JP2021104795A - On-vehicle instrument - Google Patents

Abstract

To provide an on-vehicle instrument in which a CPU can be restored from an abnormal condition even during travelling of a vehicle.SOLUTION: An on-vehicle instrument comprises: a power source circuit that receives power supply from a battery in a vehicle to generate an inner voltage; an abnormality determination circuit that determines whether the CPU is in an abnormal state on the basis of return signals from the CPU corresponding to periodic interrupt signals; and a power source control circuit that restarts the CPU by temporarily cutting off power supply from the power source circuit to the CPU, when the CPU is determined to be in the abnormal state.SELECTED DRAWING: Figure 1

Description

The present invention relates to an on-board unit.

In general, an on-board unit such as an ETC on-board unit operates by receiving electric power from a vehicle battery (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-146249

Since the power of the on-board unit of the above-mentioned on-board unit is not turned off unless the engine of the vehicle is stopped, it is difficult to recover the on-board unit if the CPU of the on-board unit becomes abnormal while the vehicle is running.

The present invention has been made in view of the above problems, and a main object thereof is to provide an in-vehicle device capable of recovering a CPU from an abnormal state even while the vehicle is running.

In order to solve the above problems, the vehicle-mounted device according to one aspect of the present invention includes a CPU, a power supply circuit that receives power from a vehicle battery and generates an internal voltage, and the CPU corresponding to a periodic interrupt signal. An abnormality determination circuit for determining whether or not the CPU is in an abnormal state based on the return signal from the CPU, and a power supply circuit for supplying power to the CPU when the CPU is determined to be in an abnormal state. It includes a power supply control circuit that restarts the CPU by temporarily shutting it off.

According to the present invention, it is possible to recover the CPU from an abnormal state even while the vehicle is running.

It is a block diagram which shows the structural example of the vehicle-mounted device which concerns on embodiment. It is a timing diagram which shows the operation example of an in-vehicle device. It is a timing diagram which shows the operation example of an in-vehicle device. It is a timing diagram which shows the operation example of an in-vehicle device. It is a timing diagram which shows the operation example of an in-vehicle device. It is a timing diagram which shows the operation example of an in-vehicle device. It is a timing diagram which shows the operation example of an in-vehicle device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration example of the vehicle-mounted device 1 according to the embodiment. The on-board unit 1 is, for example, an ETC on-board unit used in an electronic toll collection system (ETC). The vehicle-mounted device 1 operates by receiving electric power from the battery of the vehicle.

The vehicle-mounted device 1 includes a wireless communication unit 2, a memory 3, an LED 4, a voice circuit 5, a speaker 6, a power supply circuit 7, a power supply control circuit 8, an abnormality determination circuit 9, and a CPU 10. The abnormality determination circuit 9 includes a periodic circuit 91 and a delay circuit 92.

In addition, the vehicle-mounted device 1 may further include a GNSS (Global Navigation Satellite System) receiver or the like.

The CPU 10 executes information processing according to a program. The program is stored in an information recording medium such as a memory 3. The memory 3 is a non-volatile memory such as a flash memory.

The wireless communication unit 2 is a unit for wireless communication with the roadside unit. The signal processing by the wireless communication unit 2 is performed according to, for example, a DSRC (Dedicated Short Range Communication) standard.

The power supply circuit 7 receives power from the vehicle battery and generates an internal voltage. The power supply circuit 7 includes, for example, a DC / DC converter (switching regulator). The power supply circuit 7 may further include an LDO regulator (linear regulator).

The connection type between the vehicle battery and the power supply circuit 7 may be a two-wire system including two wires of an accessory power supply line (ACC) and a ground line (GND), or a three-wire system including a constant power supply line. It may be an expression.

The power supply control circuit 8 controls the power supply from the power supply circuit 7 to the CPU 10. For example, the power supply control circuit 8 starts supplying electric power from the power supply circuit 7 to the CPU 10 when it receives a signal indicating that the ignition switch is ON from the vehicle side.

Further, when the power supply control circuit 8 receives the power supply control signal from the abnormality determination circuit 9, the power supply control circuit 8 temporarily shuts off the power supply from the power supply circuit 7 to the CPU 10 to restart the CPU 10.

Specifically, the power supply control circuit 8 is composed of, for example, an LDO regulator (linear regulator), and switches between supplying and cutting off power from the power supply circuit 7 to the CPU 10 according to a power supply control signal input to the EN terminal.

The abnormality determination circuit 9 is provided outside the CPU 10, and determines whether or not the CPU 10 is in an abnormal state based on the return signal from the CPU 10 corresponding to the periodic interrupt signal to the CPU 10. The abnormal state means, for example, a state in which the CPU 10 is frozen.

