JPH0816732A - Connection method of hot-pluggable motherboard bus - Google Patents

Abstract

PURPOSE: To provide a method for connection/disconnection for preventing damage on a mother board at the time of connection/disconnection between a mother board and an IC card. CONSTITUTION: This method for connecting an IC card 1 with a mother board 2 includes the connection of a ground bus 28 at first, then a power bus 27, and finally a general-purpose. signal bus 26. When the power bus 27 is connected, first constant currents are allowed to flow, next a prescribed time passes for averaging the voltages of the IC card 1 and the mother board 2, and then full currents are allowed to flow. On the other hand, a method for disconnecting the IC card 1 from the mother board 2 first includes the disconnection of the general-purpose signal bus 26, then the power bus 27, and finally the ground bus 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connector circuit for connecting an integrated circuit card (IC card) to a mother board. This connection is hotpluggable
It is done in a system and there is no need to deactivate the motherboard bus when the card is connected to the motherboard.

[0002]

2. Description of the Related Art Conventionally, when a new IC card is connected to a motherboard bus, this motherboard must be deactivated, so that another IC card that was previously connected can be used for this bus. There wasn't.
Deactivation was necessary because a new card could add a noise signal to the bus during insertion. Such a noise signal negatively affects the use of the bus by the previously inserted IC card. For example, data conducted along a motherboard using an existing IC card could be lost during the insertion of a new IC card.

Hot-pluggable connections have been developed between IC cards and motherboards that do not require the motherboard bus to be deactivated during the insertion of a new card. In these conventional devices, the edge connector is arranged on the IC card that connects to the motherboard. When connecting this IC card to the corresponding receptacle on the motherboard, I
A power connection to electrical components on C and a general purpose signal connection (eg, for data and address) are made during the same connection. In order to ensure stable operation of the bus to which the card is connected, it is necessary to ensure that power and general purpose signal connections are made in a certain order. For example, it is better to make power connection before general signal connection.

US Pat. No. 5,210,855 discloses that a ground connection is first made and then a power connection is made.
Finally, the connection sequence in which the universal signal connection is made is described.

[0005]

However, there are problems with these devices. In particular, power is applied to the card as soon as a power connection is made between the IC card and the motherboard bus. This causes a short circuit through the motherboard bus. This causes the following problems.
First, physical damage to the connector can occur, for example, the connector can be damaged by a temporary short circuit. Second, short circuits on the power bus due to electromagnetic interference can cause disturbances on the signal lines on the motherboard bus. Third, the stable voltage level can go out of range, thus seriously affecting all other IC cards connected to the motherboard bus.

Another problem that exists with the conventional "hot pluggable" devices described above is that if the card containing the active device is physically removed from the motherboard, the active device present on the connector will It is to cause destruction in the bus.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems existing in the prior art. Another object of the present invention is to provide controlled power application from the motherboard bus to the IC card. The current flow is limited to a safe value until the voltage level between the motherboard bus and the IC card is even.

Yet another object of the present invention is to provide a controlled disconnection of various connections between an IC card and a motherboard when the IC card is physically removed from the motherboard. Once the connector is completely disconnected, only then is the IC card physically removed from the motherboard bus. Therefore, it is possible to prevent the bus from being destroyed.

According to the present invention, in a method of connecting an IC card to a motherboard, (a) it is detected that the IC card is inserted in a connector arranged on the motherboard, and (b) the power of the IC card is detected. Connecting the power bus of the motherboard to the bus, and (c) connecting the general-purpose signal bus of the motherboard to the general-purpose signal bus of the IC card. The step (b) includes (b1) the motherboard Only a low current is allowed to flow between the power bus and the power bus of the IC card, and (b2) a predetermined amount corresponding to the time required for the voltage levels between the mother board and the IC card to become even. (B3) providing a method for allowing all current to flow between the power bus of the motherboard and the power bus of the IC card.

A connector is provided on the motherboard for connecting the ground, power and general signal connections of the IC card to the corresponding motherboard buses. When connecting the IC card to the motherboard, the connections are made in the following order. First, the ground connection is made, then the power connection,
Finally, the general data connection is made. When a power connection is made, the current flow is limited under program control, for example by a variable resistance circuit, so that a safe amount of current flows through the power connection between the IC card and the motherboard power bus. Then, the motherboard bus and IC
The current is allowed to reach a maximum steady state value under program control after a predetermined time period during which the voltage level between the cards becomes uniform.

When the IC card is removed from the motherboard, the connection between the IC card and the motherboard bus is IC
When the cards are connected to the motherboard they are released in the opposite order in which they engage. That is, under program control, first the general purpose signal connection is released, then the power connection is released, and finally the ground connection.

