JPH0851447A - Communication system - Google Patents

Abstract

PURPOSE:To select an input equipment to be a data source without using the logic name of each equipment by displaying a data output state to a communication control bus on an equipment having a function for outputting data to the bus. CONSTITUTION:Each equipment having a function of outputting data to a communication control bus is provided with an input selection key 1, an output state displaying LED2, a microcontroller 3, a synchronizing communication data processing block 4, and a communication layer processing block 5 and displays a data output state. The LED2 is turned off when no data are outputted, turned on when data are outputted, and when the equipment is selected as an input equipment from another equipment, is flickered. When the equipment is selected as an input equipment from the other equipment, the LED2 is turned on after being flickered when data output is possible, and turned off after being flickered when data output is impossible. When the equipment is selected as an input equipment during the output of data, the LED2 is turned on again after being flickered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention connects a plurality of electronic devices (hereinafter referred to as "devices") with a communication control bus capable of mixing control signals and data, and enables data communication between these devices. The present invention relates to a system for performing, in particular, a communication system characterized by a method of selecting an input device as a data source when each device inputs data from another desired device in the system.

[0002]

2. Description of the Related Art Conventionally, a video tape recorder (hereinafter referred to as "V
"TR". ), A television receiver (hereinafter referred to as “TV”), a camera-integrated VTR (hereinafter referred to as “CAM”), a computer, and other devices are connected by a communication control bus capable of mixing control signals and data. As a communication system for transmitting and receiving control signals and data between the above devices, a communication system using a P1394 serial bus is considered.

First, an example of such a communication system will be described with reference to FIG. This communication system includes devices A, B, C, D and E. These devices are VTRs, CAMs, computers, etc., as described above. Then, between the device A and the device B, between the device A and the device C, between the device C and the device D, and between the device C and the device E,
It is connected with a P1394 serial bus cable.
Since each device has a function of relaying control signals and data input from the cable of the P1394 serial bus, this system has a common P1 as shown in FIG.
It is equivalent to a communication system connected to a 394 serial bus.

Signal transmission in devices sharing a bus is performed in a predetermined communication cycle (for example, as shown in FIG. 10).
It is performed by time division multiplexing every 125 μs. Then, synchronization (Isochronou) for continuously transmitting data such as a digital AV signal at a constant data rate.
s) Communication and asynchronous transmission of control signals such as connection control commands at random (Asyncrono)
us) Both communication can be performed.

There is a cycle start packet CSP at the beginning of the communication cycle, and a period for transmitting the synchronous communication packet is set following the cycle start packet CSP. It is possible to perform a plurality of synchronous communications by assigning channel numbers 1, 2, 3, ... N to the respective synchronous communication packets. Then, after the transmission of the synchronous communication packets of all the channels to be transmitted is completed, the next cycle start packet CS
The period up to P is used for asynchronous communication.

[0006]

In the communication system configured as described above, consider a case where each device selects an input device, that is, a partner device as a source for inputting data to itself.

In a system in which a plurality of analog AV devices are connected with an analog AV cable and analog AV signals are transmitted and received between them, the number of the input terminal (line 1, 2, ...
It is possible to distinguish the input device from ().

However, in the communication system using the P1394 serial bus, each device receives the data transmitted from the other device through the same input terminal, and therefore the input device cannot be distinguished from the input terminal number. Therefore, the user may previously give each device a logical name (VTR1, VTR2, T
(V1 etc.) is set, and at the same time, it is considered to display the logical name set when selecting the input device in each device.

However, in order to do this,
Each device needs the function of setting and displaying the logical name. In addition, since the user needs to accurately store the set logical name, when the number of devices making up the communication system increases, there is a possibility that a selection error may occur due to a memory error.

The present invention has been made in order to solve such a problem, and an object thereof is to provide a communication system capable of selecting an input device without using a logical name of each device. To do.

[0011]

In order to solve the above problems, the present invention relates to a system in which a plurality of devices are connected by a communication control bus and communication is performed between these devices. It is characterized in that a device having a function of outputting is provided with means for displaying an output state of data to the communication control bus.

Here, the means for displaying the output state of data is a light emitting element such as an LED. Then, when selected as an input device, different display is performed depending on whether data can be output or not. Further, when the input device is further selected during data output, the display state is temporarily changed.