Specifically, the periodic circuit 91 generates a periodic interrupt signal and outputs it to the CPU 10. If the return pulse of the return signal is input within a predetermined time after the L / H level of the interrupt signal is inverted, the delay circuit 92 does not output the restart pulse of the power supply control signal and does not output the interrupt signal. If the return pulse of the return signal is not input within a predetermined time after the L / H level of is inverted, the restart pulse of the power supply control signal is output.

In other words, if the return pulse of the return signal is input within a predetermined time after the L / H level of the interrupt signal is inverted, it is determined that the CPU 10 is in a normal state, and the L / H level of the interrupt signal is determined. If the return pulse of the return signal is not input within a predetermined time after the inversion, the CPU 10 is determined to be in an abnormal state.

In the present embodiment, the delay circuit 92 is an analog type delay circuit using a resistor and a capacitor, but a digital watchdog timer using a counter may be applied instead.

2 to 7 are timing diagrams showing an operation example of the vehicle-mounted device 1.

Each part included in the vehicle-mounted device 1 receives power and operates when the IG signal indicating the state of the ignition switch is at the H level corresponding to the ON state.

The periodic circuit 91 generates an interrupt signal that changes periodically. The delay circuit 92 starts charging the capacitor with the falling edge of the interrupt signal as a trigger. Not limited to this, the rising edge of the interrupt signal may be used as a trigger.

The parameter represents the execution of the task by the CPU 10. The task is a task for realizing the function as an in-vehicle device. In the example of the figure, a parameter indicating the execution of the communication task, that is, indicating that communication is in progress is shown.

The tasks include, for example, a communication task for communicating with a roadside machine, an external IF task for communicating with another device, an HMI task for notifying a user, a security task, a timer task, and the like.

The HMI (Human Machine Interface) task is accomplished by driving an LED 4, an audio circuit 5, and a speaker 6 (see FIG. 1).

As shown in FIG. 2, the CPU 10 performs a self-diagnosis triggered by a fall of an interrupt signal. The self-diagnosis is a process of determining whether or not an abnormality has occurred in all the tasks executed by the CPU 10.

As shown in FIG. 3, when a communication task or the like is being executed when the interrupt signal falls, the CPU 10 performs a self-diagnosis after the communication task or the like is completed.

As shown in FIGS. 2 and 3, if no abnormality has occurred in all the tasks as a result of the self-diagnosis, the CPU 10 outputs a return pulse of the return signal. The return pulse of the return signal is output as, for example, an H-level single-shot pulse. When the delay circuit 92 detects the return pulse of the return signal, it does not output the restart pulse of the power control signal. Therefore, the CPU 10 is not restarted.

As shown in FIG. 4, when there is a task determined to have an abnormality as a result of the self-diagnosis, the CPU 10 executes the recovery of the task determined to have an abnormality by software processing.

As shown in FIG. 5, when a communication task or the like is being executed when the self-diagnosis is completed, the CPU 10 uses software processing to recover the task determined to have an abnormality after the communication task or the like is completed. implement.

As shown in FIGS. 4 and 5, when the task determined to have an abnormality is successfully recovered, the CPU 10 outputs a return pulse of the return signal. When the delay circuit 92 detects the return pulse of the return signal, it does not output the restart pulse of the power control signal. Therefore, the CPU 10 is not restarted.

As shown in FIGS. 6 and 7, when the recovery of the task determined to have an abnormality fails, the CPU 10 does not output the return pulse of the return signal. The delay circuit 92 outputs a restart pulse of the power supply control signal when a predetermined time corresponding to the time constant elapses without detecting the return signal. As a result, the CPU 10 is restarted.

The restart pulse of the power supply control signal is output as, for example, an L-level single-shot pulse, and cuts off the power from the power supply circuit 7 to the CPU 10 during the L-level period. Specifically, the power supply control signal falls when the delay circuit 92 elapses for a predetermined time, and then rises when the interrupt signal of the periodic circuit 91 rises.

By such an operation of the abnormality determination circuit 9, the CPU 10 can be restarted even while the vehicle is running. Further, by recovering the task determined to be abnormal by the self-diagnosis by software processing at the beginning, it is possible to avoid unnecessary restart of the CPU 10.

As described below, when the CPU 10 does not output the return pulse of the return signal, the CPU 10 stores predetermined data such as status data indicating the execution of the restart and the toll office data used for executing the communication task and the like. You may write to 3 and read from memory 3 after restarting.

