JPH1115779A - Bus control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify distribution between bus masters and a bus controller, to provide efficient data transfer and to construct a flexible system. SOLUTION: A bus controller 20 which arbitrates a use request for a common bus 1 sends common information ACKINFO that includes a bus use enabling signal for a bus master that is allowed to use the bus 7 and an identifier of the bus master to plural bus masters 10-1 to 10-n by using one signal line 50a. Each bus master 10-1 to 10-n that receives it recognizes which bus master is given the use permission of the bus 1 based on the identifier of bus master which is included in the information ACKINFO.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bus control system for arbitrating a common bus shared by a plurality of bus masters when the use requests conflict with each other.

[0002]

2. Description of the Related Art A bus control system is used in a computer system or the like.
Memory and I / O (Input / Outp
ut) A slave device such as a device and a CPU (Central Processing Unit) or DM for transferring data between the devices.
It comprises a bus master such as an A (Direct Memory Access) controller and a bus controller that arbitrates requests for using a common bus from a plurality of bus masters. Data transfer between each device includes transfer between slave devices, between a bus master and a slave device, or between bus masters.

As an example of such a bus control system, as shown in FIG. 6, a plurality of bus masters 30-1 to 30-n
And the bus controller 40 are connected by bus use request signal lines 51-1 to 51-n and bus use permission signal lines 52-1 to 52-n, respectively. In this bus control system, each of the bus masters 30-1 to 30-n communicates with the bus controller 40 via the bus use request signal lines 51-1 to 51-n when trying to use the common bus. Request signal REQ1 ~
REQn is transmitted, and in this state, the bus controller 40 sends a bus use permission signal via the bus use permission signal lines 52-1 to 52-n.
Wait until ACK1 to ACKn are received. The bus masters 30-1 to 30-n that have received the bus use permission signals ACK1 to ACKn start data transfer between the devices using the common bus, and when the data transfer ends, the bus use request signal REQ1 ~
Stop sending REQn.

At this time, as shown in FIG. 7, the bus controller 40 transmits a bus use request signal REQ1 from a certain bus master 30-1 while the common bus is not used (period (g) in FIG. 7). When it is received (when the level changes from a high level to a low level), a bus use permission signal ACK1 is transmitted to the bus master 30-1 that has transmitted the bus use request signal REQ1,
Next, the state is maintained until the common bus becomes available.

[0005] Further, when a bus master request signal REQ1 is transmitted from another bus master 30-1 in a situation where a certain bus master 30-2 uses the common bus (period (h) in the figure), After waiting until the common bus becomes usable, the bus controller 40 transmits the use permission signal ACK1 to the other bus master 30-1.

When the bus use request signals REQ1 to REQn from the plurality of bus masters 30-1 to 30-n conflict (period (i) in the figure), the bus controller 40 sets a predetermined priority order. According to the bus use permission signal for the highest priority bus master 30-1 to 30-n at that time.
ACK1 to ACKn are transmitted.

Therefore, a bus master whose bus use has not been permitted or a bus master which has transmitted a bus use request signal in a situation where the common bus is being used has finished using the common bus by a bus master which has already been permitted to use the common bus. Until the priority set becomes effective.
It will keep waiting for the bus use permission signal from the bus controller 40.

However, the bus masters 30-1 to 30-n include those in which the urgency of the bus use request does not change and those in which the urgency of the bus use request changes in accordance with the operation status inside and outside the bus master. .

In a bus master in which the degree of urgency of a bus use request changes, if the state changes between when the bus use request signal is transmitted and after that, the bus master cannot fully wait for the bus use request signal from the bus controller 40. Data transfer between devices may not be performed correctly. For example, in a bus master that temporarily stores external data in a storage unit provided inside the bus master and then transfers the stored data using a common bus, the bus master waits for a bus use request signal from the bus controller 40. Further, when data is received from the outside, the storage area of the storage unit may be squeezed and an error may occur such that data transfer cannot be performed normally.