[0013]

According to the present invention, the output state of data is displayed in the device having the function of outputting data to the communication control bus. The output status of data is displayed, for example, by an LED
With the light emitting element such as, the light is turned off when the data is not output, the light is turned on when the data is output, and the light is turned on when the data is selected as an input device by another device.
Further, when selected as an input device from another device, if data output is possible, it blinks and then lights up, and if data output is not possible, it blinks and then goes out. When it is further selected as an input device during data output, it flashes and then lights up again.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a device to which the present invention is applied. Each device has an input selection key 1, an output status display LED 2, a microcontroller 3,
A synchronous communication data processing block 4 and a communication layer processing block 5 are provided.

The input selection key 1 is a key operated by the user when selecting an input device. The output status display LED 2 is an element that displays the output status of the synchronous communication data in the device.

The microcontroller 3 reads the state of the input selection key 1 and creates a command for making a request to output synchronous communication data or a request to stop the output of synchronous communication data to another device. When receiving an output request or an output stop request for synchronous communication data from another device, it sends a request to acquire a communication channel or a request to abandon the communication channel to the communication layer processing block 5. Further, the display state of the output state display LED 2 is controlled according to the output state of the synchronous communication data.

The synchronous communication data processing block 4 is a digital AV signal recording / playback processing unit or a tuner unit if the device is a VTR, and a monitor unit or a tuner unit if the device is a TV.

The communication layer processing block 5 sets the format of the synchronous communication packet and the asynchronous communication packet to P13.
The processing for converting between the format on the 94 serial bus and the format for the synchronous communication data processing block 4 and the microcontroller 3 and the processing for the physical layer and the link layer such as acquisition and abandonment of the right to use the bus.

FIG. 2 shows an example of an AV communication system to which the present invention is applied. This AV communication system has 5 VTRs
(VTR-A, VTR-B, VTR-C, VTR-D,
VTR-E). In this communication system, each VTR can independently flow two channels (channel 1 and channel 2) of synchronous communication data on the bus.

FIG. 3 shows the relationship between the display state of the output state display LED 2 and the output state of the synchronous communication data in the VTR to which the present invention is applied. It is off when synchronous communication data is not being output. Also, it is lit while outputting.
Further, it blinks when it is selected as an input device from another device.

The case where the VTR-D inputs the digital AV signal output from the VTR-C will be specifically described below with reference to FIG. In addition, in this figure,
The input selection key shown by a solid line indicates that it is currently pressed.

First, the VTR-D input selection key is pressed once. Then, the output state display LED of the VTR-A is turned on as shown in FIG. At this time, a digital AV signal is output from VTR-A, and VTR-D is receiving this. [Fig. 4 (a)]

Next, the VTR-D input selection key is pressed again. Then, the VTR-A stops the output of the digital AV signal, and the output status display LED thereof is turned off. And
A digital AV signal is output from the VTR-B, and the output status display LED thereof lights up. [Fig. 4 (b)]

Further, the VTR-D input selection key is pressed again. This time, similarly, VTR-C is selected and VTR-
D can receive the digital AV signal output from VTR-C. [Fig. 4 (c)]

If the VTR-B is already outputting a digital AV signal and the VTR-E is receiving it, and if the VTR-D selects the VTR-B,
Since the output display status LED of the VTR-B is already lit, 5 to notify the user that re-selection has been made.
Flashes for a second and then turns on again. [Fig. 4 (d)]

If each VTR cannot simultaneously input and output a digital AV signal, VTR-C is V
When receiving a digital AV signal from TR-B,
When -D selects VTR-C, the output status display LED of VTR-C blinks for 5 seconds and then turns off again. [Fig. 4
(E)]

Next, the processing of the microcontroller for realizing the operation of FIG. 4 will be described with reference to FIGS. In the device for input selection, the input selection key is monitored in S1 of FIG. 5, and if pressed, the process proceeds to S2. In S2, the device X, which is the output request destination device, is set. In this embodiment, the device X is first set to VTR-A. Then, the next time this processing is performed, it is set to VTR-B.
C, VTR-E are set, and VTR-A is set again.

In order to send an output request to the VTRs-A, B, C and E, it is necessary to identify each VTR on the bus, which is the node ID on the P1394 serial bus. Can be used. This node ID is
It is a physical address automatically given to each device by the method specified in IEEE-P1394 when each device is connected by a P1394 serial bus to form a communication system.

