JP2003032269A - Method and device for managing serial bus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide serial bus managing method/device for reserving bus use, by considering data communication which is performed at present, in a bus realizing transmission by securing a transmission band and a transmission channel. SOLUTION: Imperfections, in the reservation managing method of timer recording by using time-schedule register in conventional TSM, are improved. When isochronous transmission, whose termination time is not clear, is overlapped with the reservation time of another isochronous transmission, it is determined whether both isochronous transmissions are possible. When one isochronous transmission becomes disabled, a warning is issued to a user. Thus, reservation management including future time can be made, while compatibility with conventional constitution is kept, as it is, without confusing the user.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial bus management method and a serial bus management device in a bus system in which two or more devices are connected.

[0002]

2. Description of the Related Art Recently, a mechanism for transmitting and receiving data between various devices has been developed. For example, as a bus standard for exchanging digital data, IEEE
A high-speed connection interface using a serial data transfer protocol called 1394 standard is becoming popular. I
The greatest feature of the EEE 1394 standard is that isochronous transmission is used for video signals, audio signals, and the like that require real-time characteristics.

In isochronous transmission, it is guaranteed that a certain amount of data is communicated at regular intervals, and that an unspecified number of nodes can receive data flowing on the same channel at the same time. have. For detailed specifications, refer to the IEEE 1394 Std 1394-1995 standard “IEEE Standard for a High Performance Seria”.
lBUS ”.

Here, a channel means a path for transmitting an isochronous signal between one transmitting device and one or more receiving devices, and the band is the size of a packet transmitted on one channel. It refers to the amount of bandwidth (time) of isochronous transmission that is proportional and inversely proportional to the transmission rate.

When performing isochronous transmission, an isochronous resource manager (Isochronous Resource Manager) is used.
ager: Hereinafter referred to as IRM. There is always a serial bus management mechanism called) on the bus. In order to perform isochronous transmission, the BANDWIDTH_AVAILABLE register, which is a register for bandwidth reservation provided by the IRM, and the CANNELS_AVAILABLE register, which is a register for channel reservation, are used to declare the isochronous resource reservation, and both registers are registered. Secure the transmission bandwidth and the transmission channel.

However, the above-mentioned serial bus management mechanism only secures the current transmission bandwidth and transmission channel, and does not have the concept of time reservation of bandwidth and channel. Therefore, when a certain bus is desired to be used at a specific time in the future, there is a problem that there is no guarantee that the bandwidth and channel required at that time can be reliably used.

Therefore, as a conventional technique for solving this problem, Japanese Patent Laid-Open No. 11-168473 discloses a technique relating to a serial bus management device. FIG. 10 is a block diagram showing the configuration of a node having a conventional serial bus management device. As shown in FIG. 10, the serial bus management device 110 includes a CPU 111, a system controller 112, a clock 113, and a memory 11.
4 and the serial bus controller 115. The CPU 111 is the serial bus management device 110.
Manage each part of. The system controller 112 is C
It has an interface function for the PU 111, the memory 114, the clock 113, and the serial bus controller 115. The serial bus controller 115 uses the IEEE13
It is for controlling the data transmission of the 94 serial bus 106, and is connected to the IEEE 1394 serial bus 106. With this configuration, a register called TIME_SCHEDULE register is provided to the IEEE 1394 serial bus. In the following description, the conventional serial bus management device 110 is referred to as a "Time Schedule Manager (TSM)".

FIG. 11 is a block diagram showing a configuration of a bus system including a node having a conventional serial bus management function (TSM). The bus system 101 is an AV
The HDD 102, the DVCR 103, the personal computer (hereinafter referred to as PC) 104, and the set top box (hereinafter referred to as STB) 105. Is. AV-HDD 102 and DVCR 103
, DVCR 103 and PC 104, AV-H
Between the DD 102 and the STB 105, IEEE is used.
It is connected by the 1394 bus 106. System 101
In, the physical layer transmission capability is assumed to be S100.
The TSM 110 configured as shown in FIG.
Is incorporated in the PC 104, for example.

