JPH05127777A - Substrate insertion and extraction in hot-line state - Google Patents

Abstract

PURPOSE:To prevent turbulence from being generated on a bus line when a bus-connected substrate is inserted or extracted. CONSTITUTION:The substrate which is connected to the bus of a CPU and a power source through a 1st connector 1 is equipped with a 2nd connector 2 for supplying electric power, a switch 3 which is operated at the time of insertion or extraction of the substrate in hot-line state, an interruption initiating circuit 4 which initiates an interruption to the CPU when the switch 3 is operated, a 1st attachment/detachment detecting circuit 5 which generates a 1st connector attachment/detachment signal when the 1st connector 1 is connected, a 2nd attachment/detachment detecting circuit 6 which generates a 2nd connector attachment/detachment signal when the 2nd connector 2 is connected, a write register 7 which holds the permission for insertion or extraction of the CPU in the hot-line state and generates insertion/extraction permission signal, and a bus driver control circuit 9 which holds a bus driver 8 high in impedance with the 1st connector insertion/extraction signal, 2nd connector insertion/ extraction signal, and insertion/extraction in hot-line state permission signal; when the CPU issues the permission for insertion or extraction in hot-line state, bus access is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inserting and removing a board in a hot line state, and more particularly, a method for preventing a disturbance from occurring on a bus line when inserting and removing a board connected to a bus. It relates to the insertion / removal method.

In a control device or the like using a CPU, a method is often used in which the circuit is divided into a plurality of boards and the boards are connected by a bus. In such a case, if one of the substrates fails, it is very inefficient to stop the entire device for that reason. Therefore, the substrate is pulled out in a live state and repaired or replaced. After that, a hot-plugging and unplugging method of the board is adopted in which a good board is inserted again in a hot-line state to restore the fault.

In such a hot-plugging method for the substrate,
It is desired that noise does not occur on the bus when the board is inserted / pulled out, so that normal operation of the board during other operations is not hindered.

[0004]

2. Description of the Related Art When inserting or removing a board in a hot line state, a method known to be effective in order to prevent disturbance on the bus line is that a power supply is applied to the board during insertion and removal. Is to maintain the bus driver on the substrate in a high impedance state.

To this end, it is necessary to provide a connector for power supply at the time of insertion / removal on the board so that the board can be inserted / removed while the power source is connected via a flexible cable. Various proposals have heretofore been made regarding the wire insertion / extraction method.

FIG. 5 shows an example of a conventional hot-swap method for a board, in which 11 is a board, and in a mounted state, a backboard side is provided via a connector (A) 12 for bus connection. And the power supply 5V and the ground GND.

When the board 11 is inserted into or removed from the connector (A) 12, the connector (B) for supplying power during hot-line insertion and removal.
By connecting 13, the power supply 5V and the ground GND are connected to supply power for operation. Then, the switch 14 is operated to give a low level input to the bus driver 15 to hold it in a high impedance state, and the board 11 is inserted and removed in this state. Although the bus driver 15 is connected to the bus via the connector (A) 12, it is held in a high impedance state, and therefore noise is not generated on the bus when the board 11 is inserted and removed.

FIG. 6 shows another example of the conventional board hot-swap system, in which the same parts as those in FIG. 5 are designated by the same reference numerals, and 16 is the one when the connector (B) 13 is connected, It is a voltage detection unit for detecting the presence of the power supply 5V.

In this example, the voltage detector 16 is connected by connecting the connector (B) for supplying power during hot plugging and unplugging.
Detects the presence of a 5V power supply and produces an output. The bus driver 15 is held in a high-impedance state by the output of the voltage detection unit 16, so that in this state the substrate 1
Insert and remove 1.

As described above, in the conventional hot-plugging method for the substrate,
The bus driver connected to the bus can be brought to a high impedance state by connecting the connector (B) or further operating the switch. Therefore, if the board is inserted and removed in this state, the bus is disturbed. Never give. The power to be connected to the connector (B) when the board is inserted / removed is supplied from the main power supply unit of the device or an external power supply device.

