JPH07200114A - Bus circuit device - Google Patents

Abstract

PURPOSE:To operate a bus circuit fast by preventing the state of the load on a shared electric circuit from changing with the number and arrangement of circuit boards. CONSTITUTION:The shared electric circuit 1 which can be used in common and plural input/output circuits 2 are connected, and dedicated circuits 3 which perform respective characteristic functions are fitted detachably to the input/ output circuit 2 through connectors 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bus circuit device in a high speed electronic circuit device.

[0002]

2. Description of the Related Art In electronic circuit devices, many circuit boards having different functions and bus connections connecting the circuit boards to a shared electric circuit are used to form the electronic circuit device. For example, in a computer or the like, it is common to configure a circuit by connecting a central processing unit (CPU), a memory device, a magnetic disk device, an interface device with an external device, etc. to a shared electric circuit called a system bus by a connector. . In this case, each circuit board is composed of a circuit portion that performs a function unique to the circuit board and a circuit portion that inputs and outputs signals to the shared electric circuit. By connecting this to a shared electric circuit with a connector, it can be attached and detached. As a result, the circuit board can be replaced in the event of a failure, and a new circuit board can be added or omitted, which is widely applied to electronic circuit devices.

In recent years, as the functions of electronic circuit devices increase, the number of circuits connected to the bus increases, and the length of shared electric circuits tends to increase. At this time, the load of wiring and the load of connectors increase, which is an obstacle to speeding up the bus circuit. For example, reference H. Satoh etc. "Analysis of Hig
30 MHz when the number of circuit boards is 5, as shown in "h-speed bus lines in printed circuit boards".
It has also been reported that when the number of buses operating in 20 becomes 20, the bus operates only at about 10 MHz. The main reason for this is that the operation margin is large so that the circuit can operate even if the load state changes when the number of circuit boards is changed.

FIG. 8 shows an example of a conventional bus circuit device.
Is a shared electric circuit, which is formed on the circuit board 11. Two
Is an input / output circuit, and 3 is a dedicated circuit having a function peculiar to the circuit board. For example, as described above, the CPU, the memory device,
Each of the magnetic disk device and the interface device with an external device performs different unique functions. The input / output circuit 2 and the dedicated circuit 3 are formed on a circuit board 31, and the two circuits 2 and 3 are connected by a wiring provided in advance. A connector 4 is provided between each of the circuit boards 11 and 31, and the shared electric circuit 1 and each input / output circuit 2 are detachably connected.

FIG. 9 is a diagram for explaining a load variation due to the tripping of the circuit board 31 in the bus circuit device shown in FIG. 8. Of the twelve circuit boards 31-1 to 31-12, 31-9 is shown. And 31-10 are shown in a removed state. In this way, the state of the load connected to the shared electric circuit 1 changes as the circuit board 31 is attached or detached. This state is shown in FIG.

FIG. 10 is a circuit board 31-shown in FIG.
It is a figure which shows the data for demonstrating the load fluctuation by the removal of 9,31-10, ie, the fluctuation of a propagation waveform.
FIG. 10A shows the circuit board 31 before removal, that is, the entire circuit board 31.
-1 to 31-12 are mounted, the signals are transmitted from the dedicated circuit 3 of the circuit board 31-1, and are received by the dedicated circuit 3 of the circuit board 31-12. A curve A is a transmission waveform and a curve B is reception. The waveform is shown. It can be seen from FIGS. 10A and 10B that the waveform greatly changes when the circuit board 31 is removed.

As described above, in the conventional bus circuit device, the state of the load connected to the shared electric circuit 1 changes when the circuit board 31 is attached or detached. Even if the optimum conditions are set when the maximum number of boards are installed, the waveform changes when the circuit board is removed, so there is a drawback that a high-speed bus cannot be designed.

[0008]

As described above, as the functions of the electronic circuit device increase, the number of circuits connected to the bus increases, the length of the shared electric circuit increases, and the wiring load and connector There is a problem in that the bus circuit device cannot operate at high speed because the load increases and it becomes an obstacle to speeding up the bus circuit.

An object of the present invention is to provide a bus circuit device capable of operating many circuit boards at high speed by keeping the load state of the shared electric circuit unchanged by the number and arrangement of the circuit boards. is there.