For this purpose, instead of performing arbitration in accordance with a predetermined priority, a bus controller capable of changing the setting of the priority by a well-known technique such as a round robin method may be used. Even if the priority order is changed, the priority order is not changed depending on the operation state inside and outside the bus master, so that the above-described problem such as occurrence of an error cannot be solved.

In order to solve such a problem, Japanese Patent Application Laid-Open No. Hei 5-151155 discloses that information such as the status and wait time of the common bus is transmitted to a bus master whose use of the common bus is not permitted. A system configured using a bus controller is disclosed. This will be described with reference to FIG. 8. In this system, the bus masters 31-1 to 31-1 that have transmitted the bus use request signals REQ1 to REQn
Of -n, the bus use permission signals ACK1 to ACKn are given to the bus masters that have permitted the use of the common bus, and the common bus information indicating the status and wait time of the common bus is given to the bus masters that have not permitted the use of the common bus. The bus controllers 41 transmit the signals STS1 to STSn (or WT1 to WTn) using the same bus signal lines 53-1 to 53-n, respectively.

Thus, in this bus control system,
The common bus information signals STS1 to STS1 to
Even if the bus master receives STSn (or WT1 to WTn), its common bus information signals STS1 to STSn (or WT1 to WTn)
(1 to WTn), the status and wait time of the common bus can be known.Therefore, after changing the priority, it is possible to transmit the bus use request signals REQ1 to REQn again and perform error processing inside the bus master. As a result, there is no occurrence of an error or the like due to a change in the operation state inside or outside the bus master.

[0013]

However, this bus control system requires bus signal lines 53-1 to 53-n corresponding to the number of bus masters 31-1 to 31-n.
In addition to complicating the wiring (circuit) configuration between the bus controllers 31-1 to 31-n and the bus controller 41, the following problems occur.

There is always one bus master permitted to use the common bus in the system. Therefore, when a plurality of bus masters 31-1 to 31-n are connected to the bus controller 41 and the bus use request signals REQ1 to REQn are transmitted from the respective bus masters 31-1 to 31-n, the bus controller 41 , Common bus information signals STS1 to STSn (or WT1 to WTn) for each of the bus masters other than the bus master that has permitted use of the common bus, ie, for each of the bus signal lines 53-1 to 53-n.
Must be sent. Therefore, the process for transmitting the common bus information signals STS1 to STSn (or WT1 to WTn) becomes complicated for the bus controller 41, and as a result, it hinders the improvement of the processing efficiency in the system. .

The bus controller 41 has a number of bus use request signal lines 51-1 to 51-1 corresponding to the bus masters 31-1 to 31-n.
An input port for 51-n and output ports for bus signal lines 53-1 to 53-n corresponding to the number of bus masters 31-1 to 31-n are required. Therefore, even if an attempt is made to add a new bus master in the system, it may not be possible to cope easily in some cases. Further, on the side of the bus masters 31-1 to 31-n, the bus use permission signals ACK1 to ACKn and the common bus information signal ST are transmitted by the bus signal lines 53-1 to 53-n.
Since S1 to STSn (or WT1 to WTn) are transmitted, a function to identify them is required, and a bus master that does not support them cannot be connected, resulting in versatility and expandability. Would be difficult to secure.

Accordingly, the present invention provides a bus controller that notifies the bus master of the status and wait time of the common bus to the bus master without complicating the wiring configuration and further improving the processing efficiency in the system. An object of the present invention is to provide a bus control system capable of realizing improvement. Further, the present invention provides a bus control system that can ensure versatility and expandability as a system even when the bus controller notifies the bus master of the status and wait time of the common bus. The purpose is to do.

