JPH08308008A - Communication equipment with resetting function - Google Patents

Abstract

PURPOSE: To provide a communication equipment which is adapted for a communication system in a battery monitoring system for an electric vehicle and in which the failure reset of a communication channel can be achieved. CONSTITUTION: A communication equipment comprises a voltage holding capacitor, a charge control resistor for deciding the charging current of the capacitor, and a runaway protective circuit 4 having a discharge control resistor for deciding the discharge current of the capacitor between at least one of a transmitting element 2 and a receiving element 3 and the reset terminal of a microcomputer 1. When a low-level output is continuously output to the channel connected to the element 2 or the element 3, the circuit 4 resets the microcomputer 1 to easily reset against the failure of the channel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device with a reset function suitable for a battery monitoring system for electric vehicles.

[0002]

2. Description of the Related Art In recent years, practical electric vehicles have been developed at a rapid pace, and a battery monitoring system for electric vehicles is also required to have a simpler structure and higher accuracy. Usually, 24 batteries are connected in series as a battery system of an electric vehicle, and a communication path is provided between the batteries for transmitting information of each battery connected in series to the main computer of the electric vehicle by communication. Since the potential of each battery is different, it is necessary to insulate the communication line of the communication path from the potential of each battery. In this case, it is desirable to reduce the number of communication lines forming the communication path as much as possible. As a conventional technique, 4-wire and 2-wire communication systems that do not use a control line can be considered.

A conventional communication device will be described below with reference to the drawings. FIG. 7 shows a conventional communication device. 1
Is a microcomputer and has a function of controlling communication. 2 is a transmitting element, which is connected to the data output terminal of the microcomputer 1,
It is also connected to a communication path for communicating with the outside. A receiving element 3 is connected to the data input terminal of the microcomputer 1 and is also connected to a communication path for communicating with the outside.

The operation of the communication device configured as described above will be described below. When transmitting data, the microcomputer 1 outputs the data to be transmitted from the data output terminal. The transmitting element 2 level-converts the data from the microcomputer 1 so as to have the signal level of the communication path and outputs the data to the communication path. In the following description, communication is performed by setting the communication path to low level (active low). That is, when there is no data, the communication path is at a high level.

When receiving data, the receiving element 3 converts the data on the communication path into the signal level of the microcomputer 1, and the microcomputer 1 reads this value from the data input terminal.

FIG. 6 shows a two-wire communication system. In the case of a two-wire communication system, since the transmitting element 2 and the receiving element 3 are connected to the same communication path, only one of the communication devices can transmit at a certain time, and the others are in the receiving state. Must. Therefore, normally, one of the communication devices is special for controlling communication, and the other communication devices are subject to the control. This special communication device will be called a master communication device, and the others will be called slave communication devices. However, when two or more communication devices simultaneously transmit data due to some abnormality, the data on the communication path becomes erroneous, and it may be difficult to return from that state to a normal state. In the worst case, a certain communication device becomes abnormal, continues to output a low level signal, and if there is no data, the communication path that should be high level is fixed at low level, all communication becomes impossible, It is very difficult to restore this communication system to normal.

In the 4-wire communication system, since the transmission communication path and the reception communication path are separately provided, when an abnormal signal is detected in one communication path, the other communication path can be used to try to recover. Compared with the two-wire communication system, it is easy to recover from a communication error. However, even in the 4-wire communication system, the communication path may be fixed at a low level and may not be recovered. Further, even in a four-wire or more communication system using a control line, the data communication line may be fixed at a low level and it may be difficult to recover. In either case, if the communication path becomes abnormal, It is desirable to be able to try to recover an abnormal communication device by resetting.

[0008]

Although a two-wire communication system is desirable as a battery monitoring system from the viewpoint of hardware cost, it has a problem that it is difficult to restore the communication path in the event of an abnormality as described above. It was

The present invention solves the above-mentioned conventional problems and is a reset for facilitating recovery from an abnormality in both a two-wire communication system and a four-wire or more communication system. An object is to provide a communication device with a function.

[0010]

In order to solve the above conventional problems, a communication device with a reset function according to the present invention includes a capacitor for holding a voltage, a charging control resistor for determining a charging current of the capacitor, and A runaway protection circuit having a discharge control resistor that determines a discharge current of the capacitor is provided between at least one of the transmitting element and the receiving terminal and the reset terminal of the microcomputer.

