JP2020088564A - OR circuit and electronic control unit - Google Patents

Abstract

To reduce power consumption.SOLUTION: An OR circuit 30 includes a first input end 31, a second input end 32, an output end 33, a first input line 34 connected to the first input end 31, and a second input line 35 connected to the second input end 32. The first input line 34 and the second input line 35 are connected to the output end 33. The first input line 34 includes a resistance element R1. The second input line 35 includes a diode D. The diode D is arranged such that the anode is located on the second input end 32 side and the cathode is located on the output end 33 side.SELECTED DRAWING: Figure 1

Description

The present invention relates to an OR circuit and an electronic control unit.

An OR circuit that outputs a logical sum of two input signals that switch to a low level or a high level as an output signal is described in, for example, Patent Document 1. The OR circuit described in Patent Document 1 is a diode OR circuit composed of two diodes. The output terminal of the OR circuit is grounded via a pull-down resistor.

JP, 2012-222562, A

Depending on the member to which the output end of the OR circuit is connected, the output end of the OR circuit may be connected to the pull-up resistor, so that the output of the OR circuit may be pulled up to the potential of the power supply voltage. In this case, when both of the two input signals input to the OR circuit are Low level, the output signal of the OR circuit is pulled up and the power supply voltage is divided into a pull-up resistor and a pull-down resistor. When both the two input signals input to the OR circuit are Low level, in order to output the Low level output signal from the OR circuit, the resistance value of the pull-down resistor is set lower than the resistance value of the pull-up resistor. There is a need. Then, when a high-level input signal is input from the input terminal of the OR circuit, power consumption increases when a current flows from the output terminal to the pull-down resistor.

An object of the present invention is to provide an OR circuit and an electronic control unit that can reduce power consumption.

An OR circuit for solving the above-mentioned problems includes a first input terminal to which an input signal switching to a Low level or a High level is input, a second input terminal to which an input signal switching to a Low level or a High level is input, and the first A first input line connected to an input end and provided with a resistance element; a second input line connected to the second input end and provided with a diode; and the first input line and the second input line. An output signal which is connected and outputs a logical sum of an input signal input to the first input terminal and an input signal input to the second input terminal and connected to a pull-up resistor for pulling up the output signal The resistance value of the resistance element is lower than the resistance value of the pull-up resistor.

When a Low level input signal is input to both the first input terminal and the second input terminal, the power supply voltage is divided according to the resistance ratio between the pull-up resistor and the resistance element. By setting the resistance value of the resistance element lower than the resistance value of the pull-up resistor, the output signal can be a low-level signal. Even if the output end is connected to the pull-up resistor and the pull-down resistor is not connected to the output end, the OR circuit can output the low-level output signal. Therefore, an increase in power consumption due to the current flowing through the pull-down resistor is suppressed, and low power consumption can be achieved.

An electronic control unit that solves the above problems includes the OR circuit, a transceiver that communicates with a host control device via a bus, a main microcomputer, and a sub-microcomputer that detects an abnormality of the main microcomputer. The transceiver includes a mode terminal connected to the output terminal, and when the low-level output signal is input to the mode terminal, the transceiver enters an operating mode that is a normal communication mode, and the high-level signal is output. When the output signal is input to the mode terminal, the power consumption is lower than that in the operation mode, the standby mode different from the normal communication mode is set, and the main microcomputer is configured to operate at the first input terminal or the second input terminal. And a first terminal for switching the mode of the transceiver by outputting the input signal of the Low level or the High level, and the sub-microcomputer is connected to the first input terminal or the second input terminal. Of these, an input terminal different from the input terminal connected to the main microcomputer is connected, and when the abnormality of the main microcomputer is not detected, the low-level input signal is output to detect the abnormality of the main microcomputer. A second terminal for outputting the High-level input signal when detected is provided.

When the signal input to the mode terminal is low level, the transceiver is in an operation mode which is a normal communication mode, and when the signal is high level, the transceiver is in a standby mode which is different from the normal communication mode. Since the output signal input to the mode terminal is pulled up, when the input signal is not input from the first input terminal and the second input terminal, the mode terminal becomes High level. Therefore, even when the main microcomputer and the sub-microcomputer do not output an input signal due to a reset or the like, the transceiver does not enter the operation mode which is the normal communication mode, but enters the standby mode which is different from the normal communication mode. Therefore, it is possible to suppress malfunction of the host control device that communicates with the transceiver in a state where the main microcomputer and the sub-microcomputer do not output the input signal.

