JP2630520B2 - Board hot-swap method - Google Patents

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 live state, and more particularly to a method for preventing a disturbance from occurring on a bus line when inserting or removing a board connected to a bus. It relates to the insertion / extraction method.

2. Description of the Related Art In a control device or the like using a CPU, a method of dividing a circuit into a plurality of substrates and connecting the substrates with a bus is often used. In such a case, if a failure occurs in one of the boards, it is very inefficient to stop the entire apparatus. Therefore, the board is removed in a live state and repaired or replaced. Thereafter, a failure is restored by inserting a non-defective board in a live state again, and a board live insertion / removal method is adopted.

In such a board hot-swap method,
It is desired that no noise is generated on the bus when the board is inserted or removed, and therefore, the normal operation of other operating boards is not hindered.

[0004]

2. Description of the Related Art As an effective method for preventing disturbance on a bus line when a board is inserted or removed in a live state, a conventionally known method is to supply power to a board even when the board is inserted or removed. Is supplied to keep the bus driver on the board in a high impedance state.

To this end, it is necessary to provide a power supply connector for insertion and removal on the board so that the board can be inserted and removed while the power supply is connected via a flexible cable. Conventionally, various proposals have been made for the method of wire insertion / removal.

FIG. 5 shows an example of a conventional board hot-swap method. Reference numeral 11 denotes a board. In a mounted state, a back board side is connected via a bus connection connector (A) 12. And the power supply 5V and the ground GND.

When the board 11 is inserted into and removed from the connector (A) 12, the power supply connector (B)
13 connects the power supply 5V to the ground GND to supply power for operation. Then, the switch 14 is operated to supply a low-level input to the bus driver 15 to maintain the input 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, the bus driver 15 is kept in a high impedance state, so that no noise is generated on the bus when the board 11 is inserted or removed.

FIG. 6 shows another example of the conventional board hot-swap method, in which the same components as those in FIG. It is a voltage detection unit for detecting the presence of the power supply 5V.

In this example, by connecting a connector (B) for supplying power at the time of hot-swap, the voltage detecting section 16 is connected.
Detects the presence of the power supply 5V and generates an output. The bus driver 15 is maintained in a high impedance state by the output of the voltage detection unit 16, and in this state, the substrate 1
1 is inserted and removed.

As described above, in the conventional board hot-swap method,
By connecting the connector (B) or further operating a switch, the bus driver connected to the bus can be brought into a high impedance state. I will not give. Power to be connected to the connector (B) when the board is inserted or removed is supplied from a 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 maintain the bus driver in a high impedance state, a power supply for switch operation or hot-swap operation is required. It is necessary to connect the supply connector mechanically, for example by manual operation.

On the other hand, even if the CPU accesses the board with respect to the board, it cannot usually be recognized from the outside. Therefore, there is a possibility that the bus driver is brought into a high impedance state during the bus access to the board and the bus driver is brought into a high impedance state. However, 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 a board on which hot-swapping is performed, it is necessary to provide a connector for connection in a main power supply unit of the apparatus, or to prepare an external power supply. .

An object of the present invention is to solve such a problem of the prior art, and to prevent a bus driver from being in a high impedance state during a bus access so as to prevent a bus driver from being 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 supplying power to the main power supply unit or preparing an external power supply.

[0015]

FIG. 1 shows the basic configuration of the present invention. The present invention includes a second connector 2 for supplying power to a board, and a plurality of boards connected to a common bus and a power supply connected to the CPU via the first connector 1, respectively. A switch 3 for performing an operation, an interrupt generation circuit 4 for generating an interrupt to the CPU when the switch 3 is operated, and a first connector 1
Are connected to each other to generate a first connector attaching / detaching signal, and a first connector attaching / detaching circuit 5 detecting that the second connector 2 is connected to generate a second connector attaching / detaching signal. A second attach / detach detection circuit 6 that is generated, a write register 7 that holds a hot-swap permission from a CPU that permits hot-swap of the board and generates a hot-swap permission signal, and a first connector attach / detach signal. A bus driver control circuit 9 for setting the bus driver 8 connected to the common bus to a high impedance state based on a predetermined logic based on the respective states of the second connector attaching / detaching signal and the hot-swap permission signal, The CPU stops bus access when a hot-swap permission is issued, thereby enabling the hot-swap of the board.