[0011]

With this configuration, when the low-level output is continuously output to the communication path, the runaway protection circuit resets the microcomputer to restore the communication path, thereby facilitating recovery from the abnormality in the communication path. .

[0012]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 is a microcomputer having a function of controlling communication. A transmitting element 2 is connected to the data output terminal of the microcomputer 1 and is also connected to the communication path 1 for communicating with the outside. A receiving element 3 is connected to the data input terminal of the microcomputer 1 and is also connected to the communication path 2 for communicating with the outside. Reference numeral 4 is a runaway protection circuit, which is connected to the transmitting element 2 and whose output is the microcomputer 1
Connected to the reset terminal of.

FIG. 2 shows the runaway protection circuit described above. 41
Is a charge control resistor and is connected to the transmitting element 2 through the diode 46. A capacitor 42 is connected between the charge control resistor and the ground. Reference numeral 43 is a discharge control resistor, which is connected in parallel with the capacitor 42.
A current limiting resistor 44 is connected to the capacitor 42. A Zener diode 45 is connected between the current limiting resistor 44 and the ground. A diode 47 is connected between the output of the runaway protection circuit 4 and the reset terminal of the microcomputer 1.

The operation of the communication device with reset function configured as described above will be described with reference to FIG.
Normal data communication is performed similarly to the conventional communication device.
When the communication path is fixed to the low level, the communication device outputting the low level output resets itself as follows.

In the case of a normal communication signal, there is a 1-bit high level signal (stop bit) for at least one data unit. Due to the stop bit, the capacitor 42 is charged with sufficient electric charge not to turn off the reset terminal of the microcomputer 1 through the charge control resistor 41. After the voltage of the capacitor 42 is limited to the reset terminal voltage input range of the microcomputer 1 by the Zener diode 45 through the current limiting resistor 44,
It is input to the reset terminal of the microcomputer 1. The Zener diode 47 is inserted to separate it from the original reset circuit of the microcomputer 1. If there is a high level bit other than the stop bit, it is also charged by that bit. When the communication path becomes low level, the charge of the capacitor 42 is discharged through the discharge control resistor 43, but the capacitor 42 turns off the reset terminal of the microcomputer 1 even when the communication line sends a signal of 00 ... 0. Do not maintain the charge control resistor 4 so as to maintain a sufficient voltage.
1, the constants of the discharge control resistor 43 and the capacitor 42 are determined. When the transmitting element continues to output a low level due to an abnormality, the electric charge charged in the capacitor 42 is discharged through the discharge control resistor 43. When the voltage across the capacitor 42 becomes lower than the reset voltage of the microcomputer 1, the microcomputer 1 is reset. Further, when the microcomputer 1 becomes inoperable, the data output terminal of the microcomputer 1 is generally turned off. At this time, the communication device with the reset function is disconnected from the communication path, and communication with another communication device with the reset function is performed. Does not affect

When the two-wire communication system shown in FIG. 6 is configured by using the communication device with reset function shown in the first embodiment of the present invention, normal data communication is the same as when configured by using the conventional communication device. Can be operated. When the communication path becomes fixed to the low level, the communication device with reset function that outputs the low level is automatically reset, so the communication path is also reset and normal data communication is resumed. It is possible to

(Embodiment 2) FIG. 4 shows a second embodiment of the present invention. In FIG. 4, reference numeral 1 is a microcomputer, which has a function of controlling communication data. A transmitting element 2 is connected to the data output terminal of the microcomputer 1 and is also connected to a communication path for communicating with the outside. 3 is a receiving element,
It is connected to the data input terminal of the microcomputer 1 and also connected to a communication path for communicating with the outside. Reference numeral 4'denotes a runaway protection circuit, which is connected to the receiving element 3 and its output is connected to the reset terminal of the microcomputer 1. The runaway protection circuit 4'has the same configuration as the runaway protection circuit 4 shown in FIG. 2, and the diode 46 is connected to the receiving element 3 instead of the transmitting element 2.

The operation of the communication device with reset function configured as described above will be described. Normal data communication is performed similarly to the conventional communication device. When the communication path is fixed at a low level due to an external factor, the runaway protection circuit 4'resets the microcomputer 1 as in the first embodiment.

When the two-wire communication system shown in FIG. 6 is constructed using the communication device with reset function shown in the second embodiment of the present invention, only the master communication device does not have the conventional reset function. To use.