In the electronic control unit, the first terminal of the main microcomputer may be connected to the first input end, and the second terminal of the sub-microcomputer may be connected to the second input end.

When the input signal output by the main microcomputer is at the low level and the input signal output by the sub-microcomputer is at the high level, current flows through the resistance element and power is consumed. The high level input signal is output from the sub-microcomputer when an abnormality of the main microcomputer is detected. Therefore, the frequency at which the high-level input signal is output from the sub-microcomputer is less than the frequency at which the low-level input signal is output. As compared with the case where the first terminal of the main microcomputer is connected to the second input terminal and the second terminal of the sub-microcomputer is connected to the first input terminal, the power consumption can be further reduced.

According to the present invention, low power consumption can be achieved.

The schematic block diagram of an electronic control unit.

Hereinafter, an embodiment of the OR circuit and the electronic control unit will be described.
As shown in FIG. 1, an electronic control unit (ECU) 10 is connected to a host controller 11 via buses L and H. The electronic control unit 10 is mounted on a vehicle and controls onboard components. Although illustration is omitted, a plurality of electronic control units 10 are mounted on the vehicle, and different functions are assigned to each electronic control unit 10. The electronic control unit 10 transmits and receives data to and from the host control device 11 and other electronic control units 10 by performing communication according to a communication protocol such as CAN: Controller Area Network or LIN: Local Interconnect Network. In this embodiment, since CAN is used as the communication protocol, there are two buses, but when LIN is used, there is only one bus. The host controller 11 is an ECU that controls the plurality of electronic control units 10 mounted on the vehicle.

Hereinafter, the electronic control unit 10 will be described in detail.
The electronic control unit 10 includes a main microcomputer 12, a sub-microcomputer 14, a transceiver 20, and an OR circuit 30.

The main microcomputer 12 is a microcomputer that executes processes for realizing the functions assigned to the electronic control unit 10. The transceiver 20 has a function of transmitting the transmission data from the main microcomputer 12 to the upper control device 11 and a function of causing the main microcomputer 12 to receive the reception data from the higher control device 11. It can be said that the transceiver 20 is a network device provided for the main microcomputer 12 to communicate with the host controller 11.

The transceiver 20 includes a transmission terminal TxD, a reception terminal RxD, and a mode terminal MODE. The transmission data from the main microcomputer 12 is input to the transmission terminal TxD. The transceiver 20 converts the transmission data input from the transmission terminal TxD into a differential signal and outputs it to the buses L and H. The transceiver 20 converts the differential signals input from the buses L and H into reception data and outputs the reception data to the main microcomputer 12 from the reception terminal RxD. The differential signal is a signal that represents a dominant or recessive signal level by the potential difference between the buses L and H.

The transceiver 20 switches modes depending on the signal level input to the mode terminal MODE. The transceiver 20 enters the operation mode when a Low level signal, which is a signal having a voltage level lower than a predetermined value, is input to the mode terminal MODE. The transceiver 20 enters the standby mode when a high level signal, which is a signal having a voltage level equal to or higher than a predetermined value, is input to the mode terminal MODE.

The operation mode is a state in which communication can be performed in a normal communication mode. The normal communication mode is a mode in which the transceiver 20 transmits the communication from the upper control device 11 to the main microcomputer 12, and also transmits the communication from the main microcomputer 12 to the higher control device 11. In other words, it is a state in which the transmission data can be converted into a differential signal and the differential signal can be converted into reception data.

The standby mode is a state in which communication is performed in a communication mode different from the normal mode. The communication mode different from the normal mode is a mode in which the transceiver 20 transmits the communication from the upper control device 11 to the main microcomputer 12, but does not transmit the communication from the main microcomputer 12 to the higher control device 11. In detail, in the standby mode, only the minimum circuits necessary to detect a dominant function. That is, it can be said that the standby mode is a state in which the transmission function of the transceiver 20 is stopped until the potential difference between the two buses L and H becomes equal to or greater than the threshold value at which the recessive mode is switched to the dominant mode. The standby mode consumes less power than the operating mode.

