JP2009248938A - On-vehicle electronic control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out detection of communication abnormality with good accuracy and with less time lag in communication between ICs of an on-vehicle electronic control apparatus. <P>SOLUTION: The on-vehicle electronic control apparatus 10 is provided with: a transmission side IC 20 having a communication interface for receiving an on/of detection signal of a switch of an on-vehicle device; a receive side IC 30 for receiving the on/off detection signal; and abnormality checking function for the on/off detection signal which the receive side IC receives. The transmission side IC 20 is provided with: an input latch part 21 having a bit assigned per a receiving switch; a register part 22; a comparison part 23 which is connected with a branched wire branched from wiring connecting the register part with the receive side IC and is connected with the input latch part; and a switching part 24 which is connected with each bit in the input latch part and inputs the on/off signal to the comparison part. In the comparison part, the on/of signal output to a wiring side is compared with the on/off signal output per bit from the input latch part, and a non-matching bit is determined to be an error bit. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an on-vehicle electronic control device, and more specifically, detects communication abnormality of an on / off detection signal of a switch of an on-vehicle device within the electronic control device.

Conventionally, electrical components such as lights and power windows mounted on vehicles are controlled by an electronic control unit.
Specifically, the electronic control device includes a transmission-side IC and a reception-side IC. When the occupant performs a switch operation, an on / off detection signal of the switch is input to the transmission-side IC of the electronic control device. Further, the on / off detection signal is input from the transmission side IC to the reception side IC, and when the reception side IC determines that the switch is on, the electronic control device controls the electrical component.

  However, since many electrical components are mounted on the vehicle, noise from other electrical components may be mixed into the electronic control device. At this time, when an on / off detection signal is input from the transmission side IC to the reception side IC in the electronic control unit, the on / off detection signal becomes abnormal due to the influence of noise, and the reception side IC cannot correctly detect the on / off of the switch. There is.

For this reason, in Japanese Patent Application Laid-Open No. 7-269409 (Patent Document 1), in serial communication between two CPUs, the CPU on the transmission side adds the SUM value of all data to the data and transmits it to the CPU on the reception side. A configuration is disclosed in which the SUM value of data is calculated again by the receiving CPU, and the data is checked for abnormality by comparing with the received SUM value. If the comparison result is correct, the data is treated as not abnormal.
In addition, as a data abnormality check method, data input to one IC is returned to the other IC, and compared with the data transmitted last time by the other IC, echo back for detecting data communication abnormality, There are also methods such as adding parity bits to.

  However, the echo back has a problem that abnormality determination is delayed by one cycle of communication. Further, the method of adding a parity bit has a problem that communication abnormality cannot be detected depending on how noise is introduced.

JP-A-7-269409

  The present invention has been made in view of the above problems, and an object of the present invention is to perform communication abnormality detection with a small time lag and high accuracy in data communication between ICs of an on-vehicle electronic control device.

In order to solve the above problems, the present invention provides a transmission side IC having a communication interface that receives an on / off detection signal of a switch of an in-vehicle device, and a reception side that receives the on / off detection signal from the transmission side IC via a wiring. An on-vehicle electronic control device having an on-off detection signal abnormality check function received by the receiving side IC,
The communication interface of the transmission side IC includes an input latch unit having a bit assigned for each on / off detection signal of a switch to be received, a bit for receiving an on / off detection signal from the input latch unit and each bit, and the received on / off A register unit that sequentially transmits a detection signal to the reception-side IC through the wiring via serial communication;
Furthermore, the transmitting side IC
A comparison unit connected to the branch line branched from the wiring connecting the register unit and the receiving side IC and connected to the input latch unit;
A switching unit that connects to each bit of the input latch unit, and switches the on / off detection signal output from the input latch unit for each switch and inputs the switch to the comparison unit;
The comparison unit compares the on / off detection signal output to the wiring side with the on / off detection signal output for each bit from the input latch unit, and determines that the bit does not match as an error bit. An in-vehicle electronic control device is provided.

According to the above configuration, in order to detect whether or not a communication abnormality has occurred due to noise mixing when transmitting a switch on / off detection signal from the transmission side IC, which is a communication interface, to the reception side IC, The on / off detection signal transmitted from the IC to the receiving side IC is compared with the on / off detection signal input from the switch to the input latch portion of the communication interface. If these on / off detection signals do not match, it is determined that an abnormality has occurred in the on / off detection signal of the switch.
In this way, the on / off detection signal transmitted from the transmission side IC to the reception side IC is compared with the on / off detection signal stored in the input latch unit that is directly input from the switch and is least likely to be mixed with noise. Thus, it is possible to accurately detect the communication abnormality of the on / off detection signal transmitted from the transmission side IC to the reception side IC.

