JP3502359B2 - Communication control method and communication control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication control method and a communication control device, and more particularly to a communication control method and a communication control device for performing high speed serial communication.

[0002]

2. Description of the Related Art Conventionally, IEEE 139 has been established as an international standard for high-speed serial communication systems.
According to the four standards, when transferring a data packet on a bus to which a plurality of devices (nodes) are connected, isochronous transfer is performed after arbitration of bus acquisition in order to transfer data from node to node. Data transfer methods include isochronous transfer and asynchronous transfer, but the first 100 μs (MAX) in a predetermined period (125 μs).
Is used as an area for isochronous transfer, and the remaining period (for example, 25 μs) is used as an area for asynchronous transfer. Since this isochronous transfer has a higher priority than the asynchronous transfer, the asynchronous transfer cannot be performed while the isochronous transfer is being performed.

According to the above-mentioned standard, it is necessary to acquire a bandwidth and a channel (these are collectively referred to as a resource) required on the IEEE 1394 bus (hereinafter simply referred to as a bus) in order to perform isochronous transfer. When such a bus is used in a home network or the like, several tens (63 at maximum) of devices (nodes) are connected to one bus, so that the isochronous resource manager (I
It is necessary to efficiently use limited resources by using RM).

FIG. 9 is a control operation flow chart in the communication control device for explaining an example of the conventional art. As shown in FIG. 9, in the conventional acquisition of an isochronous resource, first of all, bus reset, that is, identification of a tree that determines the hierarchical relationship between nodes, root node, node ID
After (self) identification, IRM, etc. are determined, normal packet transfer (isochronous, asynchronous) is started.

Then, the node performing the isochronous transfer reads the currently usable bandwidth from the bandwidth effective register of the IRM (step A1) and compares it with the requested bandwidth, that is, the bandwidth desired to be acquired (step A2). ). If the read bandwidth is larger than the desired bandwidth, the bandwidth is acquired (step A
After performing 3), acquire channels (Step A)
4). On the other hand, if the read bandwidth is smaller than the desired bandwidth, it is judged whether or not the required bandwidth can be reduced (step A7). If YES, the bandwidth to be obtained is reduced. Then, the process returns to step A1 again to make a request. If it is not possible to reduce the required bandwidth in step A7, after a certain period of time, isochronous resources are acquired again with the same bandwidth as the previously requested bandwidth (step A8).

[0006]

SUMMARY OF THE INVENTION In the conventional isochronous resource acquisition method described above, the isochronous
Since there is no means for releasing the node that does not perform isochronous transfer by only acquiring resources, various devices (nodes) are connected to the bus, and isochronous resources (bandwidth and channel) are repeatedly acquired and released. Then, depending on the failure of the release procedure or the state of the device, there are cases where the isochronous resource is not used while the isochronous resource is secured without performing the release procedure.

Therefore, the conventional resource acquisition method has a drawback that the isochronous resource is reduced or the isochronous resource cannot be acquired at all.

An object of the present invention is to provide a communication control method and a communication control device capable of removing the generation of unused resources which are reserved on the bus and efficiently using the limited resources. is there.

[0009]

According to the communication control method of the present invention, a bus connected to a plurality of devices is connected to the bus in order to acquire resources consisting of a bandwidth and a channel required for isochronous transfer. Done P
HY layer and LI as an upper layer of the PHY layer
A transaction layer that transfers data between the NK layer and the LINK layer; and a resource acquisition unit that is connected between these layers to control the acquisition processing of the resources and acquire free resources. An unused resource searching unit that searches for acquired unused resources of the plurality of devices based on the output of the resource acquiring unit, and an unused resource that releases the unused resource according to a search result of the unused resource searching unit A resource processing device provided with a releasing means, and the resource processing device controls each of the means by software or hardware to acquire the plurality of devices when the resource is not available when the resource is acquired. Search for acquired unused resources, and if the acquired unused resources are found as a result, To be configured to re-acquire the resource after performing release processing of the acquisition has been unused resources.