As the operation of this system, normal data communication can be performed in the same manner as in the case of using a conventional communication device. When the master communication device that controls communication detects an abnormality during data communication, all slave units can be reset as follows.

The master communication device outputs a low level from the transmitting element 2 and fixes the communication path at the low level for a certain period of time. As a result, the receiving element 3 of the slave communication device receives an abnormal low level signal, the runaway protection circuit 4 ′ resets the microcomputer 1, and all slave communication devices are reset. The master communication device returns the communication path to the high level and restarts communication.

(Embodiment 3) FIG. 5 shows a third embodiment of the present invention. In FIG. 5, reference numeral 1 is a microcomputer, which has a function of controlling communication. 2 is a transmitting element, and the microcomputer 1
Connected to a data output terminal, and also connected to a communication path for communicating with the outside. A receiving element 3 is connected to the data input terminal of the microcomputer 1 and is also connected to a communication path for communicating with the outside. 4 is a runaway protection circuit,
It is connected to the transmitting element 2 and its output is connected to the reset terminal of the microcomputer 1. Reference numeral 4'denotes a runaway protection circuit, which is connected to the receiving element 3 and its output is connected to the reset terminal of the microcomputer 1. Reference numeral 5 is an OR gate, which inputs any one of the outputs of the runaway protection circuits 4 and 4'to the reset terminal of the microcomputer 1.

The operation of the communication device with a reset function configured as described above will be described. Normal data communication is performed similarly to the conventional communication device. When the low level is continuously output to the communication path through the transmitting element, the same operation as that in the first embodiment is performed, and when the communication path is fixed to the low level due to an external factor, the above operation is performed. The microcomputer 1 is reset by the same operation as that shown in Example 2.

When the two-wire communication system shown in FIG. 6 is constructed using the communication device with reset function shown in the third embodiment of the present invention, only the master communication device does not have the conventional reset function. To use.

As the operation of this system, normal data communication can be performed in the same manner as in the case where the conventional communication device is used. When the communication path is fixed to the low level, the communication apparatus with the reset function that outputs the low level is automatically reset as in the case of the first embodiment. It is reset and the communication path can be restored. When the master communication device that controls communication detects an abnormality during data communication, all slave units are reset in the same manner as in the second embodiment.
Communication can be resumed.

[0027]

As described above, according to the present invention, the voltage holding capacitor, the charge control resistor for determining the charge current of the capacitor, and the discharge control resistor for determining the discharge current of the capacitor are provided. By providing a runaway protection circuit between at least one of the transmitting element and the receiving element and the reset terminal of the microcomputer, if the low level output continues to be output to the communication path, the runaway protection circuit resets the microcomputer and It is possible to provide a communication device with a reset function that can easily recover from an abnormality in a communication path by returning the communication path.

[Brief description of drawings]

FIG. 1 is a block diagram showing a communication device with a reset function according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a runaway protection circuit used in the communication device.

FIG. 3 is an operation explanatory diagram of the runaway protection circuit.

FIG. 4 is a block diagram showing a communication device with a reset function according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a communication device with a reset function according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing a conventional two-wire communication system.

FIG. 7 is a block diagram showing a conventional communication device.

[Explanation of symbols]

 1 Microcomputer 2 Transmitting Element 3 Receiving Element 4, 4'Runaway Protection Circuit 41 Charge Control Resistor 42 Capacitor 43 Discharge Control Resistor 44 Current Limiting Resistor 45 Zener Diode 46, 47 Diode

Claims (3)

[Claims] 1. A communication device comprising a transmission terminal connected to a data output terminal of a microcomputer and a reception terminal connected to a data input terminal of the microcomputer, wherein a voltage holding capacitor and a charging current of the capacitor are provided. A communication device with a reset function, wherein a runaway protection circuit including a charge control resistor that determines the discharge current and a discharge control resistor that determines the discharge current of the capacitor is provided between the transmission element and the reset terminal of the microcomputer. 2. The communication device with a reset function according to claim 1, further comprising a runaway protection circuit provided between the receiving element and the reset terminal of the microcomputer. 3. The communication device with a reset function according to claim 1, wherein a runaway protection circuit is provided between the transmitting element and the reset terminal of the microcomputer and between the receiving element and the reset terminal of the microcomputer.