[0017]

SUMMARY OF THE INVENTION The present invention is a bus control system devised to achieve the above object, and has one of the following two basic configurations. One is a bus control system including a common bus, a plurality of bus masters performing data transfer using the common bus, and a bus controller performing arbitration for a common bus use request from the plurality of bus masters. The bus controller uses one signal line commonly connected to the plurality of bus masters to transmit common information including a bus use permission signal to the bus master that has permitted use of the common bus by the arbitration and an identifier of the bus master. hand,
A common information transmitting unit for transmitting to each of the plurality of bus masters, wherein each of the plurality of bus masters includes:
When the common information is transmitted from the common information transmitting means, based on the identifier of the bus master included in the common information, which of the plurality of bus masters has been given permission to use the common bus. Is provided with permission recognition means for recognizing.

In the bus control system having the above configuration, when the use requests of the common bus from a plurality of bus masters conflict, the bus controller arbitrates for these requests. Then, the common information transmitting means of the bus controller transmits the common information including the bus use permission signal to the bus master that has permitted use of the common bus and the identifier of the bus master.
Each bus master is notified by transmitting using one signal line commonly connected to each bus master. On the other hand, in the bus master, the permission recognizing unit recognizes which bus master has been granted the use permission of the common bus based on the identifier of the bus master included in the transmitted common information. Therefore, even when the bus controller notifies each bus master of the arbitration result for the bus use request from each bus master and the information on the status of the common bus and the wait time at the time of the arbitration, the bus controller performs the arbitration. By including it in the common information, transmission can be performed by one signal line.

Another one of the two basic configurations is a common bus, a plurality of bus masters performing data transfer using the common bus, and arbitration for a common bus use request from the plurality of bus masters. And a bus controller that performs a bus use permission signal transmission unit that transmits a bus use permission signal only to a bus master that has permitted the use of the common bus by the arbitration. Apart from this, common information transmitting means for transmitting common information to each of the plurality of bus masters by using one signal line commonly connected to the plurality of bus masters is provided. is there.

In the bus control system having the above configuration, when a plurality of bus masters compete for use of the common bus, the bus controller arbitrates the requests, and the bus controller use permission transmitting means transmits the arbitration result to the bus controller.
The transmission of the bus use permission signal notifies the bus master permitted to use the common bus. At this time, the common information transmitting means of the bus controller uses one signal line commonly connected to each bus master, and uses, for example, the identifier of the bus master to which each bus master is permitted to use the common bus and the identifier of the bus master at the time of arbitration. The common information includes the information on the status of the common bus and the wait time, and transmits the information. As a result, the bus controller can support both a bus master that can receive only the bus use permission signal from the bus controller and a bus master that can receive the bus use permission signal and the common information from the bus controller.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A bus control system according to the present invention will be described below with reference to the drawings.

[First Embodiment] FIG. 1 is a schematic configuration diagram of a bus control system according to a first embodiment. However, the same components as in the conventional example (see FIGS. 6 and 8) are denoted by the same reference numerals, and detailed description thereof will be omitted.

The bus control system according to this embodiment is similar to the bus control system shown in FIG.
As shown in FIG. 1A, a common bus 1, a slave device (not shown) connected to the common bus 1, and a plurality of bus masters 10-1 to 10 for transferring data between the devices.
-n and a bus controller 20 for arbitrating the use request of the common bus 1 from each of the bus masters 10-1 to 10-n. The bus masters 10-1 to 10-n and the bus controller 20 are each connected to the common bus 1.

In such a bus control system, the bus masters 10-1 to 10-n and the bus controller 20 are respectively connected to the bus use request signal lines 51-1 to 51-n and one common signal line 50a. Connected by

The common signal line 50a is connected to each of the bus masters 10-1 to 10-1.
Information ACKINFO including a bus use permission signal, which is a result of arbitration for the bus use request signals REQ1 to REQn from 10-n, is used to commonly transmit to each of the bus masters 10-1 to 10-n. . However, the common signal line 50a is connected to all the bus masters 10-1 to 10-n. Therefore, information (hereinafter, referred to as common information) ACKINFO transmitted to each of the bus masters 10-1 to 10-n via the common signal line 50a indicates which bus master 10- It must be possible to distinguish between 1 and 10-n.