Further, the software executes a first step of reading the value of the bandwidth effective register from the isochronous resource manager which manages the resource, and a transfer of the value and the data read by the first step. The second step of comparing the magnitude with the bandwidth required by the device to be sought, the third step of acquiring the bandwidth when there is the bandwidth required in the second step, and the third step of A fourth step of acquiring a channel following the step; and a fifth step of reading the value of the channel valid register from the isochronous resource manager when there is no bandwidth required in the second step, As a result of reading in the fifth step, whether there is an unused channel among resources acquired by other devices. A sixth step of determining, when said did unused channel in the sixth step,
Seventh, determining whether the required bandwidth can be reduced
And in the seventh step, when the required bandwidth cannot be reduced, an eighth step of requesting the same bandwidth again after a predetermined time elapses and ending the processing, and the sixth step When there is an unused channel, the bus is reset and the first
And the ninth step of returning to the step of (4), and when it is determined in the seventh step that the required bandwidth can be reduced, the procedure returns to the first step as in the case of the ninth step. It is formed to repeat the process.

Further, the resource processing device in the communication control method is provided with a resource remaining amount detecting means for detecting the remaining amount of the resource at regular time intervals, searches for the resource decrease amount at regular time intervals, and When the number of resources becomes low, the resource remaining amount detecting unit and the unused resource searching unit search the unused resources, and when there are the unused resources, the resource releasing process is performed.

Further, the resource processing device in the communication control method is provided with a resource time limit detecting means for detecting a use time limit of the resource, and the resource is not required to be extended by the use deadline of the resource, and the resource can be used. Is unused, the resource time limit detecting means and the unused resource searching means search the unused resource, and if there is the unused resource, the unused resource
It is formed so as to perform the release processing of the space.

The software in the communication control method writes the value of the bandwidth valid register from the isochronous resource manager that manages the resource and issues the lock transaction.
And a second step for determining whether or not the writing in the first step is successful, and a second step
And a third step of acquiring a channel when the writing of the data is successful in the step, and the channel valid register from the isochronous resource manager when the writing of the data is unsuccessful in the second step. And a fifth step of determining whether or not there is an unused channel among resources acquired by other devices as a result of being read in the fourth step, and the fifth step. In the step of determining whether the required bandwidth can be reduced when there is no unused channel, and when the required bandwidth cannot be reduced in the sixth step, a predetermined step is performed. After a lapse of time, the seventh step of requesting again with the same bandwidth and ending the processing, and the unused step in the fifth step. When there is tunnel includes a first said bus reset is generated returns to the first Step 8
And the process is repeated in the same manner as in the eighth step when it is determined in the sixth step that the required bandwidth can be reduced. To be done.

Further, the communication control device of the present invention is a PHY.
An unused resource detection circuit connected between the layer and the transaction layer and having a link layer function and a resource processing function, wherein the unused resource detection circuit is
An isochronous data receiving circuit for receiving isochronous data, a FIFO circuit for outputting the received data from the isochronous data receiving circuit to the outside, and an isochronous data receiving circuit for the isochronous data receiving circuit.
An all-channel number storage circuit that stores all channel numbers based on data, a reception channel setting register that outputs the isochronous data to the isochronous data receiving circuit, and a channel register value of the isochronous resource manager A channel register value storage circuit of the isochronous resource manager, which compares the values of the channel register value storage circuit and the all channel number storage circuit, and outputs a mismatch signal when they do not match,
The CPU is configured to control the FIFO circuit, receive the data of the FIFO circuit and the mismatch output from the comparison circuit, and output the data for receiving channel setting to the receiving channel setting register.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, in a system for acquiring a bandwidth and a channel (resource) necessary for performing isochronous transfer, an unused resource which is secured but not isochronous transfer is searched for. The purpose of the present invention is to realize a communication control method and a communication control device which release resources to the unused resources to eliminate the generation of unused resources and efficiently use limited resources.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a communication control device for explaining the first embodiment of the present invention. As shown in FIG. 1, this embodiment is based on the IEEE 1394 standard (19
PHY layer 1 as a physical layer that serves as a physical interface of the bus for acquisition of bus resources defined by the 1995 standard), and LINK layer 2 that performs data transmission / reception and cycle control as an upper layer thereof. It has a transaction layer 4 that determines a procedure for performing transactions such as read, write, and lock, and a resource processing device 3 that operates under program control and transfers resource data to each of these layers. Here, one node is represented as a block configuration. Of the plurality of nodes, the node that is the root of the tree or the node closest to this root node is the isochronous resource manager (IRM).

