JP3977240B2 - Electronics - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic device.
[0002]
[Prior art]
The IEEE 1394 standard is a serial bus standard for digital data communication. The IEEE 1394 standard was approved as the “IEEE 1394-1995 standard” in 1995, and the “P1394a standard” and the “P1394b standard” for clarifying this are also being studied. The serial bus according to the IEEE 1394 standard is referred to as “IEEE 1394 serial bus”.
[0003]
FIG. 1 represents a system according to the IEEE 1394 standard. The node 11 is an electronic device compliant with the IEEE 1394 standard, and the serial bus 12 (IEEE serial bus) is a cable compliant with the IEEE 1394 standard. That is, the electronic devices are connected via a cable. The connection terminal of the cable is a connector such as “4 pins” or “6 pins”.
[0004]
FIG. 2 shows a protocol according to the IEEE 1394 standard. The protocol according to the IEEE 1394 standard includes a physical layer 21, a link layer 22, a transaction layer 23, and a serial bus management 25 that manages the three layers. The physical layer 21 and the link layer 22 are hardware, and the transaction layer 23 and the serial bus management 25 are firmware. Note that an application layer 24 exists as an upper layer of the three layers.
[0005]
The physical layer 21 is involved in processing related to bus configuration at the time of bus reset such as “bus initialization”, “tree recognition”, and “self recognition”, processing related to bus acquisition at the time of packet transfer such as “arbitration”, and the like. . The link layer 22 is involved in processing related to packet transfer such as “isochronous transfer”, “asynchronous transfer”, and “asynchronous stream”. The transaction layer 23 is involved in processing related to instructions such as “Read”, “Write”, and “Lock”.
[0006]
The application layer 24 is not standardized in the IEEE 1394-1995 standard. Therefore, the application layer 24 is standardized as, for example, “SBP2 standard” or “SBP3 standard”. In the SBP2 standard, processing related to an initiator (a node that issues a command) and a target (a node that receives a command) is standardized.
[0007]
The serial bus management 25 includes a bus manager, an isochronous resource manager, and a node controller. The bus manager performs bus management such as “providing a topology map” and “providing a speed map”. The isochronous resource manager performs isochronous resource management such as “assignment of isochronous bandwidth” and “assignment of channel number”. The node controller performs node control.
[0008]
Finally, the advantages of the IEEE 1394 standard are listed. The first advantage is “guarantee of real-time property” by isochronous transfer. A second advantage is “Hot_Plug_In” that can be inserted and removed while the power is on. A third advantage is “Plug _ & _ Play” in which bus configuration is automatically executed in response to insertion / removal.
[0009]
[Problems to be solved by the invention]
Here, an electronic device that conforms to the IEEE 1394 standard, and that provides services to other electronic devices conforming to the IEEE 1394 standard connected via the IEEE 1394 serial bus will be considered.
[0010]
When the power of an electronic device connected to the bus is turned off, service provision from the electronic device to other electronic devices is stopped. However, since the electronic device whose power is turned off cannot transmit the bus reset signal, the bus reset is not executed and the bus configuration is not executed. Therefore, there is a problem that other electronic devices connected to the bus cannot immediately know that service provision from the electronic device whose power is turned off is stopped.
[0011]
As an invention for solving this problem, Japanese Patent Laid-Open No. 2001-160806 describes an invention for transmitting a bus reset signal before turning off the power. According to the description in this document, if a bus reset signal is transmitted before the power is turned off, a bus reset is executed by this and a bus configuration is executed. It is possible to know for certain that it has been stopped.
[0012]
Here, the means for other electronic devices to know the existence of services provided by a certain electronic device is “configuration ROM” that is executed following “bus reset”, “bus initialization”, “tree recognition”, and “self-recognition”. Read out ”. Each electronic device writes “service information” in its own configuration ROM, and other electronic devices read the “service information” from the configuration ROM to know the existence of the service. is there.
[0013]
Therefore, as described in Japanese Patent Laid-Open No. 2001-160806, by transmitting a bus reset signal before turning off the power so that other electronic devices can know that the service provision has been stopped, At the time of “reading the configuration ROM”, it is necessary to prevent other electronic devices from reading “information relating to the service” from the configuration ROM.
[0014]
However, according to the description in the document, the CPU processes the power-off request, the CPU issues a bus reset signal transmission request to the link layer controller, and the link layer controller sends the bus reset signal transmission request to the physical layer controller. Then, after confirming the completion of the operation, a request to turn off the power is permitted.