In the bus system 101, as an example, AV
-The HDD 102 is the IRM, and the BANDWI described above is used.
The DTH_AVAILABLE register and the CHANNELS_AVAILABLE register are provided for the IEEE1394 serial bus. In addition, this node is
ster: Hereinafter referred to as CM. ), It also broadcasts a cycle start packet to the bus.

In isochronous transmission, a node having a CM function broadcasts a cycle start packet to the entire bus at a cycle of 125 μsec. 12
[Fig. 3] is a state diagram of IEEE 1394 isochronous transmission. As shown in FIG. 12, when the cycle start packet 121 is broadcast, the isochronous packet 122 can be transmitted.

A TIME_SCHEDULE register is provided in the CSR space of the PC 104 shown in FIG. TIME_SC
The HEDULE register is actually the memory 114 of FIG. 10, and the TIME_SCHED from the serial bus controller 115.
When there is a write or read request to the ULE register, the CPU 111 writes or reads to the memory 114, and the serial bus controller 11
The result is returned to 5.

As described above, according to the prior art disclosed in the above publication, BANDWIDTH_AVAILABL managed by IRM is used.
In addition to the E register and CHANNELS_AVAILABLE register,
By newly using the TIME_SCHEDULE register of TSM, the reservation information on the time axis is managed by the TIME_SCHEDULE register, and when the reservation time comes, the BANDWIDTH_AVAILABLE register and C
By using the HANNELS_AVAILABLE register to secure an isochronous band and an isochronous channel, reservation management including future time, which was impossible in the past, can be performed while maintaining compatibility with the conventional configuration.

[0013]

The above-mentioned prior art is effective if all reservations of the isochronous band and the isochronous channel are reserved. However, in practice, isochronous transmission often occurs without performing the reservation operation. For example, this corresponds to a case where timer recording of a broadcast program received by the STB 105 is reserved by the AV-HDD 102 while dubbing from the AV-HDD 102 to the DVCR 103 shown in FIG. At this time, since the end time of the dubbing operation is usually unknown, it cannot be described in the TIME_SCHEDULE register. Therefore, the user is the AV-HDD 102.
Although it is possible to make a timer recording reservation at, it is possible that dubbing will continue even at the reserved time. In that case, timer recording or dubbing may not be possible, which may confuse the user.

That is, the conventional serial bus management device has a problem in that the reservation is established if the band and the channel required at the time of executing the reservation remain. Further, there is a problem that it does not support isochronous transmission in which the start time or the end time is not fixed.

Therefore, the present invention was created in order to solve the above-mentioned problems, and is currently being executed in a bus capable of performing transmission with a secured transmission band and transmission channel, such as an IEEE 1394 serial bus. An object of the present invention is to provide a serial bus management method and a serial bus management device capable of making a bus usage reservation in consideration of data communication.

[0016]

The present invention has the following structure as means for solving the above problems.

(1) In a serial bus management method for managing data communication carried out between a plurality of devices via a serial bus, if the end time of the data communication currently carried out is unknown, the data currently carried out It is characterized in that the transmission bandwidth is calculated on the assumption that the communication is performed even after the predetermined time, and whether the data communication to be performed after the predetermined time is possible or not.

In this configuration, when the end time of the data communication currently being performed is unknown, the data communication currently being performed is performed even after the predetermined time in order to determine whether or not the data communication to be performed after the predetermined time. The transmission bandwidth is calculated to manage the data communication performed between a plurality of devices via the serial bus. Therefore, since it is determined whether or not the data communication to be performed after the predetermined time is taken into consideration in consideration of the data communication currently being performed, it becomes possible to support the isochronous transmission in which the start time or the end time is not set, and the user is confused. Each node can be used without. Further, reservation management including future time can be performed while maintaining compatibility with the conventional configuration.

(2) If there is a possibility that data communication cannot be performed after a predetermined time in the calculated transmission bandwidth after the predetermined time, the fact is notified.

In this configuration, if the data communication currently being performed is also performed after the predetermined time, there is a possibility that the data communication performed after the predetermined time may become impossible due to the transmission bandwidth. Notify that it may be possible. Therefore, the user can know in advance the state of the serial bus when data communication is performed after a predetermined time.

