JPH063456Y2 - Automotive audio equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a reset circuit of a microcomputer constituting a communication system, and particularly to a system composed of two or more microcomputers, each of which communicates via a bus line. The present invention relates to a reset circuit of a configured microcomputer.

<Prior Art> In a system in which microcomputers communicate with each other via a bus line, there is a case where it is desired to connect and disconnect the bus line with a connector. For example, a controller having a control microcomputer that controls the body of a recording medium playing device such as an in-vehicle CD changer may connect a recording medium playing device body controlled by a control microcomputer that receives a control signal from the control microcomputer, a bus line, and the like. An audio device is conceivable in which the controller is detachable and portable by being connected by a connection cable including the connector, and by allowing the connection cable to be separated and connected by the connector.

<Problems to be Solved by the Invention> According to the above audio equipment, when the controller is separated, the power supply for driving the control microcomputer of the controller is turned off, and the drive voltage of this microcomputer (hereinafter referred to as V _DD ).
When the voltage decreases, the control microcomputer needs to send a reset signal to the other control microcomputer via the bus line. In other words, depending on the specifications of the communication system, in order to prevent malfunctions due to data retention, command output, and data loss, the bus line that indicates a reset signal may be output before the microcomputer of the controller completely enters standby. Or, depending on the system specifications, it must be in the “low” state (hereinafter referred to as active high and active low). However, the voltage at which the control microcomputer can operate is generally up to 70% of the rated voltage, and the operation becomes uncertain when the voltage is lower than the rated voltage. Therefore, when V _DD drops, the bus line is used for the time specified by the communication specifications. There is a problem that the reset signal cannot be sent because it cannot be set to active high or active low.

<Means for Solving the Problem> According to the present invention, the above-mentioned problem is solved between an operation unit having a first microcomputer and a controlled device having a second microcomputer and controlled by the operation unit. In an on-vehicle audio device that performs communication via a bus line, a pair of connectors, which are connected to each other when the bus line and the operation unit are mounted, are provided in each of the operation unit and the bus line, and the connector on the bus line side A first power line connected to a power input terminal of the controlled device and a first data line connected to a connection terminal of a second microcomputer of the controlled device, and the operating unit side The connector is provided with a second power line and a second data line connected to the first microcomputer on the operation unit side, and when the connector is separated, the second data line is connected to the first data line more than the first and second data lines. First A second power supply line is separated first, and a power supply cutoff detection unit that detects a cutoff of power supply input to the first microcomputer and a reset signal transmission unit are provided on the operation unit side, When power cutoff is detected by the power cutoff detecting means, a problem is solved by automatically transmitting a reset signal to the second microcomputer via the data line.

<Operation> When the connector is separated, the first and second power supply lines are separated earlier than the first and second data lines. Therefore, the power interruption detecting means inputs the power to the first microcomputer. Is detected, the reset signal transmitting means automatically transmits the reset signal to the second microcomputer via the data line.

<Embodiment> FIG. 1 is a block diagram showing an embodiment of an electronic apparatus according to the present invention. FIG. 2 is a perspective view of the controller of the present invention,
FIG. 3 is a perspective view of the connector connecting portion, and FIG. 4 is a timing chart of the embodiment of the present invention.

In FIG. 1, reference numeral 1 is a CD changer main body which functions to select a predetermined disk from a magazine containing a plurality of disks and reproduce an audio signal, and 2 is a C changer.
A CD changer controller for controlling the D changer 1, which has a rectangular shape as shown in FIG. 2, is relatively small, and can be mounted on a car dashboard using a mounting case (not shown). Alternatively, it can be installed in a car sun visor or the like without using a mounting case, and can be separated from the CD changer body 1 at the connector connecting portion 3 and can be easily carried in a pocket of clothes or the like.

Here, the CD changer controller 2 will be described in detail. Reference numeral 30 denotes a display unit for displaying various display data, and 40.
Is an operation unit consisting of keys for controlling the main body of the CD changer such as play, first word and backward, 50 is a preset memory key for storing the radio reception frequency in advance, and 60 is a time adjustment key,
3A is a bus line connector insertion port.

By inserting the bus line connector 3D of the CD changer body 1 into the connector connecting portion 3 and connecting it to the printed circuit board 3J, power supply and control data can be exchanged between the CD changer controller 2 and the CD changer body 1. become. More specifically, it is as shown in FIG. That is, when the bus line connector 3D of the CD changer body 1 is inserted into the insertion slot 3A, the ground line pattern 3E, the power supply line 3C, and the data pattern 3B with which the contact pieces 3G, 3H, 3I contact each other are the printed circuit board 3J. When the connection is made, the pattern 3E and the contact piece 3G, and similarly 3C and 3H, 3B and 3I are contacted to form a ground line, a power supply line and a data line, and the power supply and the data transfer are performed via the bus line 3F. Since the power supply pattern 3C is formed shorter than the other two patterns at the time of separation, the power supply pattern 3C and the contact piece 3H are separated earlier than the ground line and the data line, and the power is turned off. It is possible to send and receive data for a while after the start. 3K is a joint box for electrically connecting the bus line 3F and the bus line connector 3D.