[0015]
Therefore, if it takes time from the transmission of the bus reset signal until the power is turned off, the other electronic device can read “information related to the service” from the configuration ROM in the meantime. Misunderstanding that service provision is continuing.
[0016]
Incidentally, in an electronic device compliant with the OpenHCI standard, which is an implementation standard of the IEEE 1394 standard, all reading from the configuration ROM is processed by the DMA context in the link layer controller, so as long as power is supplied to the link layer controller. Reading from the configuration ROM is possible. Since the completion of transmission of the bus reset signal cannot normally be executed without going through the link layer controller, only the power of the link layer controller cannot be turned off before that.
[0017]
Since the time from the transmission of the bus reset signal to the reading of the configuration ROM is about several milliseconds, it is practically necessary to prevent other electronic devices from reading the “information related to the service”. It can be said that there is enough from a simple point of view. However, the time until the power supply to the link layer controller is stopped depends on the design of each electronic device, and it can be said that there is no reliable means for speeding up the time until the power supply to the link layer controller is stopped.
[0018]
Even if other electronic devices can be prevented from reading “information related to the service”, another problem exists. This is a problem that a wasteful asynchronous read transaction occurs on the bus because other electronic devices try to read “information related to the service”. The occurrence of a read retry following a read failure causes a wasteful consumption of the bus bandwidth.
[0019]
Therefore, according to the present invention, when an electronic device that provides a service to another electronic device connected via a serial bus stops providing the service when the power is turned off, It is an object to make it possible for a device to know relatively quickly that the service is stopped.
[0020]
In particular, the present invention relates to an electronic device that conforms to the IEEE 1394 standard, and is turned off in an electronic device that provides services to other electronic devices conforming to the IEEE 1394 standard connected via the IEEE 1394 serial bus. Accordingly, it is an object of the present invention to make it possible for other electronic devices to know relatively quickly that the service is stopped when the service is stopped.
[0021]
[Means for Solving the Problems]
According to the first aspect of the present invention (electronic device), when an electronic device that provides a service to another electronic device connected via a serial bus stops providing the service, a bus reset is performed. In the self-recognition process after sending a signal and performing a bus reset, even if the link layer controller is actually active, sending a self-recognition packet with the bit indicating the existence of the link layer set to 0 Features.
[0024]
The invention (electronic device) described in claim 2 is an electronic device compliant with the IEEE 1394 standard, and provides a service to another electronic device compliant with the IEEE 1394 standard connected via the IEEE 1394 serial bus. When the electronic device stops providing the service, the self-recognition process after transmitting the bus reset signal and executing the bus reset, even if the link layer controller is actually active, A self-recognition packet in which a bit indicating presence is set to 0 is transmitted.
[0025]
The invention (electronic device) according to claim 3 relates to the invention (electronic device) according to claim 1 or 2, and is a bit indicating the presence of the link layer in the self-recognition packet by an operation of a register of the physical layer controller. Is set to 0.
[0026]
The invention (electronic device) described in claim 4 relates to the invention (electronic device) described in claim 1 or 2 , and indicates the presence of the link layer in the self-recognition packet by operating the LPS terminal of the physical layer controller. The bit is set to 0.
[0027]
The invention (electronic device) according to claim 5 relates to the invention (electronic device) according to any one of claims 1 to 4 , wherein the service is one of a print service, a facsimile service, and a scan service. Alternatively, two or more are provided.
[0029]
In the invention (electronic device) according to claim 1 or 2 , when stopping providing the service, a bus reset signal is transmitted and a self-identification packet in which a bit indicating the presence of the link layer is set to 0 is transmitted. By doing so, when the service provision is stopped as the power is turned off, the other electronic devices can know relatively quickly that the service provision is stopped.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described.
[0031]
FIG. 3 represents a system according to the IEEE 1394 standard. The node 11 is an electronic device compliant with the IEEE 1394 standard, and the serial bus 12 (IEEE serial bus) is a cable compliant with the IEEE 1394 standard.
[0032]
FIG. 4 shows an electronic device 41 which is an example of an embodiment of the present invention. 4 includes a physical layer controller 42, a link layer controller 43, a CPU 44, and a configuration ROM 45. The electronic device 41 in FIG. 4 is a node 11 configuring the system in FIG. 3 and provides a service to the other nodes 11 configuring the system in FIG. For example, there are a print service, a facsimile service, a scan service, and the like. One or more of these may be provided.