Therefore, when transmitting the common information ACKINFO, the bus controller 20 transmits the common information ACKINFO.
In addition to the bus use permission signal, the common information ACKINFO including identifier data for identifying the bus masters 10-1 to 10-n permitted to use the common bus 1 is transmitted via the common signal line 50a by a serial signal. Each bus master 10-1 ~ 10-n
To be sent to.

If the identifier data included in the common information ACKINFO requires high-speed processing in the system,
It should be transmitted first among the common information ACKINFO. Therefore, in the bus controller 20, for example, FIG.
Common information ACKINFO in the format as shown in (b)
To each of the bus masters 10-1 to 10-n.

That is, the common information ACKINFO is an identifier for identifying a bus master permitted to use the common bus 1 after an area (area (x) in the figure) which makes a state transition indicating the start of information. Area indicating data ((y) in the figure)
), Followed by an area (an area (z) in the figure) indicating other bus information whose details will be described later.

As the identifier data included in the common information ACKINFO, it is conceivable to use a bus master number previously assigned individually to each of the bus masters 10-1 to 10-n. Further, in addition to the bus master number, information relating to the priority assigned in advance to each of the bus masters 10-1 to 10-n may be used. The information on the priority order is not necessarily individually assigned to each of the bus masters 10-1 to 10-n, but may be information on grouping or the like. That is, the identifier data may be any data that can identify each of the bus masters 10-1 to 10-n.

For example, if the common information REQ1ACK is obtained when the use permission of the common bus 1 is given to the bus master 10-1,
Since it includes the identifier data of the bus master 10-1, it is configured as "0001XXXXX". Also,
Similarly, the common information REQ2 about the bus master 10-2
If it is ACK, it becomes "0010XXXXX". Further, if it is the common information REQnACK about the bus master 10-n (however, when n = 7), it becomes “0111XXXXX”. That is, these common information REQ1ACK to REQnACK include each bus master 10-1.
Identifier data of ~ 10-n is encoded.

The portion "XXXXX" of the common information REQ1ACK to REQnACK corresponds to other bus information. Other bus information includes information on the status of the common bus 1, the wait time, and the like. Specifically, for example, there is information for indicating to the other bus masters the period required for data transfer by the bus master permitted to use the common bus 1. Alternatively, the information may indicate a waiting period until the bus controller 20 transmits the next common information ACKINFO after the data transfer by a certain bus master is completed.

In the above-described format of the common signal, the case where the identifier data is 3 bits is illustrated, but this is determined according to the number of the bus masters 10-1 to 10-n. It is not limited to bits.

Next, an example of the operation of the bus control system configured as described above will be described with reference to the flowchart of FIG. 2 and the timing chart of FIG.

As shown in FIG. 2, in this bus control system, each of the bus masters 10-1 to 10-n gives the bus controller 20 the priority of its own device when trying to use the common bus. Bus use request signal RE containing information
Q1 to REQn are transmitted (Step 101, hereinafter, step is abbreviated as S). However, this does not apply when the priority of each of the bus masters 10-1 to 10-n is determined by the connection ports of the bus use request signal lines 51-1 to 51-n.

When the bus use request signals REQ1 to REQn are received from the bus masters 10-1 to 10-n (S102), the bus controller 20 checks whether the common bus 1 is already used by another bus master at that time. It is determined whether or not it is in use (S103). If the common bus 1 is not in use, the bus controller 20 subsequently determines whether or not the plurality of bus use request signals REQ1 to REQn are in conflict (S104). The arbitration for these bus use request signals REQ1 to REQn is performed based on the priorities of the signals REQ1 to REQn (S105).

Thus, each of the bus masters 10-1 to 10-n
When the use of the common bus 1 is permitted to any one of the bus masters, the bus controller 20 sets the common information ACKINFO including the identifier data of the bus master permitted to use the common bus 1.
Is transmitted to each of the bus masters 10-1 to 10-n (S106).