(3) When the notification is given, it is possible to select between continuing the data communication currently being performed and reserving the data communication performed after a predetermined time.

In this configuration, when it is informed that there is a possibility that it will be impossible due to the relation of the transmission bandwidth, the ongoing data communication is continued and the data communication is reserved after a predetermined time. Can be selected. Therefore, when there is a possibility that the data communication cannot be performed after the predetermined time, the user can select the data communication to be performed after the predetermined time, and the user can save the future time without being confused. It becomes possible to perform reservation management including.

(4) The serial bus is IEEE13
The bus is compliant with the 94 standard.

In this structure, data communication between a plurality of devices is carried out via a serial bus conforming to the IEEE 1394 standard. Therefore, it becomes possible to transmit a video signal, an audio signal, etc. in real time using isochronous transmission.

(5) In a serial bus management device that manages data communication performed between a plurality of devices via a serial bus, if the end time of the current data communication is unknown, the current data It is characterized by further comprising control means for calculating the transmission bandwidth assuming that the communication is performed even after the predetermined time, and determining whether or not the data communication to be performed after the predetermined time.

In this configuration, when the end time of the data communication currently being performed is unknown, the serial bus management device determines that the data communication currently being performed is still being performed after a predetermined time, and determines the transmission bandwidth. By using the control means for calculating and judging whether or not the data communication to be performed after a predetermined time,
Manages data communication between multiple devices via a serial bus. Therefore, it becomes possible to support isochronous transmission in which the start time or the end time is not determined, and the user can use each node without confusion. Further, reservation management including future time can be performed while maintaining compatibility with the conventional configuration.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION In the embodiments of the present invention, a case where the invention is applied to a bus system connected by an IEEE 1394 serial bus will be described as in the prior art disclosed in the above publication. Further, various settings and configurations will be described in the same manner as the above-mentioned publication so that the contents of the publication can be easily compared.

FIG. 1 is a block diagram showing a schematic configuration of a system bus including a node having a serial bus management device according to an embodiment of the present invention. Bus system 1 is A
This is a configuration including a V-HDD 2, a DVCR 3, a PC 4, and an STB 5. The STB 5 includes a control means and a notification means (not shown). D between AV-HDD2 and DVCR3
The VCR 3 and the PC 4 and the AV-HDD 2 and the STB 5 are connected by the IEEE 1394 bus 6, respectively. In the bus system 1, the physical layer transmission capability is S
It is assumed to be 100. Further, the serial bus management device according to the embodiment of the present invention is incorporated in, for example, the PC 4, and its configuration is the TSM 1 of FIG.
Same as 10.

A physical_ID is assigned to each node in accordance with the rules of IEEE1394. AV-HD
D2 is physical_ID = 3, DVCR3 is physical_ID =
1, PC4 physical_ID = 0, STB5 physical_ID
= 2.

In the bus system 1, as an example, physical
The AV-HDD 2 with _ID = 3 is the IRM, and the BANDWIDTH_AVALABLE register and CHANNELS_AVAILAB described above are used.
The LE register is provided for the IEEE 1394 serial bus.

BANDWIDTH_AVALABLE register and CHANNELS
The _AVAILABLE register has the following configuration. Figure 2
[Fig. 7] is a bit configuration diagram of a BANDWIDTH_AVAILABLE register in IEEE1394. FIG. 3 shows the IEEE139
6 is a bit configuration diagram of a CHANNELS_AVAILABLE register in FIG. These registers are mapped to an address space conforming to the CSR (Control and Status Register) architecture (ISO / IEC-13213) of the IEEE 1394 standard. The BANDWIDTH_AVAILABLE register has 32 bits (1 quadlet (Quadlelet) as shown in FIG.
t)) register, the upper 19 bits are reserved area (reser
ved), and the lower 13 bits (bw_remaining) represent the remaining amount of the band. Bandwidth unit is BAND WIDTH A
LLOCATION UNIT (hereinafter referred to as BWU), which is defined as the time it takes to transmit one quadlet at a speed of 1600 Mbps. 1BWU is about 20nsec (32bits
/ 1600Mbps = 20nsec). The initial value of bw_remaining is
4915d [BWU] (= 1001100110011b), which means the maximum amount of communication band of an isochronous signal that can be transmitted per cycle, and is a value corresponding to 100 μsec. In other words, a maximum of 8 out of 125 μsec per cycle
Up to 0% can be used for isochronous transmission. In the above notation, the binary notation is suffixed with a numeral b, and the decimal notation is suffixed with a numeral d.

