Electrical computers and digital data processing systems: input/ – Intrasystem connection – Bus access regulation
Reexamination Certificate
1999-10-14
2003-01-07
Dharia, Rupal (Department: 2181)
Electrical computers and digital data processing systems: input/
Intrasystem connection
Bus access regulation
C710S104000, C710S022000, C710S023000, C710S024000, C710S033000, C370S409000, C370S432000, C370S440000, C370S449000, C370S462000
Reexamination Certificate
active
06505264
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an information transmitting apparatus, an information receiving apparatus and an information transmitting/receiving apparatus, which are included in an information transmitting system, in which a serial bus is used to connect a plurality of apparatuses and information are transmitted between the apparatuses.
2. Description of the Related Art
Recently, a so-called IEEE 1394 standard (whose nominal name is “IEEE (Institute of Electrical and Electrical Engineers) Std.1394-1995 IEEE Standard for a High Performance Serial Bus”) is published as a new standard to transmit information in real time through a serial bus between a plurality of information apparatuses (for example, a personal computer, a digital video camera, an MD (Mini Disk) and the like). A digital video cameral, a personal computer and the like having a serial port based on this standard are manufactured.
This IEEE 1394 standard is standardized such that a plurality of information apparatuses (hereafter, merely referred as “nodes”) are connected through a serial bus to each other, and the information corresponding to a plurality of channels are transmitted in time sharing between these respective nodes (in this standard, it is standardized that the information can be transmitted by using a maximum of 63 different channels within a system connected through the serial bus).
In the IEEE 1394 standard, the initialization of a serial bus referred to as a so-called bus reset is standardized if another information apparatus is newly connected to a group of information apparatuses which are already connected through the serial bus to each other (namely, at a time of bus connection), or if one information apparatus is removed from the group of information apparatuses (namely, at a time of bus disconnection). Then, the following processes are carried out in conjunction with the bus reset, and a new connection manner is established (hereafter, this connection manner is referred to as a “topology”).
(1) In conjunction with an occurrence of the bus reset, a node which has detected the occurrence of the bus reset (namely, a node to which an information apparatus is newly connected or a node from which a previous connection is separated) sends a bus reset signal indicative of the occurrence of the bus reset to all nodes connected to the serial bus.
(2) After the bus reset, a tree identification is carried out to connect each node onto a tree. Then, a node located at a vertex of the connected tree is recognized as a route node.
(3) Then, the recognized route node instructs each node to recognize an identification number (ID number) peculiar to each node to identify each node within a tree system.
(4) An IRM (Isochronous Resource Manager) node is set, which serves as a node for managing the communication statuses (actually, use channels of the respective nodes and later-described transmission occupation periods) of all the nodes within the generated tree and which is displayed by other nodes at an identifiable manner.
(5) Finally, a bus manager node is set, which serves as a node for controlling the information transmission statuses of all the nodes is established.
A new topology after the bus reset is established by the processes at the above-mentioned five stages.
If the information is actually transmitted after the establishment of the topology, a transmitting node serving as a node to start the transmission of the information inquires of the IRM node the current communication statuses at the other nodes. If a transmission occupation period and a channel which the transmitting node desires to use are available, the transmitting node obtains a right of transmitting the information and starts the transmission of the information.
Next, the transmission occupation period will be schematically described below.
In the IEE 1394 standard, the information from each node is collectively transmitted for each information unit referred to as an isochronous cycle. This isochronous cycle includes an isochronous transmission area which contains information to be transmitted synchronously with the information contained in the other isochronous cycles, and an asynchronous transmission area which contains information to be transmitted asynchronously with and independently of the other information. The information within the isochronous transmission area is time-shared for each channel, so that different information is transmitted for each channel.
At this time, in the isochronous transmission area, it is standardized that a length of the isochronous transmission area within one isochronous cycle has a maximum of 100 &mgr;sec. Thus, it is necessary that a total of periods occupied by the information assigned to the respective channels within one isochronous transmission area for the transmission is equal to or less than 100 &mgr;sec. At this time, the transmission time occupied by one channel within the isochronous cycle is the above-mentioned transmission occupation period. In addition, this transmission occupation period may be referred to as a use band of a serial bus, or may be referred to as a use capacity of a serial bus depending on a case. Also, when a length of the isochronous transmission area is less than 100 &mgr;sec (including a case of zero) within one isochronous cycle, an area within the isochronous cycle other than the isochronous transmission area is exclusively used as the asynchronous transmission area.
By the way, it is standardized that in the serial buses connected to each other, if the bus reset is induced by the disconnection or connection of the bus during the transmission of the information, the transmission occupation period and the channel can be successively each node by the after the bus reset, which have been used before the bus reset.
In this case, for example, as shown in
FIG. 14A
, while information is transmitted from a node
100
through a serial bus
103
to a node
101
by using a channel
1
, if a node
102
is newly connected through a serial bus
104
to the node
101
, although a new topology is established after the bus reset, the information transmission can be continued between the node
100
and the node
101
and between the node
101
and the node
102
without any problem, as the node
102
uses a different channel
2
to transmit the information to the node
101
for example.
However, for example, as shown in
FIG.14B
, while information is transmitted from a node
105
through a serial bus
109
to a node
106
by using the channel
1
and also while information is transmitted from a node
108
through a serial bus
110
to a node
107
by using the channel
1
, if the node
106
and the node
108
are connected to each other through a serial bus
111
to thereby induce a bus reset, it is recognized on the standard that the transmission of the information is continued by using the same channel
1
as that before the bus reset, as for the node
105
, as mentioned above. At the same time, it is also recognized on the standard that the transmission of the information is continued by using the same channel
1
as that before the bus reset, as for the node
108
.
When this situation is considered from the standpoint of the node
107
, the node
107
can receive both the information transmitted by the node
105
and the information transmitted by the node
108
on the topology. However, in this case, both are transmitted by using the same channel
1
. Thus, the mixture of both the information is transmitted to the node
107
.
Here, in the IEEE 1394 standard, the node of receiving information (the node
107
, in the case of
FIG. 14B
) is allowed to only select a reception channel. Thus, in the case shown in
FIG. 14B
, the node
107
cannot judge whether it receives the information from the node
105
or receives the information from the node
108
. This results in a problem that the node
107
cannot normally receive the information.
On the other hand, when a transmission occupation period of the information transmitt
Hasebe Seiichi
Matsumaru Makoto
Minoshima Kunihiro
Murakoshi Sho
Ono Kinya
Dharia Rupal
Nixon & Vanderhye P.C.
Pioneer Corporation
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