Specifically, as shown in FIG. 3, when the common bus 1 is not used (period (a) in FIG. 3), a bus master 10-1 transmits a bus use request signal REQ1. When the bus controller 20 comes, the common signal line 50a
The common information REQ1ACK is transmitted to each of the bus masters 10-1 to 10-n via the. Further, in a situation where a certain bus master 10-2 is using the common bus (period (b) in the figure), when a bus use request signal REQ1 is transmitted from another bus master 10-1,
The bus controller 20 transmits the common information REQ2ACK,
Then, the common information REQ1ACK is transmitted. Also, bus use request signals REQ1 to REQn from a plurality of bus masters 10-1 to 10-n.
Are conflicting (period (c) in the figure), the bus controller 20 transmits the common information REQ1ACK, the common information REQ2ACK, and the common information REQnACK in order.

On the other hand, in each of the bus masters 10-1 to 10-n, FIG.
As shown in FIG.
When KINFO is received (S107), the common information ACKINF
The identifier data of the bus master contained in O is decoded (S108), and it is determined whether or not the use permission of the common bus 1 from the bus controller 20 is for the own device (S109).

If the use permission of the common bus 1 is for its own device, the bus masters 10-1 to 10 that have received the use permission
-n starts data transfer using the common bus 1 (S11
0), after the data transfer is completed (S111), the bus use request signals REQ1 to RE
The transmission of Qn is stopped (S112). However, although not shown, transmission of the bus use request signals REQ1 to REQn to the bus controller 20 may be stopped after confirming that the use permission has been received for the last data transfer.

If the use of the common bus 1 is not permitted to the own device, the bus masters 10-1 to 10-n, that is, the bus masters 10-1 to 10 to which the use of the common bus 1 is not permitted.
In the case of -n, it is determined whether or not the urgency of the bus use request has changed according to the operation status inside and outside the bus master (S113). If there is no change, the bus use request signals REQ1 to REQn are transmitted to the bus controller 20. Continue (S101).

However, when the urgency of the bus use request changes, the bus masters 10-1 to 10-n, for example, take priority over the priority of the bus master specified by the identifier data included in the received common information ACKINFO. Also, the bus use request signal having the higher priority is retransmitted (S114) to ensure that the use of the common bus 1 is permitted in the next bus arbitration. In addition, since the well-known technique can be used for the change of the priority order, a detailed description is omitted here.

As described above, in the bus control system of this embodiment, the bus controller 20 transmits the common information ACKINFO including the bus use permission signal and the identifier data to each bus master 10 using one common signal line 50a. -1 to 10-n, and each bus master 10-1 to 10-n
Based on the identifier included in ACKINFO, it is recognized which bus master has been given permission to use the common bus 1.

Therefore, in this bus control system,
Since the common signal line 50a for transmitting the common information ACKINFO from the bus controller 20 connected to the common bus 1 to the plurality of bus masters 10-1 to 10-n is shared, the bus controller 20 changes the bus use permission signal line. Can be reduced,
In addition, since there is enough time for wiring signal lines, it is possible to connect to more bus masters and
By transmitting ACKINFO to the bus master, the bus master can determine the bus usage status and perform more efficient data transfer under the management of the bus master.

That is, in this bus control system, the transmission of the common information ACKINFO between the bus controller 20 and each of the bus masters 10-1 to 10-n is performed by the common signal line 50a, so that the wiring configuration therebetween is established. In addition to preventing the processing from becoming complicated, the processing in the bus controller 20 is not complicated, and as a result, the processing efficiency in the system can be improved.

In the bus control system according to the present embodiment, the bus controller 20 transmits the common information ACKINFO using a serial signal, so that the transmission of the common information ACKINFO is performed by one common signal line. 50a. Therefore, the influence on the increase in the number of input / output ports of the bus controller 20 is small, and the influence on the wiring is small, so that the system can be easily constructed.