The resource processing device 3 includes a resource acquisition unit 31, an unused resource search unit 32, and an unused resource release unit 33. In particular, the resource acquisition unit 31 is a PHY layer 1 and a LINK layer 2. Through the transaction layer 4, the bus bandwidth and channel acquisition request is output to the IRM that manages the resource.

If the bandwidth to be acquired is larger than the currently available bandwidth, the resource acquisition means 3
The unused resource searching means 32 searches for an unused resource in accordance with the request instruction output from 1. If there is an unused resource as a result of the search, the unused resource searching means 32 controls the unused resource releasing means 33 to cause the above-mentioned bus reset. In the resource processing device 3, when a bus reset occurs, the node connected to the bus interface (not shown) performs a resource reacquisition process. As a result, the node that has failed to release the resource does not reacquire the resource, so the unused resource is released, and the unused resources are used by other nodes. It will be possible.

In this way, the node that resets the bus releases unused resources and enables efficient use of the resources.

More specifically, the above-mentioned resource acquisition will be described. The resource acquisition means 31 includes a bandwidth effective register and a channel effective register of an IRM installed in a serial bus management (SBM) not shown. On the other hand, a read transaction is performed. At this time, if the bandwidth of the bandwidth valid register of the IRM is larger than the requested bandwidth, the lock transaction is used to acquire the bandwidth and the channel.

It should be noted that the isochronous resource manager (IRM) compatible node and the bus management compatible node must implement the above-mentioned bandwidth effective register.
This register can be rewritten only by the lock transaction. Moreover, this register is provided for the purpose of allocating and deallocating the isochronous bandwidth by the user of the isochronous resource. In particular, this register value indicates the currently available bandwidth. ing.

When the own node is the IRM, it reads the register of itself or performs the lock transaction of the compare swap to obtain the bandwidth and the channel. Here, the compare swap transmission of the lock transaction described above is one of the transmission / reception methods stipulated in the above-mentioned IEEE 1394-1995 standard. That is, the transmission side transmits the value of the register of the other party (request arg) and the value of which the register is desired to be changed (request data). On the other hand, the receiving side has its own register value (memory
data) and the request arg value are compared, and when they match, the register value of its own is requested.
Rewrite to the value of data. Furthermore, the transmission side returns the memory data before being rewritten as a response.

Next, the unused resource searching means 32 is
If the bandwidth of the IRM bandwidth valid register is smaller than the required bandwidth, the channel currently performing isochronous transfer is compared with the channel acquired by the channel valid register to determine the unused channel. Search for. Further, the unused resource releasing means 33 outputs a bus reset generation request for resource reacquisition when there is an unused resource as a result of the search by the unused resource searching means 32, and thereby the unused resource is issued. Open up.

The above-described operation has been described with respect to the functional operation of each means in the resource processing device 3 upon resource acquisition. Next, the overall control operation will be described with reference to FIGS.
Will be described with reference to.

FIG. 2 is a flow chart for explaining the control operation in FIG. As shown in FIG. 2, when isochronous transfer is desired, the resource acquisition unit 31 reads the value from the bandwidth effective register of the IRM (step A1), and the bandwidth of the value of the bandwidth effective register is larger than the requested bandwidth. It is checked whether or not the width is larger (step A2). As a result, when the bandwidth of the value of the bandwidth valid register is larger than the requested bandwidth, that is, when the free bandwidth is larger, the bandwidth is acquired (step A3) and then the channel is acquired. By doing (step A4), the resource acquisition is completed. On the other hand, when the bandwidth of the value of the bandwidth effective register is smaller than the requested bandwidth, the unused channel search means 32 reads the value of the channel effective register of the IRM (step A5), and the value is currently on the bus. The output isochronous channel is compared to search for an unused channel (step A6). If there is an unused channel, the resource releasing means 33 outputs a bus reset generation request (step A9) and returns to step A1 to repeat the resource acquisition operation. Also in this step A6, if there is no unused channel, it is checked whether or not the requested bandwidth can be reduced (step A7). If the bandwidth can be reduced, the requested bandwidth is reduced. , And returns to step A1 to acquire bandwidth and channel again. Conversely, if the bandwidth cannot be reduced in step A7,
After a certain period of time, the acquisition request is output again with the same bandwidth. When it is found in step A7 that there is no acquired resource, the acquisition request is output again with the same bandwidth (step A8), and the resource acquisition operation is ended.

