JP3421019B2 - Data transmission 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 data transmission method and, for example, in a system in which two circuit parts are connected via a connector, when both circuit parts are connected, this connection is performed. It is suitable for application to the case where the other circuit unit is notified from the side.

[0002]

2. Description of the Related Art In recent years, in electronic equipment such as communication equipment, with the expansion of functions, circuits are often divided for each function and distributed over a plurality of printed wiring boards.

In such a configuration, it is necessary to electrically connect the printed wiring boards in order to exchange data between the printed wiring boards.

As a connection method in this case, there is a method of directly connecting each printed wiring board through a connector.

However, in such a method, for example, when the number of printed wiring boards increases, the number of connecting connectors increases, so that the connection structure becomes complicated.

Therefore, in such a case, generally, a printed wiring board (hereinafter referred to as a "control package") having a connection control section for connecting a plurality of printed wiring boards to each other is prepared, and this control package is provided. In many cases, ordinary printed wiring boards (hereinafter referred to as "normal packages") are used to connect to each other.

According to this structure, the number of connecting connectors can be reduced, so that the connecting structure can be simplified.

By the way, in the case of a structure in which a plurality of normal packages are connected to each other via the control package as described above, the connection control unit of the control package needs to recognize that the normal packages are connected.

If this recognition is not made, this is because the connection control unit performs the access processing of the normal package even if the normal package is not connected, and as a result, for example, the connection control unit fails. Because there is.

As a method of this recognition, there is a method in which the connection control unit regularly monitors the connection of the packages.

However, in such a method, when the number of normal packages connected to the control package increases, the load on the connection control unit increases.

Therefore, in general, the normal package is provided with a connection notification function, and the normal package notifies the connection control section of the connection.

According to such a configuration, the connection control unit does not need to regularly monitor the connection of the normal package, so that the burden is reduced.

Here, the configuration of a conventional connection notification device will be described with reference to FIG. Note that FIG. 2 shows a state in which one normal package is connected to the control package.

In the figure, 10 is a normal package, and 20 is a control package to which the normal package 10 is connected. Reference numeral 30 is a backboard that is interposed between the normal package 10 and the control package 20.
41 and 42 are the normal package 10 and the backboard 30.
Is a connector for connecting. Reference numerals 51 and 52 are connectors for connecting the control package 20 and the backboard 30.

In the normal package 10, reference numeral 11 is a connection notification line used to generate and notify the connection notification signal S1 for notifying the connection control unit 21 of the control package 20 of the connection of the normal package 10. Reference numeral 12 is a data transmission unit for supplying the internal data D1 of the normal package 10 to the control package 20. Reference numeral 13 denotes a reset signal generation unit that generates a reset signal S2 for setting a circuit mounted on the normal package 10, for example, a memory register to an initial state.

In the control package 20, 21
Is a normal package 1 connected to the control package 20.
0 is a connection control unit that connects 0 and other packages (not shown) to each other. The connection control unit 21 is composed of, for example, a central processing unit (CPU).

The reset signal S2 output from the reset signal generator 13 is also used as a control signal for inhibiting the data transmission operation of the data transmitter 12.

The operation of the above structure will be described with reference to the timing chart of FIG. First, the connection notification operation that the present invention focuses on will be described.

When the normal package 10 is connected to the control package 20 via the backboard 30 (timing t1), the connection notification line 11 receives the connection notification signal S1 of high level "H" as shown in FIG. It is generated and supplied to the connection control unit 21. As a result, the connection control unit 21
It can be recognized that the normal package 10 is connected to the control package 20.

The above is the connection notification operation. Next, for reference, an operation of supplying the internal data D1 of the normal package 10 to the connection control unit 21 will be described.

When the connection notification signal S1 is supplied to the connection control unit 21, the data transmission unit 12 is sent from the connection control unit 21.
Is supplied with the access signal S3 for fetching the data D1. In FIG. 3, the arrow indicates this access signal S.
3 shows the access timing of No. 3.