The main microcomputer 12 includes a first terminal 13 that outputs an input signal for switching the mode of the transceiver 20. The input signal is a signal that switches to a low level or a high level. The main microcomputer 12 outputs, for example, a low level input signal from the first terminal 13 when the vehicle is in the activated state, and outputs a high level input signal from the first terminal when the vehicle is in the stopped state. The activated state is a state in which the vehicle can be driven by an occupant's operation such as operation of an accelerator pedal. The stopped state is a state in which the vehicle does not run even if the occupant tries to drive the vehicle by operating the accelerator pedal.

When the vehicle is in the activated state, the main microcomputer 12 puts the transceiver 20 in the operation mode in order to communicate with the host controller 11. On the other hand, the main microcomputer 12 reduces the power consumption by setting the transceiver 20 in the standby mode when the vehicle is stopped. It can be said that the main microcomputer 12 puts the transceiver 20 in a standby state when it is not necessary to communicate with the host controller 11.

The sub-microcomputer 14 is a microcomputer provided to detect an abnormality of the main microcomputer 12. The abnormality of the main microcomputer 12 is detected by, for example, a watchdog timer. The main microcomputer 12 resets the watchdog timer by outputting a watchdog pulse every predetermined period. When an abnormality occurs in the main microcomputer 12 and the watchdog pulse is no longer output, the watchdog timer is not reset, so that the sub-microcomputer 14 can detect the abnormality in the main microcomputer 12. The sub-microcomputer 14 includes a second terminal 15 that outputs an input signal. The input signal is a signal that switches to a low level or a high level. The sub-microcomputer 14 outputs a low-level input signal from the second terminal 15 when no abnormality is detected in the main microcomputer 12. When detecting an abnormality in the main microcomputer 12, the sub-microcomputer 14 outputs a high-level input signal from the second terminal 15.

The OR circuit 30 is a logic circuit that outputs a logical sum of two input signals. The OR circuit 30 includes a first input end 31, a second input end 32, an output end 33, a first input line 34 connected to the first input end 31, and a first input line 34 connected to the second input end 32. And two input lines 35. The first input line 34 and the second input line 35 are connected to the output end 33. The first input line 34 includes a resistance element R1. The second input line 35 includes a diode D. The diode D is arranged such that the anode is located on the second input end 32 side and the cathode is located on the output end 33 side.

The first input terminal 31 is connected to the first terminal 13 of the main microcomputer 12. The second input end 32 is connected to the second terminal 15 of the sub-microcomputer 14. The input signal from the main microcomputer 12 is input to the first input terminal 31 of the OR circuit 30, and the input signal from the sub-microcomputer 14 is input to the second input terminal 32 of the OR circuit 30. From the output terminal 33 of the OR circuit 30, the logical sum of the input signal input from the main microcomputer 12 and the input signal input from the sub-microcomputer 14 is output as a Low level or High level output signal.

The output terminal 33 of the OR circuit 30 is connected to the mode terminal MODE. Therefore, the mode of the transceiver 20 is switched by the output signal output from the OR circuit 30. The output signal of the OR circuit 30 is pulled up. More specifically, the transceiver 20 includes a pull-up resistor Ru connected to the plus terminal of the power supply 21, and the mode terminal MODE is connected to the pull-up resistor Ru. The output terminal 33 is connected to the pull-up resistor Ru via the mode terminal MODE, whereby the output signal is pulled up to the potential of the power supply voltage. The resistance value of the pull-up resistor Ru is higher than the resistance value of the resistance element R1. In other words, the resistance value of the resistance element R1 is lower than the resistance value of the pull-up resistance Ru.

The operation of this embodiment will be described.
When a High level input signal is input to at least one of the first input terminal 31 and the second input terminal 32, a High level output signal is output from the output terminal 33 of the OR circuit 30. When a low level input signal is input to both the first input terminal 31 and the second input terminal 32, the power supply voltage is divided according to the resistance ratio between the pull-up resistor Ru and the resistance element R1. By setting the resistance value of the resistance element R1 to be lower than the resistance value of the pull-up resistor Ru, the output signal becomes a low level signal. In this way, the OR circuit 30 can be configured using the diode D and the resistance element R1.