To start the isochronous transmission, it is necessary to rewrite the value of this register. For example, 125
If you want to secure 10 μsec of μsec, 10 μsec
sec is equivalent to about 500d [BWU], so bw_remaining is 4915
Bandwidth is secured by rewriting as d-500d = 4415d [BWU] (= 1000100111111b).

The transmission channel is secured by the CA shown in FIG.
This is done using the NNELS_AVAILABLE register. This register describes the current channel usage status on the network. It consists of 64 bits (2 quadlets), and the upper 32 bits are CHANNELS_AVAILABLE_HI,
The lower 32 bits are defined as CHANNELS_AVAILABLE_LO. And on the LO side, channels 0 to 31, HI
On the side, the usage statuses of channels 32 to 63 are shown. A value of 1 means that the channel is available, and a value of 0 means that the channel is being used. The AV-HDD 2 also has a CM function and broadcasts a cycle start packet to the bus.

In the CSR space of PC4, TIME_SCHEDULE
Registers are provided. The TIME_SCHEDULE register has the following configuration. FIG. 4 is a bit configuration diagram of the TIME_SCHEDULE register. The bit structure shown in FIG. 4 is the same as the bit structure shown in the above publication. The TIME_SCHEDULE register has one
3 quadlet registers are defined corresponding to the schedule. In addition, in order to manage multiple time schedules, TIME from # 0 to #M (M is an integer of 0 or more)
The _SCHEDULE register is defined as consecutive addresses.

In the TIME_SCHEDULE register, the upper 7 bits (reserved) of the first quadlet are not used. The next 6 bits represent the physical_ID of the node that wrote the time schedule, and the next 6 bits represent the request_channel_number, which is the channel number to be reserved. The next 13 bits are the band to be secured re
Represents quest_bw. The second quadlet represents the time at which the reservation starts, in seconds. BU of IEEE 1394
The upper 25 bits are set to st according to the definition of the S_TIME register.
art_second_count_hi, lower 7 bits start_second_co
It is defined as unt_lo. The third quadlet represents the time when the reservation ends in seconds. IEEE139
According to the definition of the BUS_TIME register of 4, the upper 25 bits are end_second_count_hi and the lower 7 bits are end_second_
It is defined as count_lo.

The BUS_TIME register has the following structure. FIG. 5 is a bit configuration diagram of the BUS_TIME register in the IEEE 1394 serial bus. A 32-bit second counter can count time of about 136 years. Although 32 bits are defined by being divided into second_count_hi and second_count_lo, there is no particular meaning. The initial value of the TIME_SCHEDULE register is request_b
w = 0000000000000b. The other bits may have any value. By setting like this, what number TIME_SCHEDULE
You can determine how many hours the register has been reserved.

Next, the operation of the system including the node having the serial bus management device according to the embodiment of the present invention will be described with reference to a flowchart. FIG. 6 is a flowchart illustrating an operation of a system including a node having a serial bus management device according to an exemplary embodiment of the present invention. First, the operation when the STB 5 makes a timer recording reservation for the AV-HDD 2 will be described.

The STB 5 reads the time schedule register for making a reservation (s1), and confirms whether the necessary band and channel remain at the time of executing the reservation (s2). If the necessary band and channel do not remain, the reservation cannot be established, so the reservation is canceled (s6), and the process ends.