  In addition, since the communication interface register unit performs communication abnormality determination at the timing when the on / off detection signal is transmitted to the reception-side IC, it is possible to prevent occurrence of a time lag such as a communication abnormality determination being delayed by one cycle.

  The input latch unit includes an error bit for storing a determination result output from the comparison unit, and transmits the determination result of the error bit to the register unit, and the register unit transmits the determination result to the microcomputer. It is preferable.

  According to the above configuration, the microcomputer performs error processing such as a retransmission request when there is a communication abnormality in order to obtain a communication abnormality determination result of the switch on / off detection signal transmitted from the transmission side IC to the reception side IC. be able to.

It is preferable that a holding unit for holding an abnormality determination result is provided between error bits of the comparison unit and the input latch unit.
When a plurality of switches are connected, the register unit of the transmission side IC sequentially transmits on / off detection signals of all the connected switches to the reception side IC. At this time, if any one of the plurality of on / off detection signals has a communication abnormality, the holding unit holds the determination result of the communication abnormality and determines that a communication abnormality has occurred.

  The transmission side IC and the reception side IC are mounted on the same printed circuit board accommodated in the same housing, and the conductor on the printed circuit board is a wiring having a branch line connected to the comparison unit, or on a separate printed circuit board It is preferable that the wiring on the printed circuit board and the jumper wire connecting between the conductors have a branch line connected to the comparison portion.

  The transmission side IC and the reception side IC are mounted on a printed circuit board housed in a separate housing, and have a branch line in which a conductor on the printed circuit board and a wire connecting the conductors are connected to the comparison unit It may be.

The switch connected to the communication interface of the transmitting side IC is at least one of a door lock switch, an unlock switch, a headlight switch, a sunroof switch, a wiper switch, and an air conditioner switch, and is operated by a passenger.
This is because an electronic control device to which these switches are connected is often housed in a resin case without a shield, and noise is likely to be mixed into the conductive wire, so that it is necessary to determine a communication abnormality.

As described above, according to the on-vehicle electronic control device of the present invention, the on / off detection signal transmitted from the transmission side IC to the reception side IC is directly input from the switch, and the possibility that noise is mixed is the least. By comparing with the on / off detection signal stored in the input latch unit, it is possible to accurately detect the communication abnormality of the on / off detection signal transmitted from the transmission side IC to the reception side IC.
In addition, since the communication interface register unit performs communication abnormality determination at the timing when the on / off detection signal is transmitted to the reception-side IC, it is possible to prevent occurrence of a time lag such as a communication abnormality determination being delayed by one cycle.

1 and 2 show a first embodiment of the present invention.
As shown in FIG. 1, an on-vehicle electronic control unit (ECU) 10 of the present invention includes a communication interface 20 that constitutes a transmission-side IC that receives an on / off detection signal of a switch 11 of an on-vehicle device, and the transmission-side IC. And a microcomputer 30 constituting a receiving side IC that receives an on / off detection signal via a wiring.

The communication interface 20 and the microcomputer 30 are mounted on the same printed circuit board 12 accommodated in the same housing, and are connected by a conductor 13 on the printed circuit board 12, and the switch 11 received by the communication interface 20 through the conductor 13. An on / off detection signal is transmitted to the microcomputer 30. Further, the branch line 14 extends from the branch point of the conductor 13 on the printed circuit board 12, and the branch line 14 is connected to the communication interface 20 again. The branch point is located as close as possible to the microcomputer 30.
The ECU 10 checks a communication abnormality caused by noise entering from the conductor 13.

The communication interface 20 includes an input latch unit 21, a register unit 22, a comparison unit 23, a switching unit 24, and a holding unit 25.
Each bit of the input latch unit 21 is assigned for each on / off detection signal of the switch 11 to be received. In addition, the final bit is the error bit 21a, and the determination result output from the comparison unit 23 is stored. In this embodiment, the input latch unit 21 has 24 bits, and the 1st to 23rd bits are connected to each switch 11 to receive an on / off detection signal, and the 24th bit is used as an error bit 21a.

The register unit 22 includes a bit that receives an on / off detection signal from each bit of the input latch unit 21, and is a shift register that sequentially transmits the received on / off detection signal to the microcomputer 30 via the conductor 13 through serial communication.
The comparison unit 23 is an on / off detection signal (referred to as a first on / off detection signal S1) output to each bit from the input latch unit 21 and an on / off detection signal transmitted from the register unit 22 to the microcomputer 30. And an on / off detection signal (referred to as a second on / off detection signal S2) input via a branch line 14 branched from a wiring connecting the microcomputer 30 and the microcomputer 30 as an input signal. When the first on / off detection signal S1 and the second on / off detection signal S2 match, the communication is normal, and when the first on / off detection signal S1 and the second on / off detection signal S2 are different, it is determined that the communication is abnormal. The abnormality determination result is output to the error bit 21a via the holding unit 25.