As shown in FIG. 6, when the return pulse of the return signal is not output, the CPU 10 writes the status data indicating the execution of the restart to the memory 3 and reads it from the memory 3 after the restart. When the CPU 10 reads the status data, the CPU 10 limits the execution of the card authentication notification using the LED 4 and the speaker 6.

When the CPU 10 is restarted, it is necessary to re-execute the card authentication of the ETC card, but if the notification that the card authentication is completed while the vehicle is running, the occupant may feel uncomfortable. Therefore, in order to reduce the discomfort of the occupants, the implementation of the card authentication notification is restricted at the time of restarting.

Not limited to this, as shown in FIG. 7, the CPU 10 may execute a restart notification for notifying the user of the execution of the restart when the return pulse of the return signal is not output. The restart notification is carried out using the LED 4 and the speaker 6. This also makes it possible to reduce the discomfort of the occupants.

Further, as shown in FIG. 7, when the CPU 10 does not output the return pulse of the return signal, the tollhouse data or the like used for executing the communication task or the like is written to the memory 3 and read from the memory 3 after restarting. put out. The CPU 10 uses the tollhouse data or the like read from the memory 3 to execute a communication task or the like.

When driving on a toll road, it is necessary to retain the tollhouse data obtained from the roadside machine of the tollhouse and use it at the time of payment. Therefore, when the CPU 10 is restarted, the tollhouse data or the like used for executing the communication task or the like is temporarily saved in the memory 3, so that a smooth recovery can be facilitated.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and it goes without saying that various modifications can be made to those skilled in the art.

The period of the interrupt signal output by the cycle circuit 91 may be set based on the installation interval of the roadside unit that wirelessly communicates with the vehicle-mounted device 1. For example, in ETC 2.0, since the ITS spots are installed at intervals of 200 m or more, it is preferable that the cycle is shorter than the traveling time in which the vehicle travels 200 m.

That is, the period of the interrupt signal is set shorter than the traveling time obtained by dividing the installation interval of the roadside unit by the vehicle speed. Here, the period of the interrupt signal may be set in advance with the vehicle speed as a constant value, or the vehicle speed may be acquired based on GNSS data (GPS data) or the like, and the period of the interrupt signal may be dynamically changed. You may.

1 in-vehicle device, 2 wireless communication unit, 3 memory, 4 LED, 5 voice circuit, 6 speaker, 7 power supply circuit, 8 power supply control circuit, 9 abnormality judgment circuit, 91 cycle circuit, 92 delay circuit, 10 CPU

Claims (11)

CPU and
A power supply circuit that receives power from the vehicle battery and generates an internal voltage,
An abnormality determination circuit that determines whether or not the CPU is in an abnormal state based on a return signal from the CPU corresponding to a periodic interrupt signal.
A power supply control circuit that restarts the CPU by temporarily cutting off the power supply from the power supply circuit to the CPU when it is determined that the CPU is in an abnormal state.
In-vehicle device. When the CPU receives the interrupt signal, the CPU performs a self-diagnosis for determining whether or not an abnormality has occurred in one or a plurality of tasks executed by the CPU.
The vehicle-mounted device according to claim 1. The CPU recovers a task determined by the self-diagnosis that an abnormality has occurred.
The vehicle-mounted device according to claim 2. The CPU does not transmit the return signal when the task determined to have the abnormality is not recovered.
The vehicle-mounted device according to claim 3. When a predetermined task is executed at the time of receiving the interrupt signal, the CPU performs the self-diagnosis after the completion of the predetermined task.
The vehicle-mounted device according to any one of claims 2 to 4. When the predetermined task is executed when the self-diagnosis is completed, the CPU restores the task after the predetermined task is completed.
The vehicle-mounted device according to claim 3 or 4. When the CPU does not transmit the return signal, it writes predetermined data to the memory, and after restarting, reads the data from the memory.
The vehicle-mounted device according to any one of claims 1 to 6. The CPU
When the return signal is not transmitted, data indicating the execution of the restart is written to the memory.
When the data is read from the memory after restarting, the execution of a predetermined operation is restricted.
The vehicle-mounted device according to claim 7. The CPU
When the return signal is not transmitted, the data used for executing the task is written to the memory, and the data is written to the memory.
After restarting, the data is read from the memory and used for executing the task.
The vehicle-mounted device according to claim 7. The CPU performs an operation for notifying the user of the restart when the return signal is not transmitted.
The vehicle-mounted device according to any one of claims 1 to 9. The period of the interrupt signal is set based on the installation interval of the roadside unit that wirelessly communicates with the on-board unit.
The vehicle-mounted device according to any one of claims 1 to 10.

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