[0011]

In the conventional board hot-swap method as shown in FIGS. 5 and 6, in order to keep the bus driver in a high impedance state, a switch operation or a power supply at hot-swap is used. It is necessary to connect the supply connector mechanically, for example by manual operation.

On the other hand, even if the CPU makes a bus access to the board, it is usually impossible to recognize this from the outside. Therefore, there is a possibility that the bus driver is put into the high-impedance state while being inserted / removed during the bus access to the board, but in such a case, there is a problem that the normal operation of the CPU cannot be guaranteed.

Further, in order to supply power to the board for hot-plugging and unplugging, it is necessary to provide a connector for connection in the main power source of the apparatus, or to prepare an external power source for that purpose. ..

The present invention is intended to solve such a problem of the prior art, and prevents the bus driver from being in a high impedance state during bus access so that the board is hot-swapped. It is an object of the present invention to prevent malfunction of the CPU, and to eliminate the need for providing a connector for connecting to the main power supply unit for power supply or preparing an external power supply.

[0015]

FIG. 1 shows the basic configuration of the present invention. The present invention relates to a plurality of boards which are connected to a common bus connected to a CPU and a power supply through a first connector 1, respectively, and a second connector 2 which supplies power to the boards and a hot plug of the boards. A switch 3 for operating, an interrupt generating circuit 4 for generating an interrupt to the CPU when the switch 3 is operated, and a first connector 1
Is detected to generate a first connector attachment / detachment signal and a second connector 2 is detected to detect a second connector attachment / detachment signal. A second connection / disconnection detection circuit 6 that is generated; a write register 7 that generates a hot-swap permission signal by holding a hot-swap permission from a CPU that permits hot-swap of a board; A bus driver control circuit 9 that puts the bus driver 8 connected to the common bus into a high-impedance state based on a predetermined logic from the respective states of the second connector attachment / detachment signal and the hot-swap permission signal. When the hot-swap permission is issued, the CPU stops the bus access so that the board can be hot-swapped.

The present invention also provides the second invention in the above-mentioned invention.
Connector 2 of the circuit, which supplies power from inside the board,
A circuit for receiving power supply to the board, and connecting the respective connectors 2 of the board not to be inserted and removed and the board to be inserted and removed via a cable,
The power is supplied from the board which is not inserted and removed to the board which is inserted and removed.

Further, according to the present invention, in these cases, the generation of the hot-swap permission from the CPU based on the interrupt from the interrupt generation circuit 4 is performed based on the software control in the CPU.

[0018]

The second connector 2 is provided on each of a plurality of boards which are connected to the common bus connected to the CPU and the power supply via the first connector 1, and the power is supplied to the boards. When the switch 3 provided on the board is operated, an interrupt is generated to the CPU, the hot-plugging permission of the board from the CPU based on this interrupt is held in the write register 7, and a hot-plugging permission signal is generated. , The first connector 1
Is detected to generate a first connector attachment / detachment signal, and the second connector 2 is detected to be connected to generate a second connector attachment / detachment signal. And
A bus driver 8 connected to the common bus based on a predetermined logic from the respective states of the first connector attachment / detachment signal, the second connector attachment / detachment signal, and the hot-swap permission signal.
To high impedance state.

When the CPU issues a hot-line insertion / removal permission of the board, the bus access is stopped. Therefore, by inserting / removing the board in this state, during the bus access,
The bus driver does not enter the high impedance state, and it is possible to prevent the malfunction of the CPU when the board is hot-swapped.

In this case, since the second connector 2 is configured to supply power from the inside of the board and receive power from the board, the board not to be inserted and removed and the board to be inserted and removed. Each connector 2
Is connected via a cable, it is possible to supply power from a board that is not inserted or removed to a board that is inserted or removed.

Therefore, according to the present invention, there is no need to provide a connector for connecting to the main power source for supplying power or to prepare an external power source.

