JP2022131931A - Start control device - Google Patents

Abstract

To provide a start control device that can operate a communication circuit effectively.SOLUTION: In an ECU 10, when a signal detection circuit 28 detects a communication signal S input through a communication line 18, an output signal D changes. In a latch circuit 32, the output signal D is input as a set signal Rs. In the latch circuit 32, when the output signal D changes, latching is performed and a transistor 30 is turned on. When the transistor 30 is turned on, a communication circuit 16 is connected to an electric power source and started. Thus, in the ECU 10, since the communication circuit 16 is started not through a microcomputer 12, the communication circuit 16 can be operated effectively.SELECTED DRAWING: Figure 1

Description

The present invention relates to an activation control device.

Patent Document 1 discloses an ECU including a power management CPU, a G/W-CPU, and a power supply IC. In the ECU, a power supply IC is composed of a CPU and memory such as ROM and RAM, and a circuit function is realized by executing a software program.

In this power supply IC, for example, when a signal is input from a CAN network, the signal output from the WKUP detection circuit 3 is input to the OR circuit of the wakeup/sleep determination circuit. The OR circuit outputs a wakeup signal to the output signal control circuit when the signal is input. As a result, in the ECU, the output voltages of the 5V regulator and the 1.5V regulator are supplied to the power management CPU and G/W-CPU, and the reset signal to the power management CPU and G/W-CPU is set to H level. CAN communication of the power management CPU and G/W-CPU becomes possible.

JP 2007-030593 A

By the way, some ECUs (electronic control units) are provided with a communication circuit together with a microcomputer, and the communication circuit uses an active element and operates when a predetermined power is supplied. In the ECU, when the microcomputer detects a communication signal input from another ECU, the communication circuit is activated by controlling to connect the power supply to the communication circuit. However, when the microcomputer detects a signal input from another ECU and controls to supply power to the communication circuit, it takes time for the communication circuit to operate (start) after the signal for communication is input. Resulting in.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an activation control device capable of effectively operating a communication circuit provided in an electronic control device.

An activation control device according to a first aspect for achieving the above object is provided in an electronic control device together with a microcomputer, operates by being supplied with power, and is an external device connected to the electronic control device by a signal line. and the microcomputer, a switching element capable of supplying the power to the communication circuit when operated, and a signal for communication on the signal line and a detection circuit that detects a change in the detected signal and outputs a detection signal corresponding to the detected signal change. a latch circuit into which a signal is input as the latch signal.

According to a second aspect of the activation control device, in the first aspect, the latch circuit is unlatched by a release signal output from the microcomputer to de-energize the switching element to the communication circuit.

In the activation control device according to a third aspect, in the first aspect, the latch circuit can output a latch release signal for de-energizing the switching element to the communication circuit, It includes a latch release circuit for outputting the latch release signal when the non-changed state reaches a predetermined time at which it is determined that the communication between the microcomputer and the external device has ended.

A fourth aspect of the activation control device according to the third aspect is that the detection circuit outputs a determination signal indicating whether or not a series of signal receptions or signal transmissions is detected based on the change state of the signal in the detection signal. A continuation determination circuit for outputting is included, and the latch release circuit outputs the latch release signal based on the elapsed time after it is determined from the determination signal that the series of signal receptions or signal transmissions has ended.

According to a fifth aspect of the invention, in any one of the first to fourth aspects, the detection signal of the detection circuit is output to the microcomputer as an activation signal.

A start control device of a sixth aspect is the activation control device according to the fifth aspect, wherein the microcomputer includes an input terminal for inputting a reception signal and an output terminal for outputting a transmission signal, and the detection signal of the detection circuit is input to the input terminal.

In the activation control device of the first aspect of the present invention, the communication circuit is provided in the electronic control device together with the microcomputer. and a microcomputer. Power is supplied to the communication circuit by operating a switching element, and the switching element is operated by inputting a latch signal to a latch circuit (self-holding circuit).

Here, the detection circuit detects a change in a signal for communication on the signal line and outputs a detection signal according to the detected signal change. The detection signal of the detection circuit is input to the latch circuit as a latch signal. As a result, when the detection circuit detects a signal for communication, power is supplied to the communication circuit and the communication circuit is activated. time can be shortened.

In the activation control device of the second aspect, the latch circuit is released by the release signal output from the microcomputer, and the switching element stops supplying power to the communication circuit. As a result, the communication circuit can be stopped by the microcomputer, so that the operation of the communication circuit can be stopped accurately after the microcomputer finishes communication.

In the activation control device of the third aspect, the latch of the latch circuit is released by the latch release signal output by the latch release circuit, and power is not supplied to the switching element to the communication circuit. Further, the latch release circuit outputs a latch release signal when the non-change state of the detection signal reaches a predetermined time at which it is determined that the communication between the microcomputer and the external device has ended.