On the other hand, in s2, if the band and channel required at the time of executing the reservation remain, the reservation may be established. Therefore, the IRM is inquired about the current status of isochronous transmission (s
3). As a result, if the currently used bandwidth and channel continue to be used until the reserved time, if the currently used isochronous transmission and the scheduled isochronous transmission at the time of reservation execution (in the future) can be performed normally, TIME_SCHEDUL
The band and channel used at the reserved time are written in the E register (s4). When the IRM is inquired about the status of the isochronous transmission currently used in s3, if isochronous transmission is not currently performed, s4 is unconditionally executed. Then complete the reservation (s
5), the process ends.

On the other hand, in s3, if the currently used band and channel are continuously used until the reserved time,
If there is a problem such as running out of bandwidth or channels during reservation execution, isochronous transmission will overlap during reservation execution. Therefore, the control means (not shown) of the STB 5 warns (notifies) the user that the desired isochronous transmission is not performed, using the notifying means (not shown) (s7). The user who receives the warning (notification) determines whether or not to make a reservation (s8). In s8, if the currently used isochronous transmission is stopped by the reservation execution time and the reservation operation is prioritized, the band and channel used at the reservation time are written in the TIME_SCHEDULE register (s9), and the reservation is completed (s5 ), The processing ends. If the execution of the reservation is stopped in s8, the reservation is stopped (s6), and the process ends.

Next, referring to FIGS. 6 and 7, AV-HD
While D2 is dubbing to DVCR3, STB5 is AV
The operation of making a timer recording reservation in the HDD 2 will be described. FIG. 7 shows TIME_SCHEDUL for explaining the reservation operation.
It is a bit configuration diagram of an E register.

When the AV-HDD 2 is dubbing to the first DVCR 3, for example, if a band of 40 Mbps is transmitted on the channel 0, the transmission capacity of the AV-HDD 2 and the DVCR 3 is S100, so 40 Mbps is 2500d [. BW
U], and therefore BANDWIDTH_AVAILABLE in FIG.
Bw_remaining, which is the lower 13 bits of the register, is 4915d-
The bandwidth is secured by rewriting 2500d = 2415d [BWU] (= 0100101101111b). The transmission channel is secured by using channel 0, and the lower 32 bits of the CANNELS_AVAILABLE register shown in FIG.
s_available_lo to 11111111111111111111111111111110b
It is achieved by rewriting.

At this time, the STB 5 makes a timer recording reservation. First, the TIME_SCHEDULE register is read (s1), and it is confirmed whether or not the necessary band and channel remain at the time of executing the reservation ( s2). Since it is in the initial state as shown in FIG. 7A, it is confirmed that no reservation is currently made, and then s3 is executed.

Since the processing differs depending on the size of the band used for timer recording, description will be made separately for each case.

(1) When the bandwidth used for timer recording is small For example, timer recording from 6:00 to 18
Until the time, if the band of 25 Mbps is transmitted on channel 1, as shown in FIG. 7B, physical_ID = 000
000b, request_channel_number = 000001b, request_bw = 0
011000011011b, start_second_count_hi = 0000000000000
000010101000b, start_second_count_lo = 1100000b, end_
second_count_hi = 0000000000000000111111010b, start_
second_count_lo = 0100000b. This value is TIME_SCHE
Just write to the DULE register. For the sake of clarity, BUS_TIME is set to 0 o'clock on October 10th. Here, 25 Mbps corresponds to about 1563d [BWU]. Therefore, request_bw = 0011000011011b.

At this time, in s3, if it is assumed that the currently used band and channel are continuously used until the reservation is executed, the remaining bandwidth when the reservation is executed is 2415d-
Since 1563d = 852d [BWU], it can be seen that there is no problem even if the reservation is executed. Therefore, the TIME_SCHEDULE register is rewritten as shown in FIG. 7B (s4), the reservation is completed (s5), and the process ends.

(2) When the bandwidth used for timer recording is large For example, by timer recording, from 6 o'clock on October 10 to 18
Until the time, if the band of 40 Mbps is transmitted on channel 1, as shown in FIG. 7C, physical_ID = 000
000b, request_channel_number = 000001b, request_bw = 0
100111000100b, start_second_count_hi = 0000000000000
000010101000b, start_second_count_lo = 1100000b, end_
second_count_hi = 0000000000000000111111010b, start_
second_count_lo = 0100000b. This value is TIME_SCHE
Just write to the DULE register. For the sake of clarity, BUS_TIME is set to 0 o'clock on October 10th. Here, 40 Mbps corresponds to 2500d [BWU]. Therefore, request_bw = 0100111000100b.