[0033]
FIG. 5 shows a hierarchy of information in the configuration ROM 45 of FIG. The electronic device 41 writes information related to the type of service (print service, facsimile service, scan service, etc.) that is “information related to the service” using the Instance_directory 51 and the accompanying Feature_directory 53 and Keyword_leaf 54 in FIG. Also, information related to the protocol for using the service, which is “information related to the service”, is written using the Unit_directory 52 and the Feature_leaf 53 and Dependent_leaf 55 associated therewith in FIG. Note that an electronic device compliant with the IEEE 1394 standard has a configuration ROM in a region of 1024 bytes from the offset FFFFF0000400h in the electronic device and a region that can be traced by link information from the region.
[0034]
FIG. 6 shows the format of Bus_information_block 56 of FIG. The electronic device 41 that has rewritten the information in its own configuration ROM 45 has rewritten the value of generation_field 61 in Bus_information_block 56, and the other electronic devices have rewritten the information in configuration ROM 45 by reading the value of this generation_field 61. Can know.
[0035]
Hereinafter, each embodiment will be described on the premise of the settings shown in FIGS.
[0036]
(First embodiment)
In the first embodiment, when the electronic device 41 in FIG. 4 stops providing the service due to the power being turned off or the like, first, information related to the service is deleted from the configuration ROM 45. What is deleted here is information on the type of service, information on a protocol for using the service, and link information written in a parent directory related to the information.
[0037]
After deleting the information related to the service, the electronic device 41 in FIG. 4 rewrites the value of the generation_field 61 and transmits a bus reset signal. That is, the CPU 44 issues a bus reset signal transmission request to the link layer controller 43, and the link layer controller 43 sends a bus reset signal transmission request to the physical layer controller 42. Thereby, a bus reset is executed. In the case where the provision of service is stopped when the power is turned off, the power is actually turned off after the bus reset signal is transmitted.
[0038]
Subsequent to the bus reset, another electronic device reads the value of generation_field 61 from the configuration ROM 45 of the electronic device 41 in FIG. At this time, since the value of generation_field 61 is rewritten, the other electronic device can know that the information in the configuration ROM 45 has been rewritten. As a result, the other electronic device discards the “service-related information” for the electronic device 41 in FIG. 4 and tries to read a new “service-related information”. However, since the information related to the service has been deleted and cannot be read as a matter of course, the other electronic device can know that the provision of the service has been stopped.
[0039]
In addition, when the first embodiment is applied to an electronic device compliant with the OpenHCI standard, other electronic devices can read from the configuration ROM “service-related” without increasing the time until the power supply to the link layer controller is stopped. There is an advantage that information cannot be read out.
[0040]
Further, the operation of deleting the information related to the service from the configuration ROM and transmitting the bus reset signal has an advantage that it can be realized by improving the firmware of the conventional electronic device compliant with the IEEE1394 standard. . This is advantageous in terms of cost as compared with the case of improving the link layer controller and the physical layer controller.
[0041]
(Second embodiment)
In the second embodiment, the electronic device 41 of FIG. 4 first transmits a bus reset signal when it stops providing the service due to the power being turned off. That is, the CPU 44 issues a bus reset signal transmission request to the link layer controller 43, and the link layer controller 43 sends a bus reset signal transmission request to the physical layer controller 42. Thereby, a bus reset is executed.
[0042]
Here, in the system according to the IEEE 1394 standard as shown in FIG. 3, the self-recognition process is executed after the bus reset is executed. In the self-recognition process, each electronic device transmits a self-recognition packet. FIG. 7 shows the format of the self-recognition packet. Each electronic device executes bus configuration based on the self-recognition packet.
[0043]
In the second embodiment, the electronic device 41 of FIG. 4 is a bit indicating the presence of the link layer in the self-recognition process after the bus reset even though the link layer controller 43 is actually active. A self-recognition packet having “L bit” set to 0 (when the link layer controller 43 is active, the L bit is normally 1) is transmitted. In the case where service provision is stopped as the power is turned off, the power is actually turned off after the self-recognition packet is transmitted.
[0044]
The self-recognition packet transmitted from the electronic device 41 in FIG. 4 is received by another electronic device. The other electronic device determines that the link layer controller 42 of the electronic device 41 in FIG. 4 is not active because the L bit of the self-recognition packet is set to 0. That is, with this, the other electronic device can know that the provision of the service is stopped.