This eliminates the need for output terminals (leads) for outputting signals for operating the communication circuit to the microcomputer chip and signals for stopping the operation of the communication circuit. The number of terminals for connecting to equipment can be reduced, and the size of the microcomputer chip can be reduced (downsized).

In the activation control device of the fourth aspect, the continuation determination circuit outputs a determination signal indicating whether or not a series of signal receptions or signal transmissions has been detected based on the change state of the signal in the detection signal. Further, the unlatch circuit outputs a latch unlatch signal based on the elapsed time after it is determined in the determination signal output by the continuation determination circuit that the series of signal receptions or signal transmissions has ended.

Here, in a series of signal receptions or transmissions, the detection circuit continuously detects the signals, and the continuation determination circuit outputs a determination signal for determining that the signal transmission or reception is continuing. Further, the continuation determination circuit outputs a determination signal for determining that the transmission or reception of the signal is continued from the elapsed time after the detection circuit stopped detecting the signal (became in a non-detection state).

This makes it possible to effectively determine from the detection signal of the detection circuit that the communication between the microcomputer and the external device has ended.

In the activation control device of the fifth aspect, the detection signal of the detection circuit is output to the microcomputer as the activation signal. As a result, the microcomputer can be activated together with the communication circuit, so that even in the sleep state in which activation of the microcomputer is stopped, communication can be quickly made possible.

In the activation control device of the sixth aspect, the microcomputer includes an input terminal for inputting the reception signal and an output terminal for outputting the transmission signal, and the detection signal of the detection circuit is input to the input terminal. As a result, the number of terminals of the microcomputer can be further reduced, and the size of the microcomputer chip can be further reduced.

1 is a schematic configuration diagram of an ECU according to a first embodiment; FIG. (A) to (G) are timing charts relating to activation of communication circuits in the ECU of the first embodiment. FIG. 5 is a schematic configuration diagram of an ECU according to a second embodiment; FIG. (A) to (H) are timing charts relating to activation of the communication circuit in the ECU of the second embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First embodiment]
Vehicles are equipped with multiple ECUs (Electronic Control Units). In vehicles, multiple ECUs connected to each other via communication lines work together to control driving and other functions. Various controls are performed. FIG. 1 is a block diagram showing a schematic configuration of an ECU 10 as an electronic control unit according to the first embodiment.

The ECU 10 includes a microcomputer (microcomputer) 12 , and the ECU 10 has a chip of the microcomputer 12 attached to a substrate 14 . The ECU 10 also includes a communication circuit 16. The communication circuit 16 is formed on the substrate 14, and a communication line (communication line) 18 as a signal line is connected to another ECU (not shown) as an external device. connected by In the ECU 10, the microcomputer 12 executes a predetermined program including a communication program. Further, the microcomputer 12 performs bidirectional communication (data transmission/reception) with microcomputers of other ECUs via the communication circuit 16 according to a predetermined communication protocol by executing a communication program. Note that the communication between the microcomputer 12 and the microcomputers of other ECUs may be at least as long as the microcomputer 12 receives transmission signals from the microcomputers of the other ECUs.

A plurality of pins (leads) 20 are formed on the chip of the microcomputer 12 as input/output terminals. (not shown).

A comparator or the like including an active element is used in the communication circuit 16 (not shown). Power of voltage +B is supplied to operate. Various configurations including active elements can be applied to the communication circuit 16 .

One ends of an input line 22A and an output line 22B formed by wiring patterns on the substrate 14 are connected to the communication circuit 16 . The other ends of the input line 22A and the output line 22B are pin 20A serving as an input terminal (IN terminal) for a communication signal (reception signal Sin) in the microcomputer 12, and output of a communication signal (transmission signal Sout) in the microcomputer 12. It is connected to pin 20B as a terminal (OUT terminal). The communication circuit 16 outputs the communication signal S input via the communication line 18 as the reception signal Sin to the pin 20A of the microcomputer 12, and the transmission signal Sout output from the pin 20B of the microcomputer 12 as the communication signal S to the communication line. Output to 18.

On the other hand, an activation control device 24 is formed in the ECU 10, and the activation control device 24 includes an activation control section 26 and a signal detection circuit 28 as a detection circuit. The signal detection circuit 28 detects a communication signal S input/output via the communication line 18 and makes it possible to determine whether or not communication is being performed. In addition, the activation control unit 26 controls the activation/stopping (operation/operation stoppage) of the communication circuit 16 by connecting/disconnecting the communication circuit 16 and the power supply. At this time, in the activation control device 24 , the activation control section 26 operates the communication circuit 16 based on the output signal D of the signal detection circuit 28 .