However, when the normal package 10 is connected to the backboard 30, the power supply voltage is supplied from the external power source to the circuit mounted on the normal package 10. As a result, the reset signal generator 13 outputs the low-level “L” reset signal S2 as shown in FIG. As a result, a startup process for setting the on-board circuit to the initial state is executed. Further, the data transmission operation in the data transmission unit 12 is prohibited. So in this case,
Even if the access signal S3 is supplied, the data D1 is not supplied to the connection control unit 21.

After that, when the reset signal S2 disappears (timing t2), the prohibition state of the data transmission operation of the data transmission section 12 is released. As a result, the data D1 is transmitted from the data transmission unit 12 in synchronization with the access signal S3 output from the connection control unit 21. In Figure 3,
The data D1 sent from the data sending unit 12 is changed to D2.
Show as.

Data D1 supplied to the connection controller 21
(D2) is supplied to, for example, another normal package (not shown). As a result, the normal package 10 and another normal package (not shown) are connected to each other.

The reason why the sending of the data D1 is blocked when the normal package 10 is started is to prevent the abnormal data D1 (D2) from being taken into the connection control section 21, for example.

That is, when the normal package 10 is connected, the connectors 41 and 42 are temporarily in an intermittent contact state, so that the data D1 held in the memory register or the like fluctuates. Therefore, when the connection of the normal package 10 is completed, the reset signal S2 is generated and the data D1 is generated.
Is reset to the initial value.

However, in this case, it takes some time for the data D1 to stabilize. Therefore, during the generation period of the reset signal S2, the transmission of the data D1 is prohibited, and the transmission of the data D1 is started after the reset signal S2 disappears, so that the connection control unit 21 receives the stable data D1 (D2).
Is to be supplied.

This state is shown in FIG. In the figure, T1
Indicates an unstable period of the data D1 due to intermittent contact of the connectors 31 and 32, and T2 indicates an unstable period due to execution of the startup process.

[0030]

As described above, conventionally, when the normal package 10 is connected to the backboard 30, this connection is notified to the connection notifying unit 21.

However, such a configuration has a problem that the connection control unit 21 may malfunction when the normal package 10 is connected.

That is, when the normal package 10 is connected to the backboard 30, the normal package 10 executes the start-up process and blocks the transmission of the data D1.
As a result, the connection control unit 21 cannot obtain a response to the access signal S2, and therefore, for example, it is determined that an abnormality has occurred in the normal package 10 and malfunctions.

The present invention has been made to cope with such a situation, and prevents the connection control section 21 from malfunctioning due to no response to an access signal when the normal package 10 is connected. It is an object of the present invention to provide a connection notification device capable of performing the above.

[0034]

In order to achieve the above object, according to a first aspect of the invention, when data is transmitted between a first circuit portion and a second circuit portion connected to the first circuit portion, the first circuit portion is connected to the first circuit portion. In the data transmission method of outputting a signal for instructing a connection state between the second circuit section and the second circuit section and transmitting the data, until the first circuit section becomes ready to transmit the data,
When a signal indicating that the first circuit unit is not connected is output to the second circuit unit and the first circuit unit is ready to transmit data, the second circuit unit and the second circuit unit are connected to each other. In order to start the data transmission with the first circuit unit, the data transmission is performed after outputting a signal instructing that the first circuit unit is connected to the second circuit unit. To do.

Further, in the second invention, when data is transmitted between the peripheral device and the computer connected thereto, a signal for instructing the connection state between the peripheral device and the computer is outputted to transmit the data. In the data transmission method, the peripheral device outputs a signal instructing that the peripheral device is not connected until the peripheral device is ready to transmit data, and the peripheral device is in a state in which data can be transmitted. Then, in order to start transmission of the computer, data is transmitted after outputting a signal instructing that the peripheral device is connected to the computer.

Therefore, for example, even if the normal package (corresponding to the first circuit unit or the peripheral device) is connected to the backboard, the connection notification (the second circuit) is immediately issued.
Output of a signal instructing that the first circuit unit is connected to the circuit unit of, or output of a signal instructing that the peripheral device is connected to the computer) is not performed, It is possible to adopt a configuration in which the connection notification is issued after the start-up process of the normal package is completed.