In the bus control system of the present embodiment, the identifier data included in the common information ACKINFO transmitted to the bus master permitted to use the common bus 1 includes
By using a bus master number assigned in advance to each of the bus masters 10-1 to 10-n, the bus masters 10-1 to 10-n can use the predetermined processing without changing them. Become.

In the bus control system according to the present embodiment, the identifier data included in the common information ACKINFO transmitted to the bus master permitted to use the common bus 1 includes
If the use priority of the common bus 1 assigned in advance among the bus masters 10-1 to 10-n is used, the common bus 1
The priority of the bus master that is using
For example, when the urgency of data transfer increases due to a situation change such as the capacity of the built-in memory has been squeezed, a bus use request signal of a priority that can be given a bus use permission at the next bus arbitration can be issued without fail. The common bus 1 can be used efficiently, and the entire system can be operated reliably.

In the bus control system of the present embodiment, if the common information ACKINFO includes information indicating a period required for data transfer by the bus master permitted to use the common bus 1, the common information ACKINFO is received. The bus master can check the period until the currently operating data transfer is completed, and this can be incorporated into the determination of the usage status of the common bus 1.

In the bus control system of the present embodiment, the common information ACKINFO includes information indicating a waiting period from the end of data transfer by the bus master permitted to use the common bus 1 to the next common information. If common information
It is possible for the bus master receiving ACKINFO to incorporate the period from the end of the currently operating data transfer to the reception of the next common information in the determination of the usage status of the common bus 1.

Further, in the bus control system according to the present embodiment, after issuing a request to use the common bus 1 to the bus controller 20, before the bus controller 20 obtains permission to use the common bus 1, another bus master may be used. Is common bus 1
When the bus master recognizes that use of the common bus is permitted, the bus master generates a new common bus use request based on the common information ACKINFO, and transmits the request to the bus controller 20 again. That is, the bus master that has requested the use of the common bus 1 but has been rejected can transmit a new bus use request signal based on the decoding result of the received common information ACKINFO. Thereafter, the data transfer can be reliably performed.

[Second Embodiment] Next, a second embodiment of the bus control system according to the present invention will be described. However, here, only the differences from the above-described first embodiment will be described.

The bus control system according to this embodiment is similar to the bus control system shown in FIG.
As shown in the figure, a bus use request signal line 51 for transmitting bus use request signals REQ1 to REQn from the bus masters 11-1 to 11-n is provided between the bus masters 11-1 to 11-n and the bus controller 21.
-1 to 51-n and bus use permission signal lines 52-1 to 52 for transmitting bus use permission signals ACK1 to ACKn from the bus controller 21.
-n and common information ACKINF for each bus master 11-1 to 11-n
It is connected by one common signal line 50b for transmitting O 2.

In the bus control system configured as described above, as shown in FIG. 5, when the common bus 1 is not used, a bus master 11-1 sends a bus use request signal REQ1.
Is transmitted (period (d) in the figure), the bus controller 21 transmits the bus use permission signal ACK1 to only the bus master 11-1 via the bus use permission signal line 52-1. Common signal line 50 for each bus master 11-1 to 11-n
b transmits the common information ACKINFO via the common bus 1
Hold its state until it becomes available.

Also, when a bus use request signal REQ1 is transmitted from another bus master 11-1 in a situation where a certain bus master 11-2 uses the common bus 1 (period (e) in the figure). After waiting until the common bus 1 becomes available, the bus controller 21 sends the bus use permission signal AC to the other bus master 11-1 via the bus use permission signal line 52-1.
While transmitting K1, the common information ACKINFO is transmitted to each of the bus masters 11-1 to 11-n via the common signal line 50b.

When the bus use request signals REQ1 to REQn from the plurality of bus masters 11-1 to 11-n conflict (period (f) in the figure), the bus controller 21 has the highest priority at that time. The bus use permission signals ACK1 to ACKn are transmitted to the bus masters 11-1 to 11-n of the order, and the common information ACKINFO is transmitted to the bus masters 11-1 to 11-n via the common signal line 50b.