The activation control unit 26 includes a pnp-type transistor (bipolar transistor) 30 as a switching element, a latch circuit 32, a release circuit 34, and an npn-type transistor . The transistor 30 has an emitter E connected to the power supply (+B) side, a collector C connected to the communication circuit 16 , and a base B connected to the output side of the latch circuit 32 .

When a set signal (latch signal) Rs that changes from H level to L level, for example, is input to the latch circuit 32, the output signal Q changes from H level to L level and is held at L level (latch, latch set). Also, the output signal Q of the latch circuit 32 changes from L level to H level (latch release, latch reset) by inputting a reset signal (latch release signal) Rr that changes from H level to L level.

In the start control unit 26, in the latched state where the output signal Q of the latch circuit 32 is at L level, the potential of the base B of the transistor 30 is lowered, and the current is conducted between the emitter E and the collector C of the transistor 30. (on). The communication circuit 16 is connected to the power supply and activated by energization between the emitter E and the collector C of the transistor 30 .

The input side (set signal Rs side) of the latch circuit 32 is connected to the collector C of the transistor 36, and a required voltage can be applied to the collector C thereof. The transistor 36 has an emitter E grounded (GND) and a base B connected to a pin 20C serving as an output terminal (OUT terminal) of the microcomputer 12 .

The release circuit 34 has an output side connected to the input side (reset signal Rr side) of the latch circuit 32 and an input side connected to the pin 20D serving as the output terminal (OUT terminal) of the microcomputer 12 .

In the microcomputer 12, the pin 20C is used for outputting the activation signal Ss of the communication circuit 16, and when the microcomputer 12 performs communication using the communication circuit 16, the pin 20C changes from L level to H level. In the activation control unit 26, the pin 20C (base B of the transistor 36) of the microcomputer 12 becomes H level, the transistor 36 is turned on, the collector C becomes L level, and the set signal Rs is input to the latch circuit 32. be.

In the microcomputer 12, the pin 20D is used for outputting a stop signal (activation stop signal) Sr for the communication circuit 16, and the microcomputer 12 changes the pin 20D from the L level to the H level after completing the communication. It outputs the signal Sr. In the activation control unit 26 , when the stop signal Sr is output from the pin 20D of the microcomputer 12 , the release circuit 34 outputs to the latch circuit 32 the reset signal Rr that changes from H level to L level. Accordingly, the microcomputer 12 can activate/deactivate the communication circuit 16 by turning on/off the transistor 30 of the activation control section 26 with the activation signal Ss and the termination signal Sr.

On the other hand, the signal detection circuit 28 uses a pnp transistor 38 and an npn transistor 40 . The transistor 38 has an emitter E connected to a power source (+B), a collector C grounded via a required passive element, and a base B connected to the communication line 18 . The transistor 40 has an emitter E grounded, a collector C capable of applying a required voltage, and a base B connected to the collector C of the transistor 38 .

As a result, in the signal detection circuit 28, when the communication signal S on the communication line 18 changes from H level to L level, the emitter E and the collector C of the transistor 38 are energized (the transistor 38 is turned on), and the collector C changes from L level to H level. In the signal detection circuit 28, the collector C of the transistor 38 (the base B of the transistor 40) becomes H level, so that the collector C of the transistor 40 changes from H level to L level (the transistor 40 is turned on).

In the signal detection circuit 28, the collector C of the transistor 40 serving as the output terminal of the output signal D is connected to the pin 20E serving as the input terminal of the microcomputer 12, and the collector C of the transistor 36 of the activation control unit 26 (the output terminal of the set signal Rs of the latch circuit 32). input side). A pin 20E of the microcomputer 12 is an input (INT: Interrupt) terminal for communication of the microcomputer 12 .

In the activation control unit 26, when the collector C of the transistor 40 of the signal detection circuit 28 becomes L level, the set signal Rs is input to the latch circuit 32, and the latch circuit 32 enters the latch state. Accordingly, in the activation control device 24 , the communication circuit 16 is activated when the communication signal S is detected by the signal detection circuit 28 . Further, in the microcomputer 12, when the collector C of the transistor 40 of the signal detection circuit 28 becomes L level, the microcomputer 12 is activated if it is in the sleep state.

Next, the operation of the ECU 10 will be explained.
In the ECU 10 , the activation control device 24 activates the communication circuit 16 so that the microcomputer 12 can communicate with other ECUs using the communication circuit 16 . Further, in the ECU 10 , the start control device 24 stops the communication circuit 16 in response to the stop signal Sr from the microcomputer 12 . Note that the activation control device 24 can activate the communication circuit 16 by the activation signal Ss output from the pin 20C of the microcomputer 12 .