Further, the present invention provides the above-mentioned invention,
A connector 2 for supplying power from within the board;
A circuit for receiving power supply to the board, and connecting the respective connectors 2 of the board that does not perform insertion and removal and the board that performs insertion and removal via a cable,
Power is supplied from a board that does not perform insertion and removal to a board that performs insertion and removal.

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

[0018]

A second connector is provided on a plurality of boards connected to a common bus and a power supply connected to a CPU via a first connector, respectively, to supply power to the boards. When the switch 3 provided on the board is operated, an interrupt to the CPU is generated, and the hot swapping permission of the board from the CPU based on the interrupt is held in the write register 7 to generate a hot swapping permission signal. , First connector 1
Are detected to generate a first connector attachment / detachment signal, and that the second connector 2 is connected is detected to generate a second connector attachment / detachment signal. And
A bus driver 8 connected to the common bus based on a predetermined logic based on the respective states of the first connector attachment / detachment signal, the second connector attachment / detachment signal, and the hot swapping permission signal.
To a high impedance state.

The CPU stops the bus access when it issues the board hot-swap permission. Therefore, by inserting and removing the board in this state, the bus access is stopped.
The bus driver does not go into a high impedance state, and it is possible to prevent a malfunction of the CPU at the time of hot-swap of the board.

In this case, since the second connector 2 is configured to supply power from the inside of the board and to receive power from the board, the second connector 2 is connected to the board that does not insert or remove the board. Each connector 2
Can be connected via a cable, so that power can be supplied from a board that does not perform insertion and removal to a board that performs insertion and removal.

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

In these cases, generation of the hot-swap permission from the CPU based on the interrupt can be performed based on 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, the substrate 2
1 will be described as a board for performing insertion and removal, and the board 22 will be described as a board for not performing insertion and removal. The board 21 includes a connector 24 for connecting to a bus 23 provided on the backboard side,
And a connector 25 for supplying power during hot-swap.
Although the substrate 22 has the same configuration, FIG. 2 shows only the connector 26 for supplying power during hot-swap.

In FIG. 2, 27 is a connection cable for hot-swap, 28 is a switch for generating an interrupt for the CPU, 29 is an interrupt generating circuit for the CPU, 30
_1, 30 ₂ bus in the substrate 21, 31 is a write register write instruction from the CPU, 32 a bus driver ,, 3
Reference numeral 3 denotes a bus driver control circuit for controlling disabling and enabling of the bus driver 32, and reference numeral 34 denotes a bus driver 32.
, A reference numeral 35 denotes a resistor, 36 denotes an inverter, 37 denotes a resistor, and 38 denotes an inverter.

FIG. 3 explains the operation of the bus driver control circuit, and shows a truth table of a first connector attaching / detaching signal, a second connector attaching / detaching signal, a hot-swap enabling signal and a disable signal. It is shown.

The first connector attaching / detaching signal is
When the connector 25 is inserted, the signal becomes “1” when the connector 25 is inserted.
It becomes “1”. The hot-swap permission signal becomes “1” when the hot-swap permission from the CPU is written into 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 on the board 21 and the connector 26 on the board 22 are connected using a cable 27, and
Power is supplied from the substrate 22 to the substrate 21 side. Thereafter, by operating the switch 28 on the board 21, an interrupt to the CPU is generated from the interrupt generation circuit 29. This interrupt is sent via bus 23 to a C (not shown).
Sent to the PU to notify the CPU that hot-swap is performed on the board 21.

After the bus access is completed, the CPU
Then, a hot-swap permission for the board 21 is issued. This information, in the substrate 21, is written in the write register 31 through the bus 30 _1, 30 _2. Thereafter, the CPU stops the bus access. Such a series of operations of the CPU is performed based on, for example, software of the CPU.