According to this, the access of the normal package by the connection control unit (corresponding to the second circuit unit or the computer) is started after the normal package can send data. It As a result, it is possible to prevent the connection control unit from malfunctioning due to no response to the access signal.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. Note that, in FIG. 1, portions that perform the same functions as those in FIG. 2 described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, when the normal package 10 is connected to the backboard 20, the connection notification signal S1 is sent.
Is similar to the case of FIG.

However, in FIG. 2, this connection notification signal S1
Is immediately supplied to the connection control unit 21, whereas in this embodiment, the supply is blocked until the startup process of the normal package 10 is completed.
Both are different.

That is, in FIG. 1, reference numeral 14 denotes a connection notification signal blocking unit which blocks the supply of the connection notification signal S1 to the connection control unit 21 until the startup process of the normal package 10 is completed. This connection notification signal blocking unit 14
Reset signal S output from the reset signal generator 13
2 is used to block the supply of the connection notification signal S1.

FIG. 5 is a diagram showing an example of a specific configuration of the connection notification signal blocking unit 14.

As shown in the figure, the connection notification signal blocking unit 14
It is configured by a 2-input AND circuit 141. The connection notification signal S is applied to one input terminal of the AND circuit 141.
1 is supplied to the other input terminal of the reset signal S2
Is supplied.

According to such a configuration, the reset signal S
Since 2 is a low level “L” signal, the gate of the AND circuit 141 is closed while the reset signal S2 is output, and the gate is opened when the reset signal S2 disappears. As a result, the connection notification signal S1 is blocked from being supplied to the connection control unit 21 while the reset signal S2 is being output, and is supplied to the connection control unit 21 when the reset signal S2 disappears.

FIG. 6 is a diagram showing an example of a specific configuration of the reset signal generator 13.

In the figure, 131 is a time constant circuit, which is composed of, for example, a variable resistor 1a and a capacitor 2a. Reference numeral 132 is an inverter that outputs the reset signal S2 by shaping the voltage across the variable resistor 1a. 133 is a power supply terminal to which the power supply voltage Vcc is supplied.

In such a structure, the package 10 is usually connected to the backboard 30 and the power supply terminal 133 is used.
When the power source voltage Vcc is supplied to the variable resistor 1a, a voltage approximately equal to the power source voltage Vcc is obtained across the variable resistor 1a. As a result, the voltage across the variable resistor 1a exceeds the threshold voltage V _TH of the inverter 132.
Output voltage is high level "H" to low level "L"
Switch to.

After that, the voltage across the variable resistor 1a gradually decreases according to the time constant CR. Here, R is the resistance value of the variable resistor 1a, and C is the capacitance value of the capacitor 2a. Due to this drop, the voltage across the variable resistor 1a drops below the threshold voltage V _TH of the inverter 132,
The output voltage of the inverter 132 switches from low level "L" to high level "H".

From the above, the reset signal S2 of low level "L" is obtained at the output terminal of the inverter 132 almost simultaneously with the connection of the normal package 10. In this case, the time width T of the reset signal S2 can be calculated based on the following equation. V _TH = Vcc {1-exp (T / CR)} Here, V _TH , Vcc, and C are fixed values. Therefore,
By adjusting R appropriately, the extinction timing of the reset signal S2 can be set after the end timing of the startup process.

That is, the reset signal S2 normally only instructs the start of the start-up processing at the timing of its generation, and the extinction timing does not always coincide with the end timing of the start-up processing. Therefore, the reset signal S
In order to prevent the connection notification signal S1 from being supplied until the start-up process is completed, the reset signal S
It is necessary to adjust the extinction timing of 2.

In the above description, the case where the disappearance timing of the reset signal S2 is adjusted by the variable resistor 1a has been described. However, the capacitor 2a may be a variable capacitor and the variable capacitor may be used for adjustment. However, in this case, the adjustment is generally more difficult than the case where the variable resistor is used.

The operation of the above structure will be described with reference to the timing chart of FIG. 7, t1 and t2 respectively indicate the connection timing of the normal package 10 and the disappearance timing of the reset signal S2, as in FIG.