As described above, the bus use permission signal line 52 is provided between each of the bus masters 11-1 to 11-n and the bus controller 21.
Since -1 exists separately from the common signal line 50b, the common information
ACKINFO need not include the identifier data of the bus master permitted to use the common bus 1. However, if identifier data is included in the common information ACKINFO, there are bus masters that recognize the identifier data and perform subsequent processing (for example, changing priority or error processing) and bus masters that do not. , It is possible to cope with both of them.

That is, in this bus control system, the bus use permission signal line 52 as in this embodiment is provided in the system.
-1 to 52-n and a bus master connected to the common signal line 50b,
A bus master connected only to the common signal line 50b as in the first embodiment, or a bus master connected only to the bus use permission signal lines 52-1 to 52-n as in the related art may coexist. Therefore, in this bus control system, even if it is necessary to add a new bus master in the system, the versatility and expandability of the system are ensured, so that this can be easily coped with.

As described above, in the bus control system according to the present embodiment, in addition to the bus use permission signal line 52-1, the common information
By adding the common signal line 50b for transmitting ACKINFO, the common information ACKINFO is transmitted to the bus master with little influence on the number of input / outputs of the bus controller 21 and the increase in the number of wiring signal lines. And more efficient data transfer is possible under the control of the bus master, and the bus use permission signal lines 52-1 to 52
By separating -n and the common signal line 50b, conventionally used bus masters can be mixed and used, so that a flexible system construction can be realized.

That is, in this bus control system, the first
In addition to the effects described in the first embodiment, it is possible to obtain an effect that versatility and expandability of the system can be ensured.

In the bus control system of the present embodiment, the bus use permission signal lines 52-1 to 52-n and the common signal line 50b
Since the bus controller 21 transmits the common information ACKINFO including the identifier data of the bus master that has permitted the use of the common bus 1, the use of the common bus 1 is not permitted. Bus master can more reliably determine the usage status of the common bus 1.

In the first and second embodiments described above, when the bus master whose urgency of the bus use request has changed retransmits a new bus use request signal, the common information ACKI is used.
Although the case where the priority of each bus master is determined from the identifier data and the like included in the NFO has been described as an example, the following may be considered in addition to this. For example,
The time required for the bus master to use the common bus 1 for data transfer, and the new common information ACKINF including the next bus use permission signal or the bus use permission signal after the data transfer is completed.
The waiting period until O is included in the common information ACKINFO based on the time, the number of clocks, the number of data transfers, or information obtained by encoding these data, and the like.
The bus master, based on the status change of the bus master whose use of the bus is not permitted and the period until the next bus use is permitted,
A bus use request signal having a higher priority than the priority of the bus master using the common bus 1 included in the common information ACKINFO may be transmitted.

Further, in the first and second embodiments, information relating to the status and wait time of the common bus 1 has been exemplified as the other bus information included in the common information ACKINFO. , Information about the common bus 1 such as slave device identifier information at the time of data transfer, transfer rate information at the time of data transfer, data transfer amount information at the time of data transfer, and the like. Good.

[0063]

As described above, the bus control system of the present invention uses a common signal line for transmitting common information from a bus controller connected to a common bus to a plurality of bus masters. Can reduce the number of bus use permission signal lines, and allow time for wiring signal lines, so that it can be connected to more bus masters, and by transmitting common information to the bus masters, To determine the bus use status, and more efficient data transfer becomes possible under the control of the bus master.

In addition, the bus control system of the present invention adds a common signal line for transmitting common information in addition to the bus use permission signal line, thereby giving an increase in the number of inputs / outputs of the bus controller and an increase in the number of wiring signal lines. By transmitting common information to the bus master with little effect, the bus master can determine the bus usage status, enabling more efficient data transfer under the control of the bus master.In addition, the bus use permission signal line and common signal line By separating the bus masters, the bus masters conventionally used can be used together, so that a flexible system construction can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of a bus control system according to the present invention, wherein FIG. 1 (a) is a diagram showing the overall configuration, and FIG. 1 (b) is a diagram showing a format of common information.