The switching unit 24 is connected to each bit of the input latch unit 21 and is also connected to the comparison unit 23. The on / off detection signal output from the input latch unit 21 is switched for each switch 11 and input to the comparison unit 23. Yes.
The holding unit 25 is interposed between the comparison unit 23 and the error bit 21a of the input latch unit 21, holds the abnormality determination result from the comparison unit 23, and inputs it to the error bit 21a. The holding unit 25 is configured by, for example, a D? F / F circuit (flip-flop circuit).

The on-vehicle equipment switch 11 connected to the input latch portion 21 of the communication interface 20 is, for example, a door lock switch, an unlock switch, a headlight switch, a sunroof switch, a wiper switch, or an air conditioner switch, which is operated by a passenger. is there.
The switch 11 is connected to a battery and a resistor, and an on / off detection signal of the switch 11 is generated by the battery and the resistor and input to the input latch portion 21 of the communication interface 20.

The microcomputer 30 is connected to the FET 15, and the microcomputer 30 transmits a sampling signal to the FET 15. While the sampling signal is input to the FET 15, an on / off detection signal is generated by the on / off of the switch 11.
The microcomputer 30 transmits a communication permission signal to the communication interface 20, and the communication of the on / off detection signal between the microcomputer 30 and the communication interface 20 is started by transmitting the signal to the communication interface 20.
Further, the microcomputer 30 transmits a communication clock signal to the communication interface 20. The register unit 22 outputs an on / off detection signal to the microcomputer 30 based on the timing when the communication clock signal becomes “1” or “0”.

Next, operation | movement of ECU10 of this invention is demonstrated using the example of the timing chart of FIG.
First, at timing 1, the microcomputer 30 transmits a sampling signal to the battery, and an on / off detection signal is generated when the switch 11 is turned on / off. At this time, an ON / OFF detection signal of the switch 11 is input from the switch 11 side to each bit of the input latch unit 21 and is sent to the register unit 22.
At timing 2, the microcomputer 30 transmits a communication permission signal to the communication interface 20 to give permission for serial communication between the microcomputer 30 and the communication interface 20.

Timing 3 is the falling timing of the communication clock signal transmitted by the microcomputer 30, and the on / off detection signal of the first bit of the register unit 22 is sent to the microcomputer 30. At the same time, the switching unit 24 is switched to send the first on / off detection signal S1 of the first bit of the input latch unit 21 to the comparison unit 23, and the second on / off detection of the first bit sent from the register unit 22 to the microcomputer 30. The signal S2 is sent to the comparison unit 23 via the branch line 14 of the conductor 13.
Timing 4 is the rising timing of the communication clock signal transmitted by the microcomputer 30, and the comparison unit 23 compares the first on / off detection signal S1 and the second on / off detection signal S2. When the first on / off detection signal S1 and the second on / off detection signal S2 are the same, the comparison unit 23 outputs, for example, “1”, assuming that no communication abnormality has occurred, and an error bit via the holding unit 25. Write to 21a.

At timing 5, the second bit on / off detection signal of the register unit 22 is sent to the microcomputer 30, and at the same time, the switching unit 24 is switched and the second on / off detection signal S 1 of the input latch unit 21 is sent to the comparison unit 23. Sent.
At timing 6, the comparison unit 23 compares the first on / off detection signal S1 and the second on / off detection signal S2. In the example of FIG. 2, since the first on / off detection signal S1 and the second on / off detection signal S2 are different, the comparison unit 23 outputs “0” and writes the error bit 21a via the holding unit 25.

At timing 7, the on / off detection signal of the third bit of the register unit 22 is sent to the microcomputer 30, and at the same time, the switching unit 24 is switched and the first on / off detection signal S 1 of the third bit of the input latch unit 21 is sent to the comparison unit 23. Sent.
At timing 8, the comparison unit 23 compares the first on / off detection signal S1 and the second on / off detection signal S2. In the example of FIG. 2, since the first on / off detection signal S <b> 1 and the second on / off detection signal S <b> 2 are the same, the comparison unit 23 outputs “1” to the holding unit 25. However, the holding unit 25 outputs “0” once at timing 6, and once the holding unit 25 outputs “0”, the transmission of the on / off detection signals of all the switches 11 of the input latch unit 21 to the microcomputer 30 is completed. Since the output is held at “0” until then, the value of the error bit 21a is kept at “0”.