Next, the resource releasing operation when there is no free bandwidth, that is, in steps A5 to A9 of FIG. 2, will be described using a specific example.

FIG. 3 is a timing chart focusing on the resource acquisition node and the IRM for more specifically explaining the operation in FIG. As shown in FIG. 3, a node wishing to acquire a resource issues a read transaction as a usable bandwidth read request (READ request) to the bandwidth effective register of the IRM (step D
1) Confirm the currently available bandwidth from the register value response (step D2). As a result of this response, when there is no free bandwidth, the read transaction is again issued to the channel valid register (step D3), and the channel is read, that is, the register value is acquired (step D4).

Then, in the node which wants to acquire the resource, the channel in which the isochronous transfer is performed on the IEEE 1394 bus is compared with the channel in which the channel valid register value is acquired, and the used channel is detected (step D5). ). In the channel valid register, if there is a channel that has acquired a channel but has not been subjected to isochronous transfer, that is, an unused channel (step D6), a node that wants to acquire resources issues a bus reset generation request ( Step D7). When a bus reset is generated from such a node to the IRM, the resource is released and each node on the bus reacquires the resource (step D8).

However, since the node that has failed to release the resource does not reacquire the resource, the resource can be freed. When this resource becomes free and the requested bandwidth becomes available, issue a lock transaction to the bandwidth valid register (step D
9) After confirming the usable bandwidth by the response from the IRM (step D10), the bandwidth is acquired (step D11). Next, the resource acquisition node issues a lock transaction to the IRM channel valid register to acquire the channel (step D1).
2). Here, when the own node is the IRM, the access to the above register performs reading and writing to the own register instead of issuing the transaction processing. The above is the procedure for resource acquisition.

FIG. 4 is a block diagram of a communication control device for explaining the second embodiment of the present invention. As shown in FIG. 4, this embodiment includes a PHY layer 1, a LINK layer 2, a transaction layer 4, and a resource processing device 5 as in the first embodiment described above. . This resource processing device 5 is, in addition to the resource processing device 3 in the first embodiment, a resource remaining amount detecting means 3 for detecting a resource remaining amount when searching for an unused resource.
It is configured by adding 4. This resource remaining amount detecting means 3
4 is connected to the unused resource search means 32, reads the values of the bandwidth effective register and the channel effective register, and monitors the remaining amount of resources at regular time intervals. That is, the resource remaining amount detecting means 34 monitors the resource at a constant time interval, and when the resource remaining amount is low, the unused resource releasing means 33 is driven through the unused resource retrieving means 32 so as not to operate. Release used resources.

FIG. 5 is a flow chart for explaining the control operation in FIG. As shown in FIG. 5, first, the value of the bandwidth effective register is repeatedly read at constant time intervals (step B1), and it is determined whether the remaining resource amount is small or not based on the read value (step B2). Then,
As a result of checking the remaining amount of resources, when the remaining amount of resources is low, the value of the channel valid register is read at a constant time interval (step B3), and it is confirmed whether or not there is an unused channel with the read value. Yes (Step B
4). As a result, if there is an unused channel, a bus reset is generated (step B5), and one detection process when the remaining amount becomes small is ended.

In short, here, it is repeatedly monitored whether or not the resource remaining amount is low at a constant time interval, and when there is an unused channel when the resource remaining amount is low, a bus reset is generated. Then, the bus is released once. Then, the same monitoring is repeated after a predetermined time.