In these cases, it is possible to generate the hot-swap permission from the CPU based on the interrupt based on the software control in the CPU.

[0023]

FIG. 2 shows the structure of an embodiment of the present invention, in which equivalent substrates 21 and 22 are shown, but the number of substrates is arbitrary. In the following, substrate 2
1 will be described as a substrate that is inserted and removed, and the substrate 22 will be described as a substrate that is not inserted and removed. The board 21 includes a connector 24 for connecting to a bus 23 provided on the backboard side,
It has a connector 25 for supplying power during hot plugging and unplugging.
The board 22 has the same structure, but in FIG. 2, only the connector 26 for supplying power during hot-plugging and unplugging is shown.

In FIG. 2, 27 is a connection cable for hot-line insertion / removal, 28 is a switch for interrupt generation operation for the CPU, 29 is an interrupt generation circuit for the CPU, and 30 is a circuit.
_1, 30 ₂ are buses in the substrate 21, 31 is a write register for writing instructions from the CPU, 32 is a bus driver, 3
Reference numeral 3 is a bus driver control circuit for controlling disabling and enabling of the bus driver 32, and 34 is a bus driver 32.
, 35 is a resistor, 36 is an inverter, 37 is a resistor, and 38 is an inverter.

FIG. 3 illustrates the operation of the bus driver control circuit, and is a truth table of the first connector attachment / detachment signal, the second connector attachment / detachment signal, the hot-swap permission signal, and the disable signal. Is shown.

The first connector attachment / detachment signal is the connector 2
When the connector 25 is inserted, it becomes "1", and when the connector 25 is inserted,
It becomes "1". Also, the hot-swap permission signal becomes “1” when the hot-swap permission from the CPU is written in the write register 31. When the disable signal of the bus driver is disabled (high impedance state),
It becomes "1" and becomes "0" when enabled.

When the board 21 is to be pulled out, the connector 25 of the board 21 and the connector 26 of the board 22 are connected using a cable 27,
Power is supplied from the substrate 22 to the substrate 21 side. After that, by operating the switch 28 on the substrate 21, the interrupt generation circuit 29 generates an interrupt to the CPU. This interrupt is sent via the bus 23 to C (not shown).
It is sent to the PU to notify the CPU that hot plugging and unplugging will be performed on the board 21.

After the bus access is completed, the CPU operates the bus 23
After that, the hot-swap permission for the board 21 is issued. This information is written in the write register 31 on the substrate 21 via the buses 30 _{1 and} 30 ₂ . The CPU then stops bus access. Such a series of operations of the CPU is performed based on, for example, software included in the CPU.

To the bus driver control circuit 32, the first connector attachment / detachment signal is input by connecting the connector 24, and the second connector attachment / detachment signal is input by connecting the connectors 25 and 26. Write register 31
When the hot-swap permission signal is generated because the hot-swap permission is written in, the bus driver control circuit 33 sends a disable signal to the bus driver 32, as indicated by (1) in FIG. Is output. As a result, the bus driver 32 enters a high impedance state. At the same time, the bus driver control circuit 33 turns on the indicator lamp 34 to indicate that the hot-plugging / unplugging is ready.

In this state, if the board 21 is pulled out from the connector 24 while the cable 27 is still connected, the power supply from the connector 24 is stopped, but since the power is supplied from the connector 25, the bus driver 32 goes high. The substrate 21 can be removed while maintaining the impedance state.

When inserting the board 21, the connector 24
In a state in which the connector 25 and the connector 26 are not connected, a cable 27 is connected between the connector 25 and the connector 26 to supply power from the substrate 22. As a result, the second connector attachment / detachment signal is generated, so that the bus driver control circuit 33 outputs a disable signal to the bus driver 32, as shown in (2) of FIG. , High impedance state.

By connecting the connector 24 while connecting the cable 27, the board 21 can be inserted while keeping the bus driver 32 in a high impedance state. By connecting the connector 24,
Since the first connector attachment / detachment signal is inputted, as shown in (3) in FIG. 3, the bus driver control circuit 3
From 3, the output of the disable signal to the bus driver 32 is stopped, the bus driver 32 is enabled, and becomes the operable state.