2(A) to 2(G) show schematic diagrams of signal changes in the activation control device 24. FIG. 2A shows the communication signal S (signal on the communication line 18), and FIG. 2B shows the output signal D (set signal Rs) of the signal detection circuit 28. 2(C) shows the output signal Q of the latch circuit 32, and FIG. 2(D) shows the voltage supplied to the communication circuit 16. As shown in FIG. 2(E) shows the stop signal Sr, FIG. 2(F) shows the reception signal Sin input to the microcomputer 12, and FIG. Signal Sout is shown.

In the ECU 10, when the microcomputer 12 is in a sleep state and communication with other ECUs is stopped, the output signal Q of the latch circuit 32 of the activation control device 24 becomes H level. (unlatched state). As a result, in the activation control device 24, the transistor 30 is turned off, the connection between the communication circuit 16 and the power supply is cut off, and the power supply to the communication circuit 16 is stopped. In the ECU 10, the power consumption in the communication circuit 16 is suppressed by cutting off the power supply to the communication circuit 16. FIG.

Here, when another ECU or the like starts communication with the ECU 10, the communication signal S input to the ECU 10 via the communication line 18 changes from H level to L level (see FIG. 2A). As a result, in the activation control device 24, the transistors 38 and 40 of the signal detection circuit 28 are turned on in turn, and the output signal D of the signal detection circuit 28 changes from H level to L level (see FIG. 2B).

In the activation control device 24, the output signal D of the signal detection circuit 28 is input to the latch circuit 32 of the activation control section 26 as the set signal Rs. In the latch circuit 32, when the output signal D (set signal Rs) changes from H level to L level, the output signal Q changes from H level to L level, and the output signal Q is held at L level (FIG. 2(C)).

In the activation control unit 26, the transistor 30 operates according to the output signal Q of the latch circuit 32, and the transistor 30 is turned on when the output signal Q becomes L level. As a result, in the ECU 10, the power supply and the communication circuit 16 are connected, the voltage +B is supplied, and the communication circuit 16 is activated (see FIG. 2(D)).

In the ECU 10, the output signal D of the signal detection circuit 28 is input to the pin 20E (INT terminal) of the microcomputer 12 as an INT signal. In the microcomputer 12, when the pin 20E changes from the H level to the L level in the sleep state or the like, the sleep is released. As a result, the ECU 10 starts communication between the microcomputer 12 and the microcomputers of other ECUs.

When activated, the communication circuit 16 outputs the received signal Sin to the pin 20A of the microcomputer 12 according to the communication signal S input via the communication line 18 (see FIGS. 2A and 2F). )reference). Also, the communication circuit 16 outputs the transmission signal Sout input from the pin 20B of the microcomputer 12 as the communication signal S through the communication line 18 (see FIGS. 2A and 2G).

On the other hand, when starting communication, the microcomputer 12 sets the pin 20D for outputting the stop signal Sr of the communication circuit 16 to L level. Further, the microcomputer 12 changes the pin 20D (stop signal Sr) from the L level to the H level (see FIG. 2(E)) when terminating communication with another ECU or the like.

The release circuit 34 of the activation control unit 26 outputs the reset signal Rr when the stop signal Sr input from the microcomputer 12 changes from L level to H level. When the reset signal Rr is input, the latch circuit 32 is unlatched and changes the output signal Q from L level to H level (see FIG. 2(C)). As a result, in the ECU 10, the transistor 30 of the activation control unit 26 is turned off, power supply to the communication circuit 16 is stopped, and the communication circuit 16 stops operating.

As described above, the ECU 10 includes the activation control device 24 together with the microcomputer 12 and the communication circuit 16 , and the activation control device 24 activates the communication circuit 16 . Further, in the activation control device 24, the latch circuit 32 is latched by the output signal D of the signal detection circuit 28 for detecting the communication signal S, and the transistor 30 connecting the communication circuit 16 and the power supply is turned on. As a result, when the communication signal S is detected, the activation controller 24 can activate the communication circuit 16 without delay. Save time. Moreover, since the activation control device 24 outputs the output signal D of the signal detection circuit 28 to the pin 20E of the microcomputer 12, the microcomputer 12 can be activated in parallel with the communication circuit 16, and other ECUs can be activated without delay. communication can be initiated between

Further, the activation control device 24 has a simple configuration in which the latch circuit 32 turns on/off the transistor 30 by turning on/off the transistors 38 and 40 of the signal detection circuit 28 . Moreover, in the activation control device 24, the transistors 30, 38, and 40 are turned off when the communication circuit 16 is stopped, so power consumption when the communication circuit 16 is stopped can be suppressed more effectively.