[0010]

DISCLOSURE OF THE INVENTION A bus circuit device according to the present invention includes a shared electric circuit that can be commonly used, a dedicated circuit that performs its own function, and a plurality of input / output units that input / output signals to / from the shared electric circuit. In the bus circuit device having a circuit, each of the input / output circuits is provided in advance in the shared electric circuit, and the dedicated circuit and the input / output circuit are respectively connected by a connector.

Each input / output circuit is connected to a common electric circuit by a connector.

Further, each input / output circuit is formed in advance on a circuit board on which a shared electric circuit is formed.

[0013]

In this type of bus circuit device, a major factor of load fluctuation that becomes a problem when the number of circuit boards is changed is that when the circuit boards are attached or detached, the load of the shared electric circuit and the load of the connector are shared. This is because the load of the input / output circuit on the circuit is eliminated or loaded. Therefore, in the present invention, the circuit board is attached / detached by a connector provided between a dedicated circuit having a unique function of the circuit board and an input / output circuit to / from the shared electric circuit. The load fluctuation of the electric circuit section is eliminated, the operation margin when the number of circuits is changed becomes sufficiently small, and the bus circuit device operates at high speed.

Further, since each input / output circuit can be separated from the common electric circuit by the connector, the common electric circuit can be easily replaced for a failure.

Further, since each input / output circuit is formed on the circuit board of the shared electric circuit, the entire size is reduced.

[0016]

【Example】

[First Embodiment] FIG. 1 shows a first embodiment of the present invention, which is applied to a back panel type bus circuit. In FIG. 1, reference numeral 1 denotes a shared electric circuit, which is formed on the circuit board 11. Reference numeral 2 denotes an input / output circuit for the shared electric circuit 1, which is formed on the circuit board 21. Dedicated circuit 3 has a function peculiar to the circuit board and is formed on the circuit board 31. Reference numeral 4 is a connector for detachably connecting the input / output circuit 2 and the dedicated circuit 3.

The input / output circuit 2 to / from the shared electric circuit 1 is an essential circuit because it sends a signal to a circuit to which many circuit boards are connected and cannot be omitted. In this embodiment, instead of attaching the connector 4 to the shared electric circuit 1, the shared electric circuit 1
This is a structure in which a connector 4 is provided next to the input / output circuit 2 for the shared electric circuit 1 directly connected to. As a result, the connection relationship of the shared electric circuit 1 does not change when the dedicated circuit 3 having the function peculiar to the circuit board is attached or detached, and the optimum design of the shared electric circuit 1 can be performed regardless of the number of the circuit boards 3.
The dedicated circuit 3 having a function peculiar to the circuit board is the shared electric circuit 1
No special circuit is required because the signal is not output to the entire circuit, but is sent to only one input / output circuit 2 to / from the shared electric circuit 1.

FIG. 2 shows an example of the configuration of the input / output circuit 2 in the embodiment of FIG. 1. A1 and A2 are amplifiers (logic gates), in and out are input sides and output sides, and R
Indicates a resistor. The amplifier A1 has low impedance when viewed from the shared electric circuit 1, and the amplifier A2 has the same shared electric circuit 1
Seen from the viewpoint, the impedance is high, and the combined impedance of the two is the impedance of the shared electric circuit 1 to the dedicated circuit 3, which is low impedance. In this state, even if the dedicated circuit 3 is removed by the connector 4, the low impedance of the amplifier A1 is hardly affected, and the load fluctuation is eliminated.

FIG. 3 shows another example of the configuration of the input / output circuit 2 in the embodiment of FIG. 1. What is different from the example of FIG. 2 is that instead of the amplifier A1, a control terminal for switching between transmission and reception. This is the point where an amplifier A3 having

The impedance Z ₀ viewed from the shared electric circuit 1 of the amplifier A3 (transmission gate) changes to low impedance during transmission and high impedance during reception when the amplifier A2 operates by applying a control signal to the control terminal. . In this way, the impedance seen from the shared electric circuit 1 varies between transmission and reception, but only one circuit among the plurality of dedicated circuits 3 connected to the shared electric circuit 1 is always transmitted, and the others are Since all the signals are received, there is almost no load fluctuation on the shared electric circuit 1.

FIG. 4 is a diagram for explaining a load variation due to the trip of the circuit board 31 in the first embodiment of FIG.