Next, each part of the CD changer controller 2 will be described. In FIG. 1, 4 is a first microcomputer that transmits and receives data to and from the second microcomputer 7 via a bus line, and 8 is a drive voltage V _DD and a reset output voltage (hereinafter referred to as V _OR ) of the first microcomputer 4. Is a regulator that controls
It has a characteristic that V _DD and V _OR are output by transforming a battery input voltage (hereinafter referred to as V _CC ), and V _OR becomes 0 (V) when V _DD drops below a predetermined voltage value. There is. 5 outputs V _DD from the collector of the transistor Q ₁ to the bus line controller 5A via the diode D ₁ by satisfying the conditional expression of V _OR ≦ V _DD −0.6 to make the bus line active high or active low. It is a reset circuit. Reference numeral 9 denotes a manual reset circuit, which is intended to reset the entire system by the user's discretion, and the above operation can be performed by pressing a transistor Q ₂ that discharges the capacitor C ₂ and resets the entire system. The switch Sw, the resistors R ₃ and R ₄ , and the capacitor C ₁ are used.

The operation of the embodiment of the present invention will be described with reference to FIG. (A) shows the relationship between V _DD output and time, (B) shows V
FIG. 5 is a diagram showing a relation between _OR output and time, (C) is a diagram showing a relation between collector voltage and time, and (D) is a diagram showing a relation between bus line voltage and time.

Now, assuming that the connector connection portion 3 is separated, the circuit is naturally not supplied with power, so that V _DD is 0 volt (V) at time T ₀ . next,
When the connector connection part 3 is connected, power is supplied and T ₁
In V, when V _DD is increased to 0.6 (V), the bipolar transistor Q ₁ outputs 0.6 (V) to the collector,
The collector output is input to the first bus line controller 5A to make the bus line active low. Similarly T ₁
, V _OR is 0 (V), but the bus line is in the active low state, and as a result, the second microcomputer 7 of the CD changer main body is reset by the second bus line controller 6. In addition, V _{DD at} T ₂
Is increased to reach the rated voltage value, the conditional expression V _OR ≦ V _DD ≦ V _DD −0.6 for making the bus line active low is not satisfied, and therefore V _OR is after a delay time Td seconds determined by the size of the capacitor C _2. It is output from the regulator 8 at the rated voltage value of V _DD . On the other hand, the collector output of the transistor Q ₁ continues to increase from T ₁ to T ₂ , becomes 0 (V) after maintaining a steady state for Td seconds, reset is completed, and the bus line is also in the active low state. By the above operation, the bus line becomes active low for the necessary reset time, and the second microcomputer 7 is reset during the active low.

Next, at T ₃ , the printed circuit board 3 of the connector connecting portion 3
When J and the bus line connector 3D are separated and V _DD decreases below a predetermined voltage value V _R (V) at T ₄ , V
_{Since OR} becomes 0 (V) and the conditional expression V _OR ≦ V _DD −0.6 that makes the bus line active low is satisfied, V _DD at T ₄ is output to the collector of the transistor Q ₁ and the bus line becomes active low. The second microcomputer 7 is reset by the second bus line controller 6.
V _DD is 0.6 (V) and made up to the collector of the transistor Q ₁ is the output V _DD bus lines in a subsequent T ₅ maintains the status of the active-low. Further, V _DD becomes 0.6 (V) or less from T ₅ to T ₆ , and thereafter the connector connecting portion 3
Are completely separated.

<Effects> As described above, according to the present invention, an in-vehicle device that communicates via a bus line between an operation unit including a first microcomputer and a controlled device that includes a second microcomputer and is controlled by the operation unit. In the audio equipment for use, a pair of connectors, which are connected to each other when the bus line and the operation unit are mounted, are provided in each of the operation unit and the bus line, and a power input of the controlled device is input to the connector on the bus line side. A first power line connected to the end and a first data line connected to a connection terminal of the second microcomputer of the controlled device are provided, and a second power line is connected to the connector on the operation unit side. And a second data line connected to the first microcomputer on the operation section side is provided, and when the connector is separated, the first and second power supply lines are connected more than the first and second data lines. First The operation section side is provided with a power interruption detection means for detecting interruption of the power input to the first microcomputer and a reset signal transmission means, and the power interruption detection means detects the power interruption. Then, since the reset signal is automatically transmitted to the second microcomputer via the data line,
When the operating unit is separated from the controlled device such as a CD changer, the microcomputer on the controlled device side can be automatically reset without using a special configuration such as a reset line, which enables cost reduction. The operability is improved significantly.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is a block diagram, FIG. 2 is a perspective view of a CD changer controller, FIG. 3 is a perspective view of a connector connecting portion, and FIG. 4 is timing. It is a chart figure. 1 ... CD changer main body, 2 ... CD changer controller, 3 ... connector connection part, 3D ... bus line connector, 3J ... connector insertion port, 4 ... first microcomputer, 5 ... reset circuit, 5A ... first bus line controller, 6 ... 2nd bus line controller, 7 ... 2nd microcomputer, 8 ... Regulator.

Claims (1)

[Scope of utility model registration request] 1. An in-vehicle audio device for performing communication between a control unit having a first microcomputer and a controlled device, which is controlled by the control unit and has a second microcomputer, via a bus line. A pair of connectors, which are connected to each other when the bus line and the operation unit are mounted, are provided on the operation unit and the bus line, respectively, and the bus line side connector is connected to a power input terminal of the controlled device. A first power supply line and a first data line connected to a connection terminal of a second microcomputer of the controlled device are provided, and a connector on the operation unit side has a second power supply line and the operation unit. A second data line connected to the first microcomputer on the side is provided, and when the first and second connectors are separated, the first and second
A first power supply line and a second power supply line separated from the second data line first, and a power cutoff detecting means for detecting the cutoff of the power input to the first microcomputer on the operation unit side. An in-vehicle audio device, comprising: a reset signal transmitting means, and transmitting a reset signal to the second microcomputer via the data line when the power interruption detecting means detects a power interruption.