[0012]

The invention will be explained by the following examples with reference to the accompanying drawings. FIG. 1 shows a basic circuit configuration according to the present invention. The IC card 1 is connected to the motherboard 2 via a connection circuit 21 arranged on the motherboard 2. The ground bus of the IC card 1 is connected to the ground bus 28 of the mother board 2 while inserting the card into the connector 21. The controller 25 includes a connector 21 and a general-purpose signal bus 26.
It controls the switches 22 and 23, which are arranged respectively between the power and the power bus 27, so that these switches close as follows. For example, when it is detected that the IC card 1 is physically inserted in the connector 21 by monitoring the power supply current (see step S1 in FIG. 2).
The controller 25 closes the switch 23 (steps S2 to S4 described in detail below) to connect the motherboard power bus 27 to the IC card 1. Finally, the controller 25 closes the switch 22 (step S5) and connects the general-purpose signal bus 26 of the motherboard to the IC card 1.

The switch 23 has a form in which the impedance can be set to a constant value for a predetermined time under the control of the controller 25. The controller controls the impedance of the switch 23 so that the initial current is safe and limited to a low value (step S2). Then, after a lapse of a predetermined time (step S3) (however, this time depends on the time required for the voltage levels between the mother board 2 and the IC card 1 to become equal), the controller 25 controls the switch 23. The impedance is reduced and the maximum steady-state current for proper operation of the IC card 1 is passed through the card 1 (step S4).

Thus, physical damage to the connector due to arcing on the connector due to the initial inrush current into the card is prevented by using the controlled current switch as described above. Further, disturbance to the signal line 26 on the motherboard due to electromagnetic interference is prevented. Moreover, fluctuations in the stable voltage level on the motherboard 2 are prevented. In addition, the controller 25 is installed by the user on the motherboard 2
When it is desired to physically remove the IC card 1 (see step S6 in FIG. 3), the switches 22 and 23 are controlled by the following method. These switches are in a certain order,
In particular, when the IC cards are initially connected to the motherboard connector 21, they are opened in the order opposite to the order in which they are closed. More specifically, first the general purpose signal bus switch 22 is opened (step S7) and then the power bus switch 23 is opened (step S8). Then, the motherboard connector 21
Then, an instruction is given to the user indicating that the card 1 may be physically disconnected (step S9). The ground connection is disconnected when the card is physically removed by the user.

It is important that these switches are opened before the IC card 1 is physically removed from the connector 21. In particular, if these switches are opened first, mechanical contact bounce on the signal line (contact bounce, CONTACT BOUNCE) can be prevented. There are two ways to implement such disconnection of the connecting line. First, software control techniques are used in which the registers are included in the controller 25. When the user wants to physically remove the IC card, a predetermined value is written in this register. Under software control, the contents of registers are constantly checked to determine if their contents are equal to a predetermined value. When it is determined that the register contents are equal to the predetermined value, the switches 22 and 23 are opened. After these switches are opened, the user is instructed that the IC card 1 may be physically removed from the motherboard connector 21 by, for example, a CRT or an indicator light.

The second method is a mechanical technique in which a sensing element such as an optical sensor or a pressure sensor senses that the access cover (which covers the IC card 1) has been removed. When this access cover is removed, it is obvious that the user may be in the process of removing the IC card 1 from the motherboard connector 21. The switch is opened as described above when the sensing element senses that the access cover has been removed.

The method of connecting the IC card to the motherboard involves first connecting the ground bus, then the power bus, and finally the general purpose signal bus. When the power bus is connected, initially a stall current is made to flow, then a predetermined time has passed to equalize the voltages of the IC card and the mother board, and then all the current is made to flow. The method of disconnecting the IC card from the motherboard is to first use the general-purpose signal bus, then the power bus,
Finally, it involves disconnecting the ground bus.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a basic circuit configuration according to the present invention.

FIG. 2 is a flowchart showing a connection procedure for connecting an IC card to a motherboard according to the present invention.

FIG. 3 is a flowchart showing a disconnection procedure for disconnecting an IC card from a motherboard according to the present invention.

[Explanation of symbols]

 1 IC Card 2 Motherboard 21 Connector 22, 23 Switch 25 Controller 26 General-purpose Signal Bus 27 Power Bus 28 Ground Bus

Claims (2)

[Claims] 1. A method of connecting an IC card to a mother board, comprising: (a) detecting that the IC card is inserted in a connector arranged on the mother board; and (b) connecting to a power bus of the IC card. Connecting the power bus of the motherboard, and (c) connecting the general-purpose signal bus of the motherboard to the general-purpose signal bus of the IC card. The step (b) includes (b1) the power bus of the motherboard. Only a low current is allowed to flow between the IC card and the power bus of the IC card, and (b2) a predetermined time corresponding to the time required to equalize the voltage levels between the motherboard and the IC card. Wait, (b3) a method of allowing all current to flow between the power bus of the motherboard and the power bus of the IC card. 2. A method of disconnecting an IC card from a mother board, comprising:
Deciding to remove the C card, (b) disconnecting the general purpose signal bus of the motherboard from the general purpose signal bus of the IC card, and (c) disconnecting the power bus of the motherboard from the power bus of the IC card. Disconnecting, and (d) a method comprising the steps of instructing the user that the card may be physically disconnected from the motherboard.