIG. 3 is “when the electronic control device is a master device, the first data requests the electronic control device to transition from the sleep mode to the normal mode, and the transmission data is the external device. The second data reflects the status of the external device, and the current data storage unit and the previous data storage unit identify the status of the external device and identify the external device. The information is stored in association with the information, and the comparison unit compares the state of the external device stored in each data storage unit for each external device. With this configuration, when the master device receives a wake-up request, it can be determined whether this is from a slave device or noise, so unnecessary wake-up operations can be suppressed.

  The flow of the wake-up operation in the controller 31 when the ECU 1 is a slave device will be described with reference to FIG. It is assumed that the ECU 1 is in the sleep mode. When the ECU 1 is a slave device, one of the ECUs 100 and 200 is a master device (external device).

  As shown in FIG. 3, when the master device detects a wakeup frame, it transmits an ID (status transmission request, first data of the present invention) to the slave device. When receiving the ID (S51: Yes), the ECU 1 transmits data (transmission data of the present invention) reflecting the current operation mode of the ECU 1 to the master device (S52). Whether the ECU 1 is in the sleep mode or the normal mode can be determined by the NSLP input state to the controller 31.

  After this, when the ID or data (second data of the present invention) is not received from the master device (S53: No), the wakeup frame detected by the master device is noise and any slave device is waked up. Since there is no, the determination operation is terminated.

  On the other hand, when an ID or data is received from the master device (S53: Yes), the data stored in the current data storage unit 34 is stored in the previous data storage unit 35, and the received data is stored in the current data storage unit 34. (S54). Subsequently, the comparison calculator 36 compares the contents of the current data storage unit 34 and the previous data storage unit 35 (S55).

  The above-described configuration is “the data received from the external device is stored in the previous data storage unit immediately before the electronic control device shifts to the sleep mode”. With this configuration, if data indicating that the external device has transitioned to the sleep state is stored in the data storage unit this time, the state change of the external device can be detected.

  As a result of the comparison, when the two match and there is no change in the data contents, that is, when there is no wakeup request from the master device (S56: No), the determination operation is terminated. That is, the sleep mode is maintained. On the other hand, when there is a change in the data contents, that is, when there is a wakeup request from the master device (S56: Yes), the output of the comparison computing unit 36 is turned on (H level output) (S57). As a result, the INH output changes from the on state (H level output) to the off state (L level output), and the start signal of the present invention is output.

  The above-described configuration is “the activation signal instructs the power supply unit that supplies power to the electronic control device to supply / shut off power”. With this configuration, the operation mode can be switched with a relatively simple configuration of power supply / shutoff.

  Thereafter, the CPU 2 wakes up, and the ECU 1 shifts from the sleep mode to the normal mode. Thereafter, based on an instruction (TX data) from the CPU 2, the ID or data is transmitted to the master device.

  The configuration of FIG. 4 is “when the electronic control device is a slave device, the first data requests transmission of the state of the electronic control device, and the transmission data reflects the state of the electronic control device. The second data is predetermined data from an external device, and the comparison unit compares the contents of the predetermined data stored in the respective data storage units. With this configuration, when the slave device receives the first data, it can be determined whether this is from the master device or noise, so unnecessary wakeup operations can be suppressed.

  Further, the configuration of FIG. 3 and FIG. 4 is as follows: “In a data communication system in which at least one master device and a plurality of slave devices are connected to the same communication line, when the electronic control device is a master device, the external device is a slave. When the device and the electronic control device are slave devices, the external device is the master device. With this configuration, the communication circuit of the present invention can be used for either a master device or a slave device, and the circuit can be shared.

  Although the embodiments of the present invention have been described above, these are merely examples, and the present invention is not limited to these embodiments, and the knowledge of those skilled in the art can be used without departing from the spirit of the claims. Various modifications based on this are possible.

1 ECU (electronic control unit)
3 LIN driver (communication circuit)
31 controller (discriminating unit, data output unit, start signal output unit)
32 Signal input / output unit (data acquisition unit)
33 Transmission data storage unit (data output unit)
34 Current data storage unit 35 Previous data storage unit 36 Comparison calculator (comparison unit)

Claims (6)

A communication circuit that is included in an electronic control device that performs communication via a communication line, and that transmits and receives data to and from the communication line,
A discriminator for discriminating in which operation mode the electronic control device is operating in a normal mode that is a normal operation state and a sleep mode that is an operation state that consumes less power than the normal mode;
A data output unit that outputs predetermined transmission data to the external device when receiving the first data from the external device connected to the communication line when operating in the sleep mode;
A current data storage unit for storing second data transmitted from the external device in response to the transmission data;
Before receiving the second data of this time, a previous data storage unit that stores the second data transmitted from the external device;
A comparison unit that compares the content of the current data storage unit with the content of the previous data storage unit;
An activation signal output unit that outputs an activation signal for transitioning the operation mode of the electronic control device from the sleep mode to the normal mode based on the comparison result of the comparison unit;
A communication circuit comprising: In a data communication system in which at least one master device and a plurality of slave devices are connected to the same communication line,
When the electronic control device is the master device, the external device is the slave device,
The communication circuit according to claim 1, wherein when the electronic control device is the slave device, the external device is the master device. A data acquisition unit for acquiring data for transmission to the external device;
The communication circuit according to claim 2, further comprising: a setting unit configured to set whether the electronic control device operates as the master device or the slave device based on content of data acquired by the data acquisition unit. When the electronic control device is the master device,
The first data is a request for the electronic control device to transition from the sleep mode to the normal mode,
The transmission data is for requesting transmission of the state of the external device,
The second data reflects the state of the external device,
The current data storage unit and the previous data storage unit store the state of the external device in association with identification information for identifying the external device,
The communication circuit according to claim 2, wherein the comparison unit compares the state of the external device stored in each data storage unit for each external device. When the electronic control device is the slave device,
The first data is for requesting transmission of the state of the electronic control unit,
The transmission data reflects the state of the electronic control device,
The second data is predetermined data from the external device,
The communication circuit according to claim 2 or 3, wherein the comparison unit compares the contents of the predetermined data stored in the respective data storage units.   The communication circuit according to any one of claims 1 to 5, wherein the previous data storage unit stores data received from the external device immediately before the electronic control device shifts to the sleep mode. .

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