As described above, this embodiment is different from the above-described first embodiment in that the resource is regularly managed. By regularly monitoring the amount of resource reduction, it is possible to prevent the unnecessary reduction of unused resources in a state that is almost constant, and to efficiently control devices (nodes) connected to the bus. Resources such as bandwidth and channels can be used with high efficiency.

FIG. 6 is a block diagram of a communication control device for explaining the third embodiment of the present invention. As shown in FIG. 6, this embodiment includes a PHY layer 1, a LINK layer 2, a transaction layer 4, and a resource processing device 6 as in the first embodiment described above. . This resource processing device 6 is configured by adding a resource time limit detecting means 35 for detecting a time limit of a resource at the time of searching for an unused resource in addition to the resource processing device 3 in the first embodiment. The resource time limit detecting means 35 is connected to the unused resource searching means 32, reads the values of the bandwidth effective register and the channel effective register, and monitors the effective time of the resource. That is, the resource time limit detecting means 35 is a method of providing an effective time for a resource and releasing the resource when there is no request for extension of the effective time from a node that has acquired the resource.

In short, this embodiment is the same as the first embodiment described above.
The embodiment is different from the above embodiment in that an effective time is set in a resource. Specifically, if there is no resource extension request after a certain period of time, it is determined that the resource is an unused resource and the resource is released. Equipment (node)
Can be efficiently controlled and resources can be used more effectively.

FIG. 7 is a control operation flowchart in the communication control device for explaining the fourth embodiment of the present invention. The above-described first embodiment was based on the 1995 standard, but as shown in FIG.
Latest standard IEEE1394a-2000 (2000
Year). According to this standard, IRM
It is not necessary to read the value of the bandwidth valid register of, and a lock transaction can be issued and directly written to the resource to be acquired.

That is, set the bandwidth to be acquired,
A lock transaction is issued to the bandwidth valid register of the IRM (step C1), and then it is determined whether or not the lock transaction is successful (step C2). Here, if the writing to the register is successful, the channel is acquired (step A4) and the process is ended. The process from step A4 and the reading of the value of the channel valid register (step A5) to the occurrence of the bus reset (step A9) is the same as the flow of FIG. 2 in the first embodiment described above, and therefore will be described. Is omitted.

According to the present embodiment, since it is not necessary to read the value of the bandwidth effective register of the IRM in advance, the control time for managing resources is shortened and the device ( Node) can be controlled more efficiently.

FIG. 8 is a block diagram of an unused resource detection circuit in the communication control device for explaining the fifth embodiment of the present invention. As shown in FIG. 8, the present embodiment is
Comprising the PHY circuit 100 and the unused resource detection circuit 200, the PHY circuit 100 is in the PHY layer 1 and the unused resource detection circuit 200 is in the LINK layer 2 and resources as compared with the block configuration of FIG. It corresponds to the processing device 3. In this detection circuit 200, an isochronous data reception circuit 210,
FIFO circuit 220 and reception channel setting register 2
30 corresponds to the link layer 2, and the other circuits except the CPU 260 correspond to the resource processing device 3. In addition, CP
The U 260 may be provided in any of the link layer 2, the resource processing device 3, and the transaction layer 4 in FIG. 1, but the circuit corresponding to the transaction layer 4 is omitted here.

The unused resource detecting circuit 200 includes an isochronous data receiving circuit 210 for receiving isochronous data and a FIFO for outputting the received data from the isochronous data receiving circuit 210 to the outside.
Circuit 220 and isochronous data receiving circuit 210
All channel number storage circuit 270 that stores all channel numbers based on the isochronous data of
Receive channel setting register 230 to be passed to
The IRM channel register value storage circuit 240 that stores the M channel register value is compared with the IRM channel register value storage circuit 240 and all channel number storage circuit 270 values, and outputs a mismatch signal when they do not match. It is composed of a comparison circuit 250 and a CPU 260 which controls the FIFO circuit 220 and receives the data of the FIFO circuit 220 and the mismatch output from the comparison circuit 250 and outputs the data for receiving channel setting to the receiving channel setting register 230. is doing.