As described above, after the input latch unit 21 sends the on / off detection signals of all the switches 11 to the register unit 22, the value of the error bit 21 a, that is, the determination result of the communication abnormality is finally sent to the register unit 22. The unit 22 transmits the determination result to the microcomputer 30.
The microcomputer 30 performs processing such as a request for retransmission of the on / off detection signal to the communication interface 20 based on the determination result.

According to the present invention, the on / off detection signal transmitted from the communication interface 20 to the microcomputer 30 is directly input from the switch 11 and stored in the input latch unit 21 with the least possibility of noise being mixed. By comparing, it is possible to accurately detect the communication abnormality of the on / off detection signal transmitted from the communication interface 20 to the microcomputer 30.
Further, since the register 22 of the communication interface 20 determines the communication abnormality at the timing when the on / off detection signal is transmitted to the receiving side IC, it is possible to prevent the occurrence of a time lag such as the communication abnormality determination being delayed by one cycle.

FIG. 3 shows a second embodiment of the present invention.
In the second embodiment, the communication interface 20 and the microcomputer 30 are mounted on separate printed circuit boards 12a and 12b, and the conductor 13 on the printed circuit board 12 and the jumper wire connecting the conductors 13 are connected to the comparison unit 23. The wiring has the branched line 14.
Also according to the present invention, it is possible to accurately detect a communication abnormality in an on / off detection signal transmitted from the communication interface 20 to the microcomputer 30.
In addition, the separate printed circuit board 12 may be accommodated in the same housing, or may be accommodated in a separate housing.
In addition, since another structure and an effect are the same as that of 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

It is a block diagram which shows 1st Embodiment of the vehicle-mounted electronic control apparatus which is this invention. It is a timing chart which shows operation | movement of an electronic control apparatus. It is a block diagram which shows 2nd Embodiment of the vehicle-mounted electronic control apparatus.

Explanation of symbols

10 Electronic control unit (ECU)
DESCRIPTION OF SYMBOLS 11 Switch 12 of vehicle equipment Printed circuit board 13 Conductor 14 Branch line 20 Communication interface 21 Input latch part 21a Error bit 22 Register part 23 Comparison part 24 Switching part 25 Holding part 30 Microcomputer S1 1st on-off detection signal S2 2nd on-off detection signal

Claims (6)

A transmission side IC having a communication interface for receiving an on / off detection signal of a switch of an in-vehicle device, and a reception side IC for receiving the on / off detection signal from the transmission side IC via a wiring, the reception side IC receiving An on-vehicle electronic control device equipped with an on / off detection signal abnormality check function,
The communication interface of the transmission side IC includes an input latch unit having a bit assigned for each on / off detection signal of a switch to be received, a bit for receiving an on / off detection signal from the input latch unit and each bit, and the received on / off A register unit that sequentially transmits a detection signal to the reception-side IC through the wiring via serial communication;
Furthermore, the transmitting side IC
A comparison unit connected to the branch line branched from the wiring connecting the register unit and the receiving side IC and connected to the input latch unit;
A switching unit that connects to each bit of the input latch unit, and switches the on / off detection signal output from the input latch unit for each switch and inputs the switch to the comparison unit;
The comparison unit compares the on / off detection signal output to the wiring side with the on / off detection signal output for each bit from the input latch unit, and determines that the bit does not match as an error bit. An on-vehicle electronic control device characterized by the above.   The input latch unit includes an error bit for storing a determination result output from the comparison unit, and transmits the determination result of the error bit to the register unit, and the register unit transmits the determination result to the microcomputer. The in-vehicle electronic control device according to claim 1.   The in-vehicle electronic control device according to claim 1, further comprising a holding unit that holds an abnormality determination result between error bits of the comparison unit and the input latch unit.   The transmission side IC and the reception side IC are mounted on the same printed circuit board accommodated in the same housing, and the conductor on the printed circuit board is a wiring having a branch line connected to the comparison unit, or on a separate printed circuit board 4. The vehicle-mounted device according to claim 1, wherein the wiring on the printed circuit board is a wiring having a branch line connecting the conductor and a jumper line connecting the conductors to the comparison unit. 5. Electronic control device.   The transmission side IC and the reception side IC are mounted on a printed circuit board housed in a separate housing, and have a branch line in which a conductor on the printed circuit board and a wire connecting the conductors are connected to the comparison unit The on-vehicle electronic control device according to any one of claims 1 to 3.   The switch connected to the communication interface of the transmission side IC is at least one selected from a door lock switch, an unlock switch, a headlight switch, a sunroof switch, a wiper switch, and an air conditioner switch, and is operated by a passenger. The vehicle-mounted electronic control apparatus of any one of Claims 1 thru | or 5.

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