At this time, in s3, if it is assumed that the currently used band and channel are continuously used until the reservation is executed, the remaining amount of the band when the reservation is executed is 2415d-25.
00d = -85d [BWU]. That is, if the reservation is executed, it can be seen that the bandwidth is insufficient. Therefore, s
From 3 to s7, the isochronous transmission overlaps at the reserved time, so the control means (not shown) of the STB 5 warns (notifies) the user that the desired isochronous transmission is not performed, using the notifying means (not shown). Yes (s7).

Here, the fact that the desired isochronous transmission is not performed means that the reservation operation is not normally performed or that the isochronous transmission currently used is interrupted by the reservation.

The user who receives the warning (notification) determines whether or not to make a reservation (s8). At s8, if the user recognizes that the currently used isochronous transmission will end by the reservation time, the TIME_SCHEDULE register is rewritten as shown in FIG. 7C (s9) to complete the reservation. (S5), the process ends. If the user who receives the warning gives up the execution of the reservation in s8, the reservation is canceled (s6), and the process ends.

The above processing is as shown in the conceptual diagram shown in FIG. FIG. 8 is a conceptual diagram of a reservation table showing a change over time of isochronous transmission in the bus system 1. FIG. 8 (A) shows the above-mentioned “(1) When the bandwidth used for timer recording is small”, and the AV-HDD 2 to D are transferred from 4 o'clock to 10 o'clock on October 10 for four hours.
While dubbing to VCR3, STB5 to AV-H
This indicates that timer recording is being performed on DD2. Here, the dubbing from the AV-HDD 2 to the DVCR 3 is 5
Suppose you spend from 10 to 10 pm. FIG. 8B shows the above-mentioned “(2) When the bandwidth used for timer recording is large”, and AV-H started from 5 o'clock on October 10.
This indicates that the dubbing from the DD2 to the DVCR3 is interrupted at 6 o'clock because the timer recording starts, and the timer recording from 6 o'clock to 18 o'clock is normally performed.

BANDWIDTH_AVAL in the above processing
The transitions of the ABLE register and the CHANNELS_AVAILABLE register are as follows. FIG. 9 is a diagram showing transitions of the BANDWIDTH_AVALABLE register and the CHANNELS_AVAILABLE register provided by the IRM for the IEEE 1394 serial bus. FIG. 9A shows the IRM BANDWIDTH_AV in the above-mentioned “(1) When the bandwidth used for timer recording is small”.
It shows changes in the ALABLE register and the CHANNELS_AVAILABLE register. From 0 o'clock to 5 o'clock on October 10, the values of these registers remain the initial values. In this embodiment, the upper 32 bits of the CHANNEL SAVAILABLE register, channels_available_hi, are not described because they remain unchanged as initial values.

Dubbing from the AV-HDD 2 to the DVCR 3 starts at 5 o'clock on October 10. Since 40 Mbps bandwidth is used on channel 0, bw_remaining = 4915d-2500
d ＝ 2415d [BWU] （＝ 0100101101111b）, channels_availab
le_lo = 11111111111111111111111111111111110b is rewritten to start isochronous transmission. At this time, the end time of dubbing is unknown. Further, rewriting of these two registers may be performed by any node on the bus. It is not always necessary for the PC, which is the node with physical_ID = 000000b, to do so.

Subsequently, since timer recording for the AV-HDD2 has started from the first STB 105 which made a reservation before 6:00 on October 10, the AV-HDD2 starts from 6:00.
To DVCR3 and STB5 to AV-H
Timer recording for DD2 proceeds simultaneously. That is,
40 Mbps band is used for channel 0 and 25 Mbps band is used for channel 1, so bw_remaining = 4915
d-2500d-1563d = 852d [BWU] (= 0001101010100b), chann
els_available_lo = 11111111111111111111111111111100
It will be rewritten as b.