[0045]
In the system according to the IEEE 1394 standard as shown in FIG. 3, the configuration ROM is read after the self-recognition process is executed. However, the configuration ROM 45 of the electronic device 41 in FIG. 4 is not read by another electronic device. This is because in order to read the configuration ROM of an electronic device, the link layer controller of the electronic device needs to be active. Therefore, there is an advantage that a useless transaction for reading the configuration ROM 45 of the electronic device 41 of FIG. 4 does not occur.
[0046]
Finally, an example of specific means for setting the L bit in the self-recognition packet to 0 will be described with respect to the electronic device 41 of FIG.
[0047]
As a first example, by operating the register of the physical layer controller 42 before transmission of the bus reset signal, the L bit in the self-recognition packet transmitted after transmission of the bus reset signal is set to 0. For example, when applied to an electronic device compliant with the P1394a standard, the LCt1 bit of the register located at address 4 (0100 ₂ ) may be set to 0.
[0048]
As a second example, by operating the LPS (LINK_Power_Status) terminal of the physical layer controller 42 before transmission of the bus reset signal, the L bit in the self-recognition packet transmitted after transmission of the bus reset signal is set to 0. To do. The LPS terminal is a terminal for notifying the physical layer controller 42 whether or not the link layer controller 43 is active, and is normally connected to a corresponding terminal (terminal to which an active signal is output) of the link layer controller 43. The For example, the signal input to the LPS terminal may be a logical AND between the active signal of the link layer controller 43 and a signal that becomes inactive due to a power OFF request (a logical NOT request for the power OFF request).
[0049]
Note that the operation of the registers and LPS terminals of the physical layer controller has an advantage that the physical layer controller of a conventional electronic device compliant with the IEEE 1394 standard can be realized as it is. This is advantageous in terms of cost compared with the case where the physical layer controller is improved.
[0050]
【The invention's effect】
In this way, the present invention provides an electronic device that provides a service to another electronic device connected via a serial bus when the service is stopped when the power is turned off. It is possible to make it possible to know relatively quickly that the electronic equipment of the service is stopped.
[0051]
In particular, the present invention is an electronic device that conforms to the IEEE 1394 standard, and is turned off in an electronic device that provides services to other electronic devices conforming to the IEEE 1394 standard connected via the IEEE 1394 serial bus. When the provision of the service is stopped, the other electronic device can know relatively quickly that the provision of the service is stopped.
[Brief description of the drawings]
FIG. 1 represents a system according to the IEEE 1394 standard.
FIG. 2 represents a protocol according to the IEEE 1394 standard.
FIG. 3 represents a system according to the IEEE 1394 standard.
FIG. 4 illustrates an electronic device that is an example of an embodiment of the present invention.
FIG. 5 shows a hierarchy of information in the configuration ROM.
FIG. 6 shows a format of Bus_information_block.
FIG. 7 shows a format of a self-recognition packet.
[Explanation of symbols]
11 Node 12 Serial bus 21 Physical layer 22 Link layer 23 Transaction layer 24 Application layer 25 Serial bus management 41 Electronic device 42 Physical layer controller 43 Link layer controller 44 CPU
45 Configuration ROM
51 Instance_directory
52 Unit_directory
53 Feature_directory
54 Keyword_leaf
55 Dependent_leaf
56 Bus_information_block
61 generation_field

Claims (5)

In electronic devices that provide services to other electronic devices connected via a serial bus,
A bit indicating the presence of the link layer in the self-aware process after sending a bus reset signal and performing a bus reset when actually stopping the service, even though the link layer controller is actually active An electronic apparatus characterized by transmitting a self-recognition packet in which is set to 0. An electronic device that conforms to the IEEE 1394 standard and provides services to other electronic devices that conform to the IEEE 1394 standard connected via the IEEE 1394 serial bus.
A bit indicating the presence of the link layer in the self-aware process after sending a bus reset signal and performing a bus reset when actually stopping the service, even though the link layer controller is actually active An electronic apparatus characterized by transmitting a self-recognition packet in which is set to 0. The operation of the physical layer controller registers, electronic device according to claim 1 or 2 bits indicating the presence of a link layer in said self-recognition packet, characterized in that set to 0. The operation of the physical layer controller of LPS terminal electronic device according to claim 1 or 2 bits indicating the presence of a link layer in said self-recognition packet, characterized in that set to 0. As the service, the print service, fax service, one or electronic device according to any one of claims 1 to 4, characterized in that it provides two or more of the scan service.

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