In the case of FIG. 4 as well, as in FIG.
It shows a case where -9 and 31-10 are removed.

FIG. 5 is a circuit board 31-9, 3 shown in FIG.
It is a figure which shows the data for demonstrating the load fluctuation by removal of 1-10. FIG. 5A shows the characteristics before removal, and when all the circuit boards 31-1 to 31-12 are mounted, FIG. 5B shows the propagation waveform after removal. That is, the curve A is the transmission waveform from the input / output circuit 2 connected to the dedicated circuit 3 of the circuit board 31-1, and the curve B is the circuit board 3.
1 is a reception waveform of the input / output circuit 2 connected to the dedicated circuit 3 of 1-12. It can be seen that there is almost no change in the waveform in both FIGS. [Second Embodiment] FIG. 6 shows a second embodiment of the present invention, in which 5 is a connector for the shared electric circuit 1 and 21 is a circuit board. In this embodiment, the input / output circuit 2 is formed on the circuit board 21, and the connector 4 connects the circuit board 21 and the circuit board 3 together.
1, that is, the input / output circuit 2 and the dedicated circuit 3 are detachably connected. Also in this case, it is obvious that if the circuit board 31 is attached / detached by the connector 4, the load of the shared electric circuit 1 does not change. Further, in this circuit, the connector 5 can easily replace the common electric circuit 1 for a failure. [Third Embodiment] FIG. 7 shows a third embodiment of the present invention. A shared electric circuit 1 shown by a dotted line is formed on one surface of a circuit board 11 and an input / output circuit 2 is shared. An example in which the circuit board 11 is directly attached to the other surface is shown. The circuit connection relationship is the same as that of the embodiment of FIG. 1, and the structure is such that the common electric circuit 1 is branched on the circuit board 11 and is connected by the connector 4 through the input / output circuit 2 on this circuit board 11. Is. In this case, there is an advantage that the entire bus circuit composed of the shared electric circuit 1 and the circuit board 11 can be downsized.

[0024]

As described above, according to the present invention, a shared electric circuit that can be commonly used, a plurality of dedicated circuits each having a unique function, and a plurality of input / outputs for inputting / outputting signals to / from the shared electric circuit are provided. In a bus circuit device having a circuit,
Provide each input / output circuit in the shared electric circuit in advance,
Since the dedicated circuit and the input / output circuit are detachably connected by connectors, load fluctuations and termination conditions are eliminated so that the shared electric circuit part does not fluctuate when the circuit board is connected or disconnected, and operates at the highest speed in the maximum configuration. Can be set, and the speed of the bus circuit can be increased.

Further, since the input / output circuits are connected to the common electric circuit by the respective connectors, the common electric circuit can be easily replaced when it fails.

Furthermore, since each input / output circuit is formed on the circuit board of the shared electric circuit, the entire structure can be made small.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific example of an input / output circuit in FIG.

FIG. 3 is a circuit diagram showing a specific example of the input / output circuit in FIG.

FIG. 4 is a diagram for explaining characteristic analysis of the embodiment of FIG.

FIG. 5 is a diagram showing measurement data in the state of FIG.

FIG. 6 is a perspective view showing a second embodiment of the present invention.

FIG. 7 is a perspective view showing a third embodiment of the present invention.

FIG. 8 is a perspective view showing an example of a conventional bus circuit device.

9 is a diagram for explaining characteristic analysis of the conventional example of FIG.

FIG. 10 is a diagram showing measurement data in the state of FIG.

[Explanation of symbols]

 1 common electric circuit 2 input / output circuit 3 dedicated circuit 4 connector 5 connector 11 circuit board 21 circuit board 31 circuit board

Claims (3)

[Claims] 1. A bus circuit device having a shared electric circuit which can be commonly used, a plurality of dedicated circuits each having a unique function, and a plurality of input / output circuits for inputting / outputting a signal to / from the shared electric circuit, A bus circuit device characterized in that each of the input / output circuits is provided in advance in the shared electric circuit, and the dedicated circuit and the input / output circuit are detachably connected by respective connectors. 2. The bus circuit device according to claim 1, wherein each input / output circuit is connected to a shared electric circuit by a connector. 3. The bus circuit device according to claim 1, wherein each of the input / output circuits is formed on a circuit board on which a shared electric circuit is formed.