In the start control device 24, the microcomputer 12 was started by inputting the output signal D of the signal detection circuit 28 to the pin 20E (INT terminal) of the microcomputer 12. FIG. However, if the microcomputer 12 can be activated by a signal input to the pin 20A (IN terminal), the output signal D may be input to the pin 20A, thereby reducing the number of pins 20 of the microcomputer 12. FIG.

[Second embodiment]
Next, a second embodiment will be described. In the second embodiment, functional components similar to those in the first embodiment are given the same reference numerals as those in the first embodiment, and detailed description thereof will be omitted.

An ECU 50 as an electronic control unit is applied to the second embodiment, and the ECU 50 is used in place of the ECU 10 of the first embodiment. FIG. 3 shows a schematic configuration of the ECU 50 in a block diagram.

As shown in FIG. 3, the ECU 50 is provided with a communication circuit 16, a microcomputer 52, and an activation control device 54. The microcomputer 52 and the activation control device 54 correspond to the microcomputer 12 and the activation control device 24 of the first embodiment, respectively. is applied instead. Activation control device 54 includes signal detection circuit 28 and activation control unit 56. Activation control unit 54 includes transistor 30, latch circuit 32, latch release circuit 58, and determination circuit as a continuation determination circuit. 60 is different from the activation control device 24 of the first embodiment.

In the activation control device 54 of the ECU 50 , the activation control unit 56 activates and deactivates the communication circuit 16 based on the output signal D of the signal detection circuit 28 .

A pin 20B and a pin 20F are formed in the microcomputer 52 of the ECU 50, and the pin 20F is used instead of the pins 20A and 20E of the microcomputer 12. The communication circuit 16 is connected to a pin 20F of the microcomputer 52 via an input line 22A, and connected to a pin 20B of the microcomputer 52 via an output line 22B.

A pin 20F of the microcomputer 52 is connected to the output terminal of the signal detection circuit 28 (the collector C side of the transistor 40). In the microcomputer 52, a pin 20F (IN/INT terminal) is used as an input terminal (IN terminal) for the received signal Sin and an input terminal (INT terminal) for the INT signal. and the output signal D of the signal detection circuit 28 are input. In the sleep state, the microcomputer 52 receives a signal that changes from H level to L level, for example, to the pin 20F in the sleep state. A signal is received as received signal Sin.

In the activation control unit 56 of the activation control device 54, the output end of the signal detection circuit 28 is connected to the input side (set signal Rs side) of the latch circuit 32, and the latch circuit 32 receives the signal detection circuit 28 as the set signal Rs. is applied. As a result, in the latch circuit 32, the output signal D changes from H level to L level, so that the output signal Q changes from H level to L level and is held.

The output terminal (collector C of the transistor 40) of the signal detection circuit 28 is connected to the input side of the determination circuit 60 of the activation control unit 56, and the output signal D of the signal detection circuit 28 is supplied to the determination circuit 60. is entered. The output side of the determination circuit 60 is connected to the input side of the latch release circuit 58 , and the output side of the latch release circuit 58 is connected to the input side (reset signal Rr side) of the latch circuit 32 . The determination circuit 60 outputs a determination signal Sh corresponding to the output signal D of the signal detection circuit 28, and the latch release circuit 58 outputs a reset signal Rr based on the determination signal Sh.

The determination circuit 60 determines from the output signal D whether or not a series of reception signals Sin or transmission signals Sout has been detected, and outputs a determination signal Sh. Further, the latch canceling circuit 58 sends a reset signal Rr to the latch circuit 32 after the elapse of the time at which it is determined that the communication between the microcomputer 12 and the microcomputers of the other ECUs has ended based on the determination signal Sh. Output.

In general, the communication signal S (the transmission signal Sout and the reception signal Sin) changes in a pulse shape, and the maximum pulse interval in the series of the reception signal Sin and the transmission signal Sout in the communication signal S is a preset time Tc It is said to be within In a series of two-way communications, the time interval (interval between transmission and reception) between the pulse of the transmission signal Sout and the pulse of the reception signal Sin is within the preset time Td. The output signal D of the signal detection circuit 28 has a pulse interval similar to the pulse interval of each pulse in the communication signal S. The output signal D is a pulse signal that changes from H level to L level. level to L level).

Here, time Ta and time Tb are set as delay times in the determination circuit 60 and the latch release circuit 58, respectively. The time Ta in the determination circuit 60 is set to be longer than the time Tc and shorter than the time Td (Tc<Ta<Td). The time Tb in the latch release circuit 58 is set so that the predetermined time Ts (Ts=Ta+Tb) added to the time Ta is longer than the time Td (Ts>Td).