Then, in the electronic control unit 10 using the OR circuit 30 described above, the mode of the transceiver 20 is switched by the output signal of the OR circuit 30. The sub-microcomputer 14 outputs a low-level input signal when an abnormality of the main microcomputer 12 is not detected. In this case, the output signal output from the OR circuit 30 has the same level as the input signal output from the main microcomputer 12. That is, when there is no abnormality in the main microcomputer 12, the main microcomputer 12 can switch the transceiver 20 to an arbitrary mode by switching the input signal to the low level or the high level.

On the other hand, the sub-microcomputer 14 outputs a high-level input signal when detecting an abnormality of the main microcomputer 12. The output signal output from the OR circuit 30 becomes High level regardless of the level of the input signal of the main microcomputer 12. Therefore, when an abnormality occurs in the main microcomputer 12, the output signal of the OR circuit 30 becomes High level, and the mode of the transceiver 20 is switched to the standby mode.

When an abnormality occurs in the main microcomputer 12 while the vehicle is in the activated state, the transceiver 20 is switched from the operation mode to the standby mode. When the transceiver 20 is switched to the standby mode, the communication from the electronic control unit 10 to the host controller 11 is interrupted due to the change of the communication mode. The host controller 11 can determine that an abnormality has occurred in the main microcomputer 12 from the change in the communication mode of the electronic control unit 10.

When the main microcomputer 12 outputs a high level input signal and the sub microcomputer 14 outputs a low level input signal, the OR circuit 30 outputs a high level output signal. In this case, the vehicle is in a stopped state and the sub-microcomputer 14 has not detected an abnormality of the main microcomputer 12. Since the host controller 11 can also know that the vehicle is in the stopped state, in this case, the host controller 11 does not determine that the abnormality has occurred in the main microcomputer 12. That is, the main microcomputer 12 determines that the abnormality has occurred in the higher-level control device 11 when the transceiver 20 is in the standby mode regardless of the activated state of the vehicle.

Further, the main microcomputer 12 and the sub-microcomputer 14 may be reset when the power supply voltage drops excessively. In this case, the main microcomputer 12 and the sub-microcomputer 14 are in the control stop state, and the first terminal 13 and the second terminal 15 are in the high impedance state in which no input signal is output. In this case, the pull-up resistor Ru maintains the output signal input to the mode terminal MODE at the high level. Therefore, the transceiver 20 is prevented from being maintained in the operation mode even when the main microcomputer 12 and the sub-microcomputer 14 are in the control stopped state.

The effects of this embodiment will be described.
(1) Even if the output terminal 33 is connected to the pull-up resistor Ru and no pull-down resistor is provided, the OR circuit 30 can output the low-level output signal. Therefore, it is not necessary to provide a pull-down resistor in the OR circuit 30, an increase in power consumption due to a current flowing through the pull-down resistor is suppressed, and the power consumption can be reduced.

(2) The OR circuit 30 is composed of one diode D and one resistance element R1. The number of diodes can be reduced as compared with an OR circuit using two diodes. When an OR circuit having the same function as the OR circuit 30 of the embodiment is realized by two diodes, the diode is more expensive than the resistance element R1. By forming the OR circuit 30 using the diode D and the resistance element R1, the manufacturing cost can be reduced. Similarly, the manufacturing cost can be reduced as compared with the case where a logic IC is used as the OR circuit 30.

(3) The transceiver 20 is in an operation mode which is a normal communication mode when the signal input to the mode terminal MODE is Low level, and is in a standby mode which is different from the normal communication mode when the signal is High level. Since the output signal input to the mode terminal MODE is pulled up, when the output signal is not input from the output terminal 33, the mode terminal MODE becomes High level. Even when the main microcomputer 12 and the sub-microcomputer 14 do not output an input signal due to a reset or the like, the transceiver 20 does not enter the operation mode which is the normal communication mode, but enters the standby mode which is different from the normal communication mode. Therefore, it is possible to suppress malfunction of the higher-level control device 11 that communicates with the transceiver 20 when the main microcomputer 12 and the sub-microcomputer 14 do not output the input signal.