When the normal package 10 is connected to the backboard 30, a high level "H" connection notification signal S1 as shown in FIG. 7 is generated on the connection notification line 11.
The connection notification signal S1 is supplied to the connection notification signal blocking unit 14.

On the other hand, when the normal package 10 is connected to the backboard 30, the normal package 10 is supplied from the external power source.
The power supply voltage Vcc is supplied to the on-board circuit. This allows
The reset signal generator 13 outputs the reset signal S2 at the low level "L" as shown in FIG. The reset signal S2 is supplied to the data sending unit 12 and the connection notification signal blocking unit 12. As a result, the data transmission unit 12 blocks the transmission of the data D1. The connection notification signal blocking unit 14 blocks the transmission of the connection notification signal S1.

After that, when the startup process of the normal package 10 is completed, the reset signal S2 disappears. As a result, the connection notification signal S1 blocked by the connection notification signal blocking unit 14 is supplied to the connection control unit 21. In FIG. 7, this connection notification signal S1 is shown as S4. As a result, the connection control unit 21 sends the access signal S to the data sending unit 12.
3 is supplied.

When the reset signal S2 disappears, the prohibition state of the data transmission operation of the data transmission section 12 is released. As a result, in synchronization with the access signal S3 supplied from the connection controller 21, the data transmitter 12 sends the data D
1 (D2) is transmitted. As a result, the connection control unit 21
Does not malfunction due to no response to access.

According to this embodiment described in detail above, the following effects can be obtained.

(1) Since the connection of the normal package 10 is notified to the connection control unit 21 after the startup processing of the normal package 10 is completed, the normal package 10 is accessed by the normal package 10. It will be started after it becomes possible to return a response to. This can prevent the connection control unit 21 from malfunctioning due to no response to the access.

(2) Further, when the normal package 10 is connected, the connection notification signal S1 is generated, and the supply of the connection notification signal S1 to the connection control unit 21 is blocked until the start-up process is completed. Since the connection notification after completion of the processing is realized, the object can be easily achieved only by adding the connection notification signal blocking unit 14 including the AND circuit 141 and the like to the conventional device.

(3) Furthermore, since the supply of the connection notification signal S1 is blocked by using the reset signal S2 for start-up processing, it is necessary to separately generate a signal dedicated to blocking the connection notification signal S1. You get the advantage of not having it.

Although one embodiment of the present invention has been described in detail above, the present invention is not limited to such an embodiment.

(1) For example, in the above embodiment, the connection notification signal S1 is generated by using the reset signal S2 for startup processing.
The case of blocking the supply of is explained. However, in the present invention, a signal dedicated to blocking the connection notification signal S1 may be generated and blocking may be performed using this signal. As a method of generating such a signal, for example, a method of using a rising signal of an element having a slow rising characteristic such as Xilinx can be considered. Further, it may be generated by using a programmable logic IC by ROM loading.

(2) In the above embodiment, the connection notification signal S1 is generated when the normal package 10 is connected, and the supply of the connection notification signal S1 is blocked until the startup process is completed. The case where the connection notification after the start-up process is realized has been described. However, in the present invention, the connection notification signal S1 may be generated only when the start-up process is completed. This is, for example, the reset signal S2
By accessing the flip-flop circuit.

(3) Furthermore, in the above embodiment, the case where the present invention is applied to the connection notification of the normal package 10 to the connection control unit 21 has been described. However, this invention
For example, it can be applied to a notification of connection of a peripheral device to a computer. In other words, this invention
The present invention can be generally applied to notification of connection between circuit units connected via a connector.

(4) In addition to this, it is needless to say that the present invention can be variously modified without departing from the scope of the invention.

[0066]

As described above in detail, according to the first invention, data is transmitted after outputting a signal instructing that the first circuit portion is connected to the second circuit portion. According to the second aspect of the invention, the data can be transmitted after outputting the signal instructing that the peripheral device is connected to the computer.

This makes it possible to prevent the connection control unit from malfunctioning due to the absence of a response to the access when connecting the normal package, for example.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration of an embodiment.