By the end of dubbing at 10 o'clock on 10th October, 25 Mb from 10:00 to 18:00
bw_remaining because the ps band is used on channel 1
＝ 4115d-1561d ＝ 2352d [BWU] (＝ 0110100011000b), chan
nels_available_lo = 1111111111111111111111111111110
It will be rewritten as 1b.

After 18:00 on October 10, the bus is not used, so the BANDWIDTH_AVAILABLE register and CHANNELS_AV
The ALABLE register is reset to the initial value. At the end of the reserved time, req of the corresponding TIME_SCHEDULE register
It is necessary to rewrite uest_bw to 0000000000000b.

Next, FIG. 9B shows the IRM in "(2) When the bandwidth used for timer recording is large".
BANDWIDTH_AVAILABLE register and CHANNELS_AVAILABLE
Indicates a register change. From 0 o'clock to 5 o'clock on October 10, the values of these registers remain the initial values.

Dubbing from the AV-HDD 2 to the DVCR 3 starts at 5 o'clock on October 10. Since 40 Mbps bandwidth is used on channel 0, bw_remaining = 4915d-2500
d ＝ 2415d [BWU] （＝ 0100101101111b）, channels_availab
le_lo = 11111111111111111111111111111111110b is rewritten to start isochronous transmission. At this time, the end time of dubbing is unknown. Further, rewriting of these two registers may be performed by any node on the bus. It is not always necessary for the PC, which is the node with physical_ID = 000000b, to do so.

Next, the user changes the STB 5 to the AV-HDD.
Schedule timer recording for 2 before 6:00 on October 10. At this time, if the dubbing is continued after 6 o'clock, the band will be insufficient, and the dubbing or timer recording will be impossible. Therefore, the user is warned when making a reservation. Here, the user finishes dubbing at 6:00 and timer recording is performed from 6:00 to 18:00. In other words, from 6th October to 6pm
Until then, the bandwidth of 40 Mbps is used for channel 1, so bw_remaining = 4015d-2500d = 2415d [BWU] (= 01001
01101111b), channels_available_lo = 111111111111111
It will be rewritten as 11111111111111101b.

After 18:00 on October 10, the bus is not used, so the BANDWIDTH_AVAILABLE register and CHANNELS_AV
The AILABLE register is reset to the initial value. In addition, when the reserved time ends, the r of the corresponding TIME_SCHEDULE register
equest_bw needs to be rewritten to 0000000000000b.

As described above, according to the embodiment of the present invention, the deficiency of the timer recording reservation management method using the TIME_SCHEDULE register in the conventional TSM is improved, and the isochronous transmission whose end time is not clear is another isochronous transmission. When the reservation times of 1 and 2 overlap, it is determined whether or not both isochronous transmissions can be executed. Then, if either of the isochronous transmissions may become impossible, the user will be warned, so that the reservation management including future time will be maintained without any confusion to the user while maintaining compatibility with the conventional configuration. It is possible to

In the present embodiment, the warning issued to the user when the bands or channels are overlapped is preferably such that a warning screen is displayed on the monitor and a warning lamp is lit on the operation panel of the device, but isochronous transmission is accurate. Any means can be used as long as the user can be made aware that it may not be executed.

Further, in the case where the user ignores or does not notice the warning issued to the user when the bands or channels overlap, it is preferable that the upper application determines the priority and performs an appropriate process. .

Further, in the description of the embodiment, IEEE13
Although the 94 serial bus is used, another bus may be used as long as it can perform transmission with a secured transmission band and transmission channel.

[0065]

According to the present invention, the following effects can be obtained.

(1) When the end time of the data communication currently being performed is unknown, the data communication currently being performed is also performed after the predetermined time in order to determine whether or not the data communication to be performed after the predetermined time is possible. Since it calculates the transmission bandwidth and manages the data communication performed between multiple devices via the serial bus, it is also possible to support isochronous transmission that does not set the start time or end time.
The user can use each node without confusion. Further, reservation management including future time can be performed while maintaining compatibility with the conventional configuration.