FIG. 2 is a flowchart illustrating an example of a processing operation according to the first embodiment.

FIG. 3 is a timing chart showing a specific example of a processing operation example according to the first embodiment.

FIG. 4 is a schematic configuration diagram of a second embodiment of the bus control system according to the present invention.

FIG. 5 is a timing chart showing a specific example of a processing operation example according to the second embodiment.

FIG. 6 is a schematic configuration diagram (part 1) illustrating an example of a conventional bus control system.

FIG. 7 is a timing chart showing a specific example of a processing operation example in a conventional bus control system.

FIG. 8 is a schematic configuration diagram (part 2) illustrating an example of a conventional bus control system.

[Explanation of symbols]

1: common bus, 10-1 to 10-n, 11-1 to 11-n: bus master,
20, 21: bus controller, 50a, 50b: common signal line, 52-1 to 52-n: bus use permission signal line, ACKINFO ...
Common information

Continued on the front page (72) Inventor Takashi Ohara 2274 Hongo, Ebina-shi, Kanagawa Fuji Xerox Co., Ltd.

Claims (9)

[Claims] 1. A bus control system comprising: a common bus; a plurality of bus masters for performing data transfer using the common bus; and a bus controller for arbitrating a common bus use request from the plurality of bus masters. The bus controller uses a single signal line commonly connected to the plurality of bus masters to transmit common information including a bus use permission signal to the bus master that has permitted use of the common bus by the arbitration and an identifier of the bus master. And a common information transmitting means for transmitting to each of the plurality of bus masters, wherein each of the plurality of bus masters, when the common information is transmitted from the common information transmitting means, an identifier of a bus master included in the common information Permission of use of the common bus to any one of the plurality of bus masters based on the Bus control system, characterized in that it comprises an authorization recognition means for recognizing whether a given. 2. A bus control system comprising a common bus, a plurality of bus masters performing data transfer using the common bus, and a bus controller arbitrating a common bus use request from the plurality of bus masters. The bus controller, a use permission transmitting unit that transmits a bus use permission signal only to the bus master that has permitted the use of the common bus by the arbitration, apart from the bus use permission signal, the bus controller is commonly connected to the plurality of bus masters; And a common information transmitting means for transmitting common information to each of the plurality of bus masters using one signal line. 3. The bus according to claim 2, wherein the common information transmitting means transmits the common information including an identifier of a bus master whose use of the common bus is permitted by the arbitration. Control system. 4. The bus control system according to claim 1, wherein said common information transmitting means uses a serial signal for transmitting said common information. 5. The bus control system according to claim 1, wherein the bus master identifier included in the common information uses a bus master number assigned to each of the plurality of bus masters in advance. 6. The bus master identifier included in the common information uses a priority order of use of the common bus, which is allocated in advance among the plurality of bus masters. Bus control system. 7. The common information transmitting means, wherein the common information includes information indicating a period required for data transfer by a bus master permitted to use the common bus, and transmitting the information. Item 1, 2, 3, 4, 5, or 6
A bus control system as described. 8. A waiting period from the end of data transfer by the bus master permitted to use the common bus to the next bus use permission signal or new common information including the bus use permission signal, wherein the common information transmission means is provided. 7. The bus control system according to claim 1, wherein the information indicating the transmission is included in the common information and transmitted. 8. 9. The bus master, after issuing a request to use the common bus to the bus controller, before obtaining a permission to use the common bus by the bus controller, the other of the plurality of bus masters. When the bus master recognizes that the use of the common bus is permitted, the bus master generates a new common bus use request based on the common information and transmits the request to the bus controller. Claims 1, 2, 3,
The bus control system according to 4, 5, 6, 7, or 8.