First, the isochronous data receiving circuit 2
10 receives the isochronous data of the channel set by the receiving channel setting register 230. The isochronous data received by the isochronous data receiving circuit 210 is directly output to the external circuit and is also passed to the external circuit via the FIFO circuit 220. The all channel number storage circuit 270 is a circuit that is connected to the isochronous data receiving circuit 210 and acquires the channels of all isochronous data output on the bus. The IRM channel register value storage circuit 240 is a circuit for storing the value of the channel valid register. The comparison circuit 250 compares the data stored in the all channel number storage circuit 270, that is, the data of all channels output on the bus with I
The value of the channel valid register stored in the channel register value storage circuit 240 of the RM is compared, and when the values do not match, the CPU 260 is notified. As a result, it is possible to realize the same detection function as the unused resource detecting means 32 in the first embodiment described above.

Further, as mentioned above, IEEE1394
Since the resource release processing defined by the standard can be performed only by the node that has acquired the resource, bus reset is used as a means for releasing the resource. For this reason, the resource releasing method determined by the higher standard (protocol) of the IEEE 1394 standard can be used instead of the bus reset.

In short, in the above-described first to fourth embodiments, the detection of unused resources is detected by software, but as in the fifth embodiment, the detection of unused resources is detected by hardware. It is also possible to realize with.

[0044]

As described above, the communication control method and the communication control device of the present invention search for unused resources,
When there is an unused resource, a bus reset is generated to reacquire the resource, and the unused resource is released, thereby releasing the unused resource but not releasing it. As a result, it is possible to release resources that could not be released, thereby eliminating the occurrence of unused resources and effectively using the resources.

[Brief description of drawings]

FIG. 1 is a block diagram of a communication control device for explaining a first embodiment of the present invention.

FIG. 2 is a flow chart for explaining a control operation in FIG.

FIG. 3 is a timing chart centered on a resource acquisition node and an IRM for explaining the operation in FIG. 2 more specifically.

FIG. 4 is a block diagram of a communication control device for explaining a second embodiment of the present invention.

FIG. 5 is a flowchart for explaining the control operation in FIG.

FIG. 6 is a block diagram of a communication control device for explaining a third embodiment of the present invention.

FIG. 7 is a control operation flowchart in the communication control device for explaining the fourth embodiment of the present invention.

FIG. 8 is a configuration diagram of an unused resource detection circuit in a communication control device for explaining a fifth embodiment of the present invention.

FIG. 9 is a control operation flow chart in the communication control device for explaining an example of the related art.

[Explanation of symbols]

1 PHY layer 2 LINK layer 3 Resource processing device 4 Transaction layer 31 Resource acquisition means 32 Unused resource search means 33 means for releasing unused resources 34 Resource remaining amount detecting means 35 Resource time limit detection means 100 PHY circuit 200 Unused resource detection circuit 210 Isochronous data receiving circuit 220 FIFO circuit 230 Receive channel setting register 240 IRM channel register value storage circuit 250 comparison circuit 260 CPU 270 All channel number storage circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takaji Hori 1-403, Kosugi-cho, Nakahara-ku, Kawasaki-shi, Kanagawa 403-353 NEC IC Microcomputer System Co., Ltd. (56) Reference JP 2000-115198 (JP, A) ) JP 2001-94583 (JP, A) JP 11-275122 (JP, A) JP 7-38579 (JP, A) JP 2001-127768 (JP, A) JP 2001-77823 (JP , A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04L 12/28 200 H04L 12/40 H04L 29/08

Claims (6)