In the determination circuit 60, when the next pulse (rising edge) is detected within the time Ta after the trailing edge of the previous pulse is detected in the output signal D, a series of received signal Sin or transmitted signal Sout is detected. is not completed, and the determination signal Sh is held at L level. Further, in the determination circuit 60, when the next pulse is not detected within the time Ta after the falling edge of the previous pulse is detected in the output signal D, the series of reception signal Sin or transmission signal Sout is output. It is determined that the processing has ended, and the determination signal Sh is changed from the L level to the H level.

Such a determination circuit 60 can be applied to an F/V (frequency/voltage) conversion circuit, a timer circuit, or the like, the output of which changes according to the interval of input pulse signals. The F/V conversion circuit and timer circuit used in the determination circuit 60, for example, when the time interval of the pulse signals in the output signal D reaches (exceeds) the time Ta, outputs a signal of H level, and the time interval of the pulse signals is A configuration in which an L level signal is output when the time is equal to or less than the time Ta can be applied.

The latch release circuit 58 has the same configuration as the release circuit 34 plus a delay circuit. , outputs a reset signal Rr that changes from H level to L level.

Next, the operation of the ECU 50 will be explained.
In the ECU 50, the activation control device 54 activates the communication circuit 16 based on the communication signal S input via the communication line 18, and when it is determined that the communication signal S is stopped and the communication is terminated, the communication circuit 16 is activated. to stop starting.

4A to 4H schematically show signal changes in the activation control device 54. FIG. 4A shows the communication signal S, FIG. 4B shows the output signal D (set signal Rs) of the signal detection circuit 28, and FIG. The output signal Q of the latch circuit 32 is shown, and the voltage supplied to the communication circuit 16 is shown in FIG. 4(D). 4(E) shows the judgment signal Sh of the judgment circuit 60, and FIG. 4(F) shows the reset signal Rr of the latch release circuit 58. As shown in FIG. Further, FIG. 4G shows the reception signal Sin input to the microcomputer 52, and FIG. 4H shows the transmission signal Sout of the microcomputer 52. As shown in FIG.

In the ECU 50, when the microcomputer 52 is in a sleep state and communication with other ECUs is stopped, the output signal Q of the latch circuit 32 of the activation control device 54 becomes H level. (unlatched state). As a result, in the ECU 50, the power supply to the communication circuit 16 is cut off and the operation of the communication circuit 16 is stopped.

Here, in the communication circuit 16, when a communication signal S (see FIG. 4A) for communication is input from another ECU (microcomputer of) or the like via the communication line 18, the base B of the transistor 38 is It changes from H level to L level. As a result, in the signal detection circuit 28, the transistors 38 and 40 are sequentially turned on, and the collector C (output signal D) of the transistor 40 changes from H level to L level (see FIG. 4B).

In the activation control device 54, the output signal D of the signal detection circuit 28 is input to the latch circuit 32 as the set signal Rs. In the latch circuit 32, when the set signal Rs (output signal D) changing from the H level to the L level is input, the output signal Q changes from the H level to the L level and the output signal Q is held at the L level. (See FIG. 4(C)).

In the activation control device 54, the transistor 30 operates according to the output signal Q of the latch circuit 32, and the transistor 30 is turned on when the output signal Q becomes L level. As a result, in the ECU 50, the power supply and the communication circuit 16 are connected to supply the voltage +B, and the communication circuit 16 is activated (see FIG. 4(D)).

Further, in the ECU 50, the output signal D of the signal detection circuit 28 is input to the pin 20F (IN/INT terminal) of the microcomputer 52. FIG. In the microcomputer 12, when the output signal D changes the pin 20F from H level to L level in the sleep state or the like, the sleep state is canceled and the communication program or the like is activated. As a result, in the ECU 50, the microcomputer 52 and the communication circuit 16 are activated in parallel, and the microcomputer 52 starts communication with the microcomputers of other ECUs.

In the ECU 50, when the communication circuit 16 is activated, the reception signal Sin corresponding to the communication signal S input via the communication line 18 is input from the communication circuit 16 to the pin 20F of the microcomputer 52 (FIG. 4 (A ) and FIG. 4(G)). In the ECU 50, the communication circuit 16 outputs the transmission signal Sout output from the pin 20B of the microcomputer 12 as the communication signal S through the communication line 18 (see FIGS. 4A and 4H).

In the activation control device 54 , the output signal D of the signal detection circuit 28 is a signal that changes in phase with the reception signal Sin output from the communication circuit 16 . In the activation control device 54 , the output signal of the signal detection circuit 28 is superimposed on the input line 22A connecting the communication circuit 16 and the pin 20F of the microcomputer 52 . Therefore, the output signal D, which changes in the same phase as the received signal Sin, is input to the pin 20F of the microcomputer 52 before the communication circuit 16 operates. can also receive the reception signal Sin corresponding to the communication signal S.