FIG. 2 is a block diagram for explaining the configuration of a conventional connection notification device.

FIG. 3 is a timing chart for explaining the operation of FIG.

FIG. 4 is a timing chart for explaining the operation of FIG.

FIG. 5 is a diagram showing an example of a specific configuration of a connection notification signal blocking unit.

FIG. 6 is a diagram showing an example of a specific configuration of a reset signal generator.

FIG. 7 is a timing chart for explaining the operation of FIG.

[Explanation of symbols]

10 ... Normal package, 11 ... Connection notification line, 12 ...
Data sending unit, 13 ... Reset signal generating unit, 14 ... Connection notification signal blocking unit, 20 ... Control package, 21 ... Connection control unit, 30 ... Backboard, 41, 42, 51, 52 ...
connector.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04L 29/10 H04L 29/08

Claims (8)

(57) [Claims] 1. When data is transmitted between a first circuit unit and a second circuit unit connected to the first circuit unit, a connection state between the first circuit unit and the second circuit unit is instructed. In a data transmission method for outputting a signal and transmitting data, the first circuit unit is not connected to the second circuit unit until the first circuit unit is ready to transmit data. Is output, and when the first circuit unit is ready to transmit data, the data transmission between the second circuit unit and the first circuit unit can be started. A data transmission method of transmitting data after outputting a signal instructing that the first circuit portion is connected to the second circuit portion. 2. The voltage level of the connection instructing signal is a signal instructing that the first circuit section is not connected while the start-up process of the first circuit section is being executed. Is a first voltage level, and the voltage level is used as a signal indicating that the first circuit section is connected after the start-up process of the first circuit section is completed. The data transmission method according to claim 1, wherein the control is performed so that the second voltage level is different from the level. 3. A data transmission method for outputting data by outputting a signal instructing a connection state between the peripheral device and the computer when the data is transmitted between the peripheral device and a computer connected to the peripheral device. , Outputting a signal indicating that the peripheral device is not connected to the computer until the peripheral device is ready to transmit data, and when the peripheral device is ready to transmit data, the transmission of the computer Data transmission method, in which data is transmitted after outputting a signal instructing that the peripheral device is connected to the computer in order to enable the start. 4. The signal instructing the connection is a signal instructing that the peripheral device is not connected while the startup processing of the peripheral device is being executed, and the voltage level thereof is the first voltage. The level is set to a second voltage level different from the first voltage level as a signal indicating that the peripheral device is connected after the startup process of the peripheral device is completed. 4. The data transmission method according to claim 3, wherein the data transmission is controlled as follows. 5. The second circuit section is provided while the first circuit section is receiving a signal indicating that the first circuit section is not connected to the second circuit section. Of data to the second circuit section is prohibited, and after transmitting a signal instructing that the first circuit section is connected to the second circuit section, transmission of data to the second circuit section is permitted. The data transmission method according to claim 1 or 2, wherein 6. The first circuit unit controls data transmission by an access signal from the second circuit unit, and the second circuit unit includes the first circuit in the second circuit unit. The access signal indicates prohibition of data transmission while receiving a signal indicating that the unit is not connected,
By outputting a signal instructing that the first circuit unit is connected to the second circuit unit, and then the access signal instructing permission of data transmission, the first circuit unit 6. The data transmission method according to claim 5, wherein transmission of the data is controlled. 7. The peripheral device is prohibited from transmitting data to the computer while the peripheral device is receiving a signal indicating that the peripheral device is not connected to the computer, and the peripheral device is controlled by the computer. 5. The data transmission method according to claim 3, wherein transmission of data to the computer is permitted after outputting a signal indicating that the device is connected. 8. The peripheral device is controlled to transmit data by an access signal from the computer, and the computer receives a signal indicating that the peripheral device is not connected to the computer. By outputting a signal indicating that the access signal prohibits data transmission and indicating that the peripheral device is connected to the computer, and then the access signal instructs permission of data transmission, 8. The data transmission method according to claim 7, wherein transmission of data in the peripheral device is controlled.