(57) [Claims] 1. A PHY layer connected to the bus and an upper layer of the PHY layer when acquiring a resource including a bandwidth and a channel required for isochronous transfer on a bus to which a plurality of devices are connected. And a transaction layer for transferring data between the LINK layer and the LINK layer, and is connected between each of these layers to control acquisition processing of the resource and acquire a resource for acquiring a free resource. Means, an unused resource searching means for searching the acquired unused resources of the plurality of devices based on the output of the resource acquiring means, and an unused resource releasing means based on the search result of the unused resource searching means. A resource processing device having a used resource releasing unit,
When there is no free resource when acquiring the resource, the resource processing device controls each unit by software or hardware to search for acquired unused resources of the plurality of devices, and as a result, A communication control method, wherein when there is an acquired unused resource, the acquired unused resource is released, and then the resource is acquired again. 2. The software comprises a first step of reading a value of a bandwidth effective register from an isochronous resource manager managing resources, and a transfer of the value and data read by the first step. The second step of comparing the magnitude with the bandwidth required by the device to be sought, the third step of acquiring the bandwidth when there is the bandwidth required in the second step, and the third step of A fourth step of acquiring a channel following the step; and a fifth step of reading the value of the channel valid register from the isochronous resource manager when there is no bandwidth required in the second step, As a result of reading in the fifth step, it is determined whether or not there is an unused channel among the resources acquired by other devices. A sixth step of determining, and when there is no unused channel in the sixth step,
Seventh, determining whether the required bandwidth can be reduced
If the required bandwidth cannot be reduced in the seventh step, an eighth step of requesting the same bandwidth again after a lapse of a predetermined time and ending the processing, and the sixth step When there is an unused channel, the bus is reset and the first
If it is determined in the seventh step that the required bandwidth can be reduced, the procedure returns to the first step as in the ninth step. The communication control method according to claim 1, wherein the process is repeated. 3. The resource processing device is provided with a resource remaining amount detecting means for detecting the remaining amount of the resource at regular time intervals, searches for the resource decrease amount at regular time intervals, and when the resource becomes low, The communication control method according to claim 1, wherein the unused resource is searched by the resource remaining amount detecting means and the unused resource searching means, and release processing of the resource is performed when there is the unused resource. 4. The resource processing device is provided with a resource time limit detecting means for detecting a use time limit of the resource, and when there is no request for extension by the use deadline of the resource and the resource is not used. 2. The communication according to claim 1, wherein the resource time limit detecting means and the unused resource searching means search for the unused resource, and release the unused resource when there is the unused resource. Control method. 5. The software comprises a first step of issuing a lock transaction by writing a value of a bandwidth effective register from an isochronous resource manager that manages resources, and a write in the first step. Second to judge whether it succeeded
And a third step of acquiring a channel when the data writing in the second step is successful, and the isochronous data acquisition step when the data writing in the second step is unsuccessful. A fourth step of reading the value of the channel valid register from the resource manager, and a fifth step of judging whether or not there is an unused channel among the resources acquired by another device as a result of the reading in the fourth step. Steps of
A sixth step of determining whether the required bandwidth can be reduced when there is no unused channel in the fifth step, and the required bandwidth cannot be reduced in the sixth step. Sometimes, after a lapse of a predetermined time, a seventh step of requesting the same bandwidth again and ending the processing, and when there is an unused channel in the fifth step, the bus is reset and the first channel is generated. And an eighth step returning to the step of
5. The communication control method according to claim 1 or 4, wherein when it is determined that the required bandwidth can be reduced in the step of, the process returns to the first step and the process is repeated, as in the case of the eighth step. . 6. An isochronous data reception circuit comprising an unused resource detection circuit connected between a PHY layer and a transaction layer and having a link layer function and a resource processing function, wherein the unused resource detection circuit receives isochronous data. A circuit, a FIFO circuit for outputting the received data from the isochronous data receiving circuit to the outside, an all channel number storage circuit for storing all channel numbers based on the isochronous data of the isochronous data receiving circuit, and the isochronous A receiving channel setting register for outputting data to the isochronous data receiving circuit, and a channel for the isochronous resource manager storing the channel register value of the isochronous resource manager The register register value storage circuit, the channel register value storage circuit and the all channel number storage circuit, and outputs a mismatch signal when they do not match, and the FIFO circuit is controlled and the FIFO circuit CP for receiving data and a mismatch output from the comparison circuit and outputting data for setting a reception channel to the reception channel setting register
A communication control device characterized by being configured with U.