On the other hand, in the activation control device 54 , the output signal D of the signal detection circuit 28 is input to the determination circuit 60 . When the signal detection circuit 28 detects the communication signal S and the output signal D changes from H level to L level, the decision circuit 60 changes the decision signal Sh from H level to L level. Further, the determination circuit 60 changes the determination signal Sh from the L level to the H level when the time Ta has elapsed since the series of received signal Sin or the transmitted signal Sout ended and the pulse in the output signal D was interrupted. The latch release circuit 58 outputs a reset signal Rr when the decision signal Sh changes from L level to H level and remains at H level for a predetermined time Tb.

Here, the time Ta is set longer than the time Td between the received signal Sin and the transmitted signal Sout (or between the transmitted signal Sout and the received signal Sin). A time Ts (Ts=Ta+Tb) obtained by summing the time Ta in the determination circuit 60 and the time (delay time) Tb in the latch release circuit 58 is longer than the time Td (Ts>Td).

Therefore, in the determination circuit 60, for example, when the transmission signal Sout is output after the reception signal Sin is stopped, the determination signal Sh is returned from the H level to the L level (FIGS. 4A, 4B, and 4C). See FIG. 4(E)). Accordingly, when the transmission signal Sout is output from the microcomputer 52 after the reception signal Sin is stopped, the latch release circuit 58 holds the reset signal Rr at H level (reset signal Rr is not output. FIG. 4 (E ) and FIG. 4(F)).

On the other hand, in the activation control device 54, after a series of communications is completed and the determination signal Sh of the determination circuit 60 becomes H level, the latch release circuit 58 outputs the reset signal Rr when the time Tb elapses. do. That is, in the activation control device 54, when a time Ts (Ts=Ta+Tb) longer than the time Td has elapsed since the last pulse signal was detected, the latch circuit 32 is unlatched and the transistor 30 is turned off. As a result, the ECU 50 stops power supply to the communication circuit 16 and the communication circuit 16 is stopped.

As described above, the ECU 50 includes the communication circuit 16 and the activation control device 54 together with the microcomputer 52 , and the activation control device 54 activates the communication circuit 16 . The activation control device 54 outputs an output signal D when the signal detection circuit 28 detects a signal (communication signal S) input via the communication line 18 . Further, in the activation control unit 56, the latch circuit 32 is latched by the output signal D of the signal detection circuit 28 to turn on the transistor 30 connecting the communication circuit 16 and the power supply.

As a result, when the communication signal S is detected, the activation control device 54 of the ECU 50 connects the power source and the communication circuit 16 without delay and activates the communication circuit 16. 52, the activation time of the communication circuit 16 can be shortened. Moreover, since the activation control device 54 outputs the output signal D of the signal detection circuit 28 to the pin 20F of the microcomputer 52, even if the microcomputer 52 is in a sleep state, the microcomputer 52 can be activated in parallel with the communication circuit 16. communication with other ECUs can be started without delay.

In addition, the start control device 54 has a simple configuration for starting the communication circuit 16 by using the latch circuit 32 and turning on/off the transistor 30 by turning on/off the transistors 38 and 40 of the signal detection circuit 28 . Moreover, in the activation control device 54, the transistors 30, 38, and 40 are turned off when the communication circuit 16 is stopped, so power consumption when the communication circuit 16 is stopped can be suppressed more effectively.

Furthermore, the activation control device 54 has a simple configuration in which the transistor 30 is turned on/off by turning on/off the transistors 38 and 40 of the signal detection circuit 28 using the latch circuit 32 . Moreover, in the activation control device 54, the transistors 30, 38, and 40 are turned off when the communication circuit 16 is stopped, so power consumption when the communication circuit 16 is stopped can be suppressed more effectively.

Therefore, the activation control device 54 of the ECU 50 has the same effect as the activation control device 24 of the ECU 10 of the first embodiment in activating the communication circuit 16 .

On the other hand, the determination circuit 60 of the activation control device 54 outputs a determination signal Sh corresponding to the time interval of the pulses in the output signal D. FIG. The determination signal Sh changes from the L level to the H level when the time Ta elapses between the detection of the previous pulse and the detection of the next pulse. Further, the latch release circuit 58 outputs a reset signal Rr to the latch circuit 32 if the judgment signal Sh does not change to L level within the time Tb after it changes to H level. As a result, when the time Ts (Ts=Ta+Tb) elapses between the detection of the previous pulse and the detection of the next pulse, the start control device 54 unlatches the latch circuit 32 and the transistor 30 is turned on. It is turned off and power supply to the communication circuit 16 is stopped.