When the board includes other devices that need to be reset during hot-plugging and unplugging, these devices are simultaneously reset using the disable signal for the bus driver. can do.

FIG. 4 shows an application example of the present invention. A substrate 41 having a CPU 40 mounted thereon and a plurality of substrates 42, 43, 44 having peripheral circuits mounted thereon are connected via a common bus 45. Systems interconnected with each other are shown.

In the system shown in FIG. 4, for example, when the board 42 is hot-swapped, the board 43 is adjacent to the board 42 by the hot-swap connection cable 46.
By performing the operation according to the procedure described in the embodiment of FIG. 2 in a state in which and are connected, it is possible to insert and remove the substrate 42 without any trouble in the bus access of the CPU 40.

It should be noted that by providing connectors for connecting the hot-swap connection cable 46 to all of the substrates 41 to 44 in the same manner, no matter which of the substrates is to be inserted or removed, the live line between the adjacent substrates will be used. By connecting the connecting / disconnecting connection cable 46, the hot plugging / unplugging of the board can be performed by the same operation. Therefore, according to the present invention, it is not necessary to provide a connector for connecting the hot-swap connection cable to the main power supply unit of the apparatus, or to prepare an external power supply for that purpose.

[0037]

As described above, according to the present invention, in a plurality of boards that are removably connected to a bus, when a board is hot-plugged and unplugged, the timing at which the bus driver is set to high impedance is the bus access of the CPU. It is possible to prevent a malfunction of the CPU due to hot plugging and unplugging of the board, except when it is time to use, and since power is supplied from the board that is not plugged or unplugged, hot plugging and unplugging can be performed simply by preparing a cable for connection. Is possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a principle configuration of the present invention.

FIG. 2 is a diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 3 is a diagram illustrating an operation of a bus driver control circuit.

FIG. 4 is a diagram showing an application example of the present invention.

FIG. 5 is a diagram showing an example of a conventional board hot-swap method.

FIG. 6 is a diagram showing another example of a conventional board hot-swap method.

[Explanation of symbols]

 1 1st connector 2 2nd connector 3 switch 4 interrupt generation circuit 5 1st attachment / detachment detection circuit 6 2nd attachment / detachment detection circuit 7 write register 8 bus driver 9 bus driver control circuit

Claims (3)

[Claims] 1. A plurality of boards respectively connected to a common bus connected to a CPU and a power supply via a first connector (1), and a second connector (2) for supplying power to the boards, A switch (3) that is operated when the board is hot-swapped, an interrupt generation circuit (4) that generates an interrupt to the CPU when the switch (3) is operated, and the first connector (1) are connected. A second connector attachment / detachment signal by detecting that the first connector attachment / detachment detection circuit (5) that detects that the second connector (2) is connected A second attach / detach detection circuit (6) for generating a hot-swap enable / disable signal from the CPU for permitting hot-swap of the board, and a write register (7) for generating a hot-swap enable / disable signal. The first connector attachment / detachment signal and the second A bus driver control circuit (9) for setting the bus driver (8) connected to the common bus to high impedance based on a predetermined logic based on the respective states of the connector attachment / detachment signal and the hot-swap enable / disable signal; A hot-swap board system, wherein when the hot-swap permission is issued, the CPU stops bus access so that the board can be hot-swapped. 2. The second connector (2) has a circuit for supplying power from inside the board and a circuit for receiving power supply to the board, and performs insertion and removal with and without a board. The hot-plugging and unplugging method for the board according to claim 1, characterized in that power is supplied to the board to be inserted and removed from the board not to be inserted and removed by connecting the respective connectors (2) to the board via a cable. .. 3. The generation of hot-swap permission from the CPU based on the interrupt from the interrupt generation circuit (4)
The hot-swap method for a substrate according to claim 1 or 2, wherein the hot-swap method is performed based on software control in the PU.