After setting the output request destination device in S2, S3
Then, it is checked whether or not there is a channel receiving the digital AV signal. If not received, an output request is transmitted to the device X in S6. If yes, S
In step 4, the output stop request is transmitted to the device outputting to that channel. Then, after receiving the processing end from the request destination device in S5, the process proceeds to S6.

Now, with reference to FIG. 6, the processing of the device that receives the output stop request in S5 will be described. First, if the output stop request command is received in S11, the process proceeds to S12. Then, in S12, it is confirmed whether or not the output request is received from the device other than the device that transmitted the output stop request and the output is performed.
(Each device, when receiving the output request, stores the requesting device until the output stop request is received, so it is possible to know whether or not the device is receiving the output request.) If not, The output is stopped in S13, and the output status display L
After turning off the ED, the processing end is transmitted to the device which has transmitted the output stop request command in S15. In the case of YES in S12, the output state display LED blinks for 5 seconds in S14,
Then it lights up. Then, the process proceeds to S15.

Next, with reference to FIG. 7, the processing of the device which receives the output request in S6 will be described. First, if the output request is received in S21, the process proceeds to S22. In S22, it is checked whether the digital AV signal is already being output.

If it is not outputting, it is checked in S23 whether it can be output. For example, check whether or not the user is inputting or both channels of the bus are in use and cannot be output. If the result can be output, S
At 24, the output state display LED is turned on and output is started.
Then, in S27, the VTR-D is notified of the output channel number. If the output is not possible in S23, the output state display LED blinks for 5 seconds in S25, and then is turned off. Then, in S28, the VTR-D is notified that the output is impossible.

If the output is in progress in S22, the output status display LED blinks for 5 seconds in S26 and then lights up. Then, the process proceeds to S27.

Referring again to FIG. VTR-D is S
In step 7, the device X that has made the output request waits for a response. Then, when a response comes, the process proceeds to S8. In S8, it is determined from the contents of the response whether or not the device X has succeeded in outputting the digital AV signal, and if successful, that is, if the device X has notified the channel number, the channel is received in S9. If the device X cannot output the digital AV signal in S8, the process proceeds to S1 without inputting.

The output state can be displayed not only by the LED but also by a lamp, an LCD or the like. In the case of a display device capable of displaying characters, it is also possible to display characters such as "outputting" and "selected". Further, in the above embodiment, an AV equipped with 5 VTRs is used.
Although it is a communication system, the present invention is also applicable to an AV communication system including a TV, a CAM, etc., a computer data communication system, and the like.

[0036]

As described in detail above, according to the present invention, in the device having the function of outputting data to the communication control bus, the output state of data (not outputting, during outputting, selected) is selected. Is displayed. Therefore, the function of setting the logical name of each device and displaying them is not necessary, which facilitates the device design and reduces the cost. Further, when the input device selection operation is performed, it is displayed that the selected device itself has been selected, so that there is no risk of erroneously selecting the input device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a device to which the present invention is applied.

FIG. 2 is a diagram showing an example of an AV communication system to which the present invention is applied.

FIG. 3 is a diagram showing a relationship between a display state of an output state display LED 2 and an output state of synchronous communication data in a VTR to which the present invention is applied.

FIG. 4 is a diagram showing a specific example of input selection.

FIG. 5 is a flowchart showing processing of a device that performs input selection.

FIG. 6 is a flowchart showing processing of a device that has received an output stop request.

FIG. 7 is a flowchart showing a process of a device that receives an output request.

FIG. 8 is a diagram showing an example of a communication system using a P1394 serial bus.

9 is a diagram equivalently describing the communication system of FIG.

FIG. 10 is a diagram showing an example of a communication cycle in a communication system using a P1394 serial bus.

[Explanation of symbols]

 1 ... Input selection key, 2 ... Output status display LED

Claims (4)

[Claims] 1. A system in which a plurality of electronic devices are connected by a communication control bus and data is communicated between the electronic devices, wherein the electronic device having a function of outputting data to the communication control bus is connected to the communication device. A communication system comprising means for displaying an output state of data to a control bus. 2. The communication system according to claim 1, wherein the means for displaying a data output state is a light emitting element. 3. The communication system according to claim 1, wherein when selected as an input device, different display is performed depending on whether data can be output or not. 4. The communication system according to claim 1, 2 or 3, wherein the display state is temporarily changed when further selected as an input device during data output.