Further, in the activation control device 54, the time Ta in the determination circuit 60 is made longer than the time Tc in the communication signal S (the received signal Sin and the transmitted signal Sout) (Ta>Tc). As a result, it is possible to effectively determine from the output signal D of the signal detection circuit 28 that the communication between the microcomputer and the external device has ended with a simple configuration using hardware. Moreover, the decision circuit 60 can suppress the change of the decision signal Sh during the reception of the reception signal Sin and the transmission of the transmission signal Sout.

Further, in the ECU 50 , the activation control device 54 activates and stops the communication circuit 16 without going through the microcomputer 52 . Therefore, the microcomputer 52 does not require the pin 20 for outputting the start/stop signal of the communication circuit 16, and the microcomputer 52 can reduce the number of pins that affect the chip size. Further, in the microcomputer 52 of the ECU 50, the pin 20F is used for the input of the output signal D and the input of the received signal Sin, so the number of pins in the microcomputer 52 is further reduced.

Accordingly, in the ECU 50, the microcomputer 52 can be made smaller. Also, in the microcomputer 52, since pins for communication are reduced through the communication circuit 16, if the size (number of pins) is the same, it can be used for input/output of other signals. can be added.

In the microcomputer 52 of the ECU 50, the output signal D of the signal detection circuit 28 and the reception signal Sin output from the communication circuit 16 are input to the pin 20F. In the activation control device 54, the output signal D is a signal that changes in the same manner as the received signal Sin. Therefore, since a signal similar to the received signal Sin is input to the microcomputer 52 prior to starting the communication circuit 16, the communication signal S can be received from the beginning.

In the activation control device 54, the time Ts is the total time of the time Ta in the determination circuit 60 and the time Tb in the latch release circuit 58 by providing the latch release circuit 58 with a delay function. However, the time Ta of the determination circuit 60 may be set to be the time Ts (Ta=Ts), thereby eliminating the need for the delay function in the latch release circuit 58 and simplifying the configuration of the latch release circuit 58. . Further, the function of the determination circuit 60 may be provided to the latch release circuit 58 so that the time Tb of the latch release circuit 58 becomes the time Ts (Tb=Ts). As a result, the determination circuit 60 can be omitted from the activation control device 54 .

In the above-described first and second embodiments, the activation control devices 24 and 54 using bipolar transistors as the transistors 30 and the like are described as examples. However, the activation control device may use a field effect transistor (FET) as an active element such as a switching element.

Further, in the first and second embodiments, the signal detection circuit 28 formed by the transistors 38 and 40 detects the fall of the communication signal S. FIG. However, the sensing circuit may sense the rising edge of the signal being communicated, and the sensing circuit may employ various configurations for sensing the rising edge or falling edge of the signal.

10, 50... ECU (Electronic Control Unit) 12, 52... Microcomputer 24, 54... Activation control device 26, 56... Activation control section 28... Signal detection circuit (detection circuit), 30...transistor (switching element), 32...latch circuit, 58...latch release circuit, 60...decision circuit (continuation decision circuit).

Claims (6)

It is provided in the electronic control device together with the microcomputer and operates when power is supplied, and enables signal transmission and reception between the external device connected to the electronic control device by a signal line and the microcomputer. a communication circuit;
a switching element that is operated to enable the power to be supplied to the communication circuit;
a detection circuit that detects a change in a signal for communication on the signal line and outputs a detection signal according to the detected signal change;
a latch circuit that receives a latch signal to operate the switching element to enable power supply to the communication circuit and receives the detection signal as the latch signal;
starting control device including; 2. The activation control device according to claim 1, wherein said latch circuit is unlatched by a release signal output from said microcomputer to stop said switching element from supplying power to said communication circuit. The latch circuit can output a latch release signal for de-energizing the switching element to the communication circuit, and the non-change state of the signal in the detection signal enables communication between the microcomputer and the external device. 2. The activation control device according to claim 1, further comprising an unlatch circuit for outputting said unlatch signal upon reaching a time at which it is determined that the activation has ended. A continuation determination circuit that outputs a determination signal indicating whether or not a series of signal receptions or signal transmissions is detected by the detection circuit based on the change state of the signal in the detection signal,
4. The activation control device according to claim 3, wherein the latch release circuit outputs the latch release signal based on the elapsed time after it is determined from the determination signal that the series of signal receptions or signal transmissions has ended. 5. The activation control device according to claim 1, wherein the detection signal from the detection circuit is output to the microcomputer as an activation signal. 6. The activation control according to claim 5, wherein said microcomputer includes an input terminal for inputting a reception signal and an output terminal for outputting a transmission signal, and said detection signal of said detection circuit is input to said input terminal. Device.

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