A first connector attaching / detaching signal is input to the bus driver control circuit 32 by the connection of the connector 24, and a second connector attaching / detaching signal is input by the connection of the connectors 25 and 26. Write register 31
When the hot-swap permission signal is generated by writing the hot-swap permission to the bus driver control circuit 33, a disable signal is sent from the bus driver control circuit 33 to the bus driver 32 as shown in (1) in FIG. Is output. As a result, the bus driver 32 enters a high impedance state. At the same time, the indicator light 34 is turned on by the bus driver control circuit 33 to indicate that hot-swapping is possible.

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

When the board 21 is inserted, the connector 24
Are not connected, the connector 25 and the connector 26 are connected by the cable 27, and power is supplied from the board 22. As a result, a second connector attach / detach signal is generated. As shown in (2) in FIG. 3, a disable signal is output from the bus driver control circuit 33 to the bus driver 32, and the bus driver 32 In a high impedance state.

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

When other devices or the like that need to be reset are included in the board at the time of hot-swap, these devices are reset simultaneously by using the above-described disable signal to the bus driver. can do.

FIG. 4 shows an application example of the present invention. A board 41 on which a CPU 40 is mounted and a plurality of boards 42, 43, 44 on which peripheral circuits are mounted are connected via a common bus 45. And interconnected systems are shown.

In the system shown in FIG. 4, for example, when the board 42 is hot-plugged, the hot-swap connection cable 46 is used to connect the board 42 to the board 43 adjacent thereto, for example.
By performing the operation according to the procedure described in the embodiment of FIG. 2 in a state where the connection is established, the board 42 can be inserted and removed without any hindrance to the bus access of the CPU 40.

By providing the connectors for connecting the hot-swap connection cables 46 on all of the boards 41 to 44 in the same manner, no matter which board is to be inserted or removed, the hot-plug between the adjacent board is required. By connecting the connecting / disconnecting connection cable 46, hot-swapping 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 connection cable for hot-swap to the main power supply unit of the apparatus, or to provide an external power supply for that purpose.

[0037]

As described above, according to the present invention, when a plurality of boards are detachably connected to a bus, when a board is hot-swapped, the timing for setting the bus driver to high impedance is determined by the bus access of the CPU. It is possible to prevent malfunction of the CPU due to hot swapping of the board because it is not the case, and also to supply power from the board that is not inserted or removed, so that hot plugging can be performed only by preparing a connection cable Becomes possible.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a configuration of one 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 the conventional board hot-swap method.

[Explanation of symbols]

 DESCRIPTION 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)

(57) [Claims] 1. A plurality of boards connected to a common bus and a power supply connected to a CPU via a first connector (1), respectively, a second connector (2) for supplying power to the boards, A switch (3) for performing an operation for hot-swapping the board, an interrupt generation circuit (4) for generating an interrupt to the CPU when the switch (3) is operated, and the first connector (1) connected A first connector detection signal (5) for detecting that the second connector (2) is connected, and a second connector connection signal for detecting that the second connector (2) is connected. A write register (7) for holding a hot-swap permission from a CPU permitting hot-swap of the board and generating a hot-swap permission signal; A first connector attaching / detaching signal; A bus driver control circuit (9) for setting a bus driver (8) connected to the common bus to high impedance based on a predetermined logic based on a state of each of the connector attaching / detaching signal and the hot-swap permission signal; A board hot-swap method, wherein the CPU stops bus access when the hot-swap permission is issued, thereby enabling the board to be hot-swapped. 2. The second connector (2) has a circuit for supplying power from inside the board and a circuit for receiving power from the board, and performs insertion and removal with a board that does not perform insertion and removal. 2. The board hot-swap method according to claim 1, wherein power is supplied to the board to be inserted and removed from the board which is not inserted and removed by connecting respective connectors (2) to the board via a cable. . 3. The generation of a hot-swap permission from the CPU based on an interrupt from the interrupt generation circuit (4) is performed by the C
3. The method according to claim 1, wherein the control is performed based on software control in the PU.