(2) If the data communication currently being carried out is also carried out after the predetermined time, the data communication carried out after the predetermined time may be impossible due to the transmission bandwidth. To inform you that there is a possibility that
The user can know in advance the state of the serial bus when data communication is performed after a predetermined time.

(3) When it is informed that there is a possibility that it will be impossible due to the transmission bandwidth, the current data communication is continued and the data communication is reserved after a predetermined time. By being selectable, the user
If there is a possibility that it will be impossible to perform data communication after a predetermined time, you can select the data communication to be executed after the predetermined time, and the user can manage reservations including future time without confusion You can

(4) Since data communication performed between a plurality of devices is performed via a serial bus conforming to the IEEE 1394 standard, isochronous transmission is used to transmit a video signal, an audio signal, etc. in real time. Can be transmitted.

(5) If the end time of the data communication currently being performed is unknown, the serial bus management device calculates the transmission bandwidth assuming that the data communication currently being performed is also performed after a predetermined time. Then, the data communication performed via the serial bus between the plurality of devices is managed by using the control means that determines whether or not the data communication to be performed after the predetermined time period, so that the isochronous transmission without the start time or the end time is determined. It is also possible for the user to use each node without confusion. Further, reservation management including future time can be performed while maintaining compatibility with the conventional configuration.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a system bus including a node having a serial bus management device according to an embodiment of the present invention.

[Fig. 2] BANDWIDTH_AVAILABL in IEEE1394
It is a bit configuration diagram of an E register.

[Fig. 3] CHANNELS_AVAILABLE in IEEE 1394
It is a bit block diagram of a register.

FIG. 4 is a bit configuration diagram of a TIME_SCHEDULE register.

FIG. 5: BUS_TI in the IEEE 1394 serial bus
FIG. 6 is a bit configuration diagram of the ME register.

FIG. 6 is a flowchart illustrating an operation of a system including a node having a serial bus management device according to an exemplary embodiment of the present invention.

FIG. 7 is a bit configuration diagram of a TIME_SCHEDULE register for explaining a reservation operation.

FIG. 8 is a conceptual diagram of a reservation table showing a change over time of isochronous transmission in the bus system 1.

FIG. 9 is a BANDWIDTH_AVALABLE register and CHANNELS_A provided by the IRM for the IEEE 1394 serial bus.
It is a figure showing the change of a VAILABLE register.

FIG. 10 is a block diagram showing a configuration of a node having a conventional serial bus management device.

FIG. 11 is a block diagram showing a configuration of a bus system including a node having a conventional serial bus management function (TSM).

FIG. 12 is a state diagram of IEEE 1394 isochronous transmission.

[Explanation of symbols]

1,101-bus system 2,102-AV-HDD 3,103-DVCR 4,104-PC 5,105-STB 6,106,116-IEEE1394 serial bus 111-CPU 112-System Controller 113-Clock 114-memory 115-Serial Bus Controller

Claims (5)

[Claims] 1. In a serial bus management method for managing data communication performed between a plurality of devices via a serial bus, when the end time of the current data communication is unknown,
A serial bus management method, characterized in that the transmission bandwidth is calculated assuming that the data communication currently being carried out is also carried out after a predetermined time, and whether or not the data communication to be carried out after the predetermined time is permitted. 2. When the calculated transmission bandwidth after the predetermined time has a possibility that data communication cannot be performed after the predetermined time, the fact is notified. Serial bus management method described in. 3. The serial bus according to claim 2, wherein when the notification is given, it is possible to select between continuing the data communication currently being performed and reserving the data communication performed after a predetermined time. Management method. 4. The serial bus is IEEE1394
The serial bus management method according to any one of claims 1 to 3, wherein the bus is a standard-compliant bus. 5. In a serial bus management device for managing data communication performed between a plurality of devices via a serial bus, when the end time of the data communication currently being performed is unknown,
Serial bus management characterized by comprising control means for calculating the transmission bandwidth assuming that the data communication currently being carried out is carried out after a predetermined time and judging whether or not the data communication to be carried out after the predetermined time. apparatus.