(4) The first terminal 13 of the main microcomputer 12 is connected to the first input end 31, and the second terminal 15 of the sub microcomputer 14 is connected to the second input end 32. When the input signal output from the main microcomputer 12 is Low level and the input signal output from the sub microcomputer 14 is High level, a current flows through the resistance element R1 and power is consumed. The high level input signal is output from the sub-microcomputer 14 when an abnormality of the main microcomputer 12 is detected. Therefore, the frequency at which the high-level input signal is output from the sub-microcomputer 14 is less than the frequency at which the low-level input signal is output. If the first terminal 13 of the main microcomputer 12 is connected to the second input end 32 and the second terminal 15 of the sub-microcomputer 14 is connected to the first input end 31, a low-level input signal is input to the first input end 31. May be input more frequently and power consumption may increase. On the other hand, by connecting the first terminal 13 of the main microcomputer 12 to the first input terminal 31 and the second terminal 15 of the sub-microcomputer 14 to the second input terminal 32, the first terminal 13 of the main microcomputer 12 is connected to the first terminal 13. Compared to the case where the second input terminal 32 is connected to the second input terminal 32 and the second terminal 15 of the sub-microcomputer 14 is connected to the first input terminal 31, the power consumption is further reduced.

The embodiment can be modified and implemented as follows. The embodiment and the following modifications can be implemented in combination with each other within a technically consistent range.
The first terminal 13 of the main microcomputer 12 may be connected to the second input terminal 32 of the OR circuit 30, and the second terminal 15 of the sub microcomputer 14 may be connected to the first input terminal 31 of the OR circuit 30.

The case where the OR circuit 30 is provided in the electronic control unit 10 has been described as an example, but the OR circuit 30 may be used in a device other than the electronic control unit 10.
When the electronic control unit 10 is mounted on a vehicle other than the vehicle, the electronic control unit 10 may perform communication according to a communication protocol different from the vehicle communication protocol such as CAN.

In the above embodiment, the communication mode different from the normal mode is a mode in which the transceiver 20 transmits the communication from the upper control device 11 to the main microcomputer 12, but does not transmit the communication from the main microcomputer 12 to the higher control device 11. I explained that there is, but it is not limited to this. For example, the transceiver 20 may not transmit the communication from the host controller 11 or the communication from the main microcomputer 12. That is, it is only necessary that some functions are limited and power consumption is low compared to the normal communication mode.

D... Diode, H, L... Bus, MODE... Mode terminal, R1... Resistor element, Ru... Pull-up resistor, 10... Electronic control unit, 11... Upper control device, 12... Main microcomputer, 13... First terminal, 14 ... sub-microcomputer, 15... second terminal, 20... transceiver, 30... OR circuit, 31... first input end, 32... second input end, 33... output end, 34... first input line, 35... second input line.

Claims (3)

A first input end to which an input signal that switches to a low level or a high level is input;
A second input end to which an input signal that switches to a low level or a high level is input;
A first input line connected to the first input terminal and provided with a resistance element;
A second input line connected to the second input terminal and provided with a diode;
The first input line and the second input line are connected to each other, and an output signal that is a logical sum of an input signal input to the first input end and an input signal input to the second input end is output, An output terminal connected to a pull-up resistor for pulling up the output signal,
An OR circuit in which a resistance value of the resistance element is lower than a resistance value of the pull-up resistor. An OR circuit according to claim 1,
A transceiver that communicates with the host controller via the bus,
Main microcomputer,
An electronic control unit comprising a sub-microcomputer for detecting an abnormality of the main microcomputer,
The transceiver is
A mode terminal connected to the output end,
When the low-level output signal is input to the mode terminal, the operation mode is a normal communication mode, and when the high-level output signal is input to the mode terminal, power consumption is lower than that in the operation mode. Low, a standby mode different from the normal communication mode,
The main microcomputer is
A first terminal that is connected to the first input terminal or the second input terminal and that switches the mode of the transceiver by outputting the input signal of the Low level or the High level;
The sub-microcomputer is
It is connected to an input end different from the input end connected to the main microcomputer among the first input end or the second input end, and when the abnormality of the main microcomputer is not detected, the low level An electronic control unit having a second terminal which outputs an input signal and outputs the high-level input signal when an abnormality of the main microcomputer is detected. The first terminal of the main microcomputer is connected to the first input terminal,
The electronic control unit according to claim 2, wherein the second terminal of the sub-microcomputer is connected to the second input end.