KR20060000257A - Bus-system for adjusting the priority order of masters and method thereof - Google Patents

Abstract

A bus system and a method of operating the same are disclosed. The bus system includes at least one master requesting the use of a bus, a bus bridge connecting at least two bus systems, a bus mediator for allocating the use of the bus upon requesting the use of the bus from at least one master and the bus bridge, and If priority is set to the bus use assignment of the bus bridge, a bus masking unit for masking the bus use request of the master is provided. Accordingly, in an extended bus system in which a plurality of single layer bus systems are connected by using a bus bridge, a master or slave receiving data is transmitted in accordance with the priority of masters on the bus system side having a master for transmitting data. Priority control of the masters on the bus system side enables the bus to be used more efficiently.

Bus system, master, slave, priority

Description

Bus system for adjusting the priority of masters and its operation method

1 is a block diagram showing a conventional extended bus system,

2 is a block diagram illustrating an extended bus system according to an embodiment of the present invention;

3 is a circuit diagram illustrating in detail a bus masking unit applied to the bus system shown in FIG. 2;

4 is a timing diagram showing an operation timing of the bus system of FIG.

5 is a flowchart provided to explain a method of operating a bus system according to an exemplary embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10: Bus Arbiter 1 20: Bus Bridge

30: bus masking unit 40: bus intermediary 2

The present invention relates to a bus system and a method of operating the same, and more particularly, to a bus system in which a master transmits data to a master or slave in an extended bus system in which a plurality of bus systems are connected, and a method of operating the same.

BusSystems generally have a number of Masters and Slaves and a BusArbiter on a single layer bus. In other words, when the bus intermediary authorizes the use of the bus according to the master's request to use the bus, the masters use the bus to transfer data to the master or slave.

The master has bus access to the bus system and is connected in parallel to one common bus. The master uses the bus to access data to other masters and slaves. The master can also use the bus to request data from other masters and slaves. Examples of masters include Ethernet and central processing unit (CPU).

When a bus intermediator sends a signal requesting the use of a bus, it assigns the use of the bus by receiving a signal and setting priorities for each master so that the master can use the bus.

Specifically, the bus arbitrator sees how often the bus has been used for each master and prioritizes the use of the bus. Alternatively, priority is given to the use of the bus according to the control program of the bus intermediator.

Priority setting is generally set when the bus system is powered up because it is overloaded when the master in the bus system transmits data each time.                         

In the above, the components provided in the general single layer bus system have been described. Hereinafter, a bus system (two layer bus system) having at least two single layer buses is referred to as an extended bus system. Referring to Fig. 1, the extended bus system will be described in detail.

1 is a block diagram showing the configuration of a conventional extended bus system.

Referring to FIG. 1, FIG. 1 is a two-layer bus system in which a first bus system 1 and a second bus system 5 are connected by a bus bridge 20. have.

The bus bridge 20 transfers data from a master provided in the first bus system to a master or slave provided in the second bus system, and vice versa, from a master provided in the second bus system to a master or slave provided in the first bus system. It serves as an interface.

The extended bus system interconnects the first bus system 1 and the second bus system 5 using the bus bridge 20. That is, the master existing in the first bus system 1 transmits or receives data to the master or slave existing in the second bus system 5 using the bus bridge 20.

In addition, it is possible for the master existing in the second bus system 5 to transmit or receive data to the master or slave existing in the first bus system 1 using the bus bridge 20.

The first bus system 1 has a master A, a master B, a master C, and a bus intermediary 1 10. The second bus system 5 has a master D, a master E, a master F, a slave and a bus intermediary 2 (40). The first bus system 1 and the second bus system 5 are connected by a bus bridge 20.

Hereinafter, a case in which the master configuring the first bus system requests the use of the bus of the second bus system will be described.

In the conventional bus system, when the masters A, B, and C provided in the first bus system 1 request the bus intermediator 1 10 to use the bus, the bus intermediary 1 10 receives the request signal and is described above. In one way, each master is given priority to use the bus.

As an example, it is assumed that bus arbitrator 1 (10) gives priority to masters A, B, and C in order. Accordingly, the master A having the first priority requests the bus bridge 20 to use the bus of the second bus system using the bus of the first bus system to request the use of the bus of the second bus system. . Then, at the request of the master A, the bus bridge 20 requests the bus intermediary 2 40 provided in the second bus system 5 to use the bus. At the same time, the masters D, E, and F provided in the second bus system 5 also request the use of the bus.

Then, the bus intermediator 2 40 receives the request signals from the bus bridge 20, the masters D, E, and F, and gives priority to the components that sent the request signals in the same manner as the bus intermediary 1. .

However, this conventional technique, when viewed from the second bus system side, the bus intermediator 2 receives priority request signals of the bus bridges, masters D, E, and F, and gives priority to the first bus system. The provided masters appear to have the same priority as the priority of the bus bridges given in the second bus system.

Therefore, when the bus bridge is given a low priority in the second bus system, even if a master provided in the first bus system having a high priority needs to transmit data quickly, the bus bridge may be ordered according to the low priority of the bus bridge. You have to wait and send data.

On the other hand, if the bus bridge is given a high priority, the master provided in the first bus system having the low priority may transmit data according to the high priority of the bus bridge even though the master may transmit data slowly. In addition to lowering the efficiency of use, it can provide a cause of overload.

Accordingly, an object of the present invention is to provide a bus system capable of adjusting the priority of masters and an operating method thereof in an extended bus system in which a plurality of single layer bus systems are connected by using a bus bridge.

A bus system according to the present invention for achieving the above object comprises at least one master requesting the use of a bus, a bus bridge connecting at least two bus systems, the use of a bus from the at least one master and the bus bridge. And a bus masking unit for allocating a bus use request and a bus masking unit for masking a bus use request of the master if a priority is set in the bus use allocation of the bus bridge.

The bus masking unit may prevent the master from transmitting a signal requesting the use of a bus to the bus intermediator.

On the other hand, the operation method of the bus system of the present invention, in a bus system consisting of a bus intermediator, at least one master and slave, connected to at least two or more using a bus bridge, the method of allocating the use of the requested bus,

Receiving a request for use of a bus from the bus bridge and the master; masking a bus use request of the master; Assigning.

The bus masking unit may prevent the master from transmitting a signal requesting the use of a bus to the bus intermediator.

Hereinafter, with reference to the drawings will be described the present invention in more detail.

2 is a block diagram illustrating an extended bus system according to an embodiment of the present invention.

Referring to FIG. 2, the bus system is a two-layer bus system structure in which two independent single layer bus systems are connected through a bus bridge 20. The bus intermediate apparatuses 1, 2 (10, 40), and bus bridges 20, and a bus masking unit 30.

In Fig. 2, with the bus bridge 20 in between, the first bus system includes Master A, Master B, Master C, and Bus Intermediate 1 (10), and the second bus system includes Master D and Master E. And a master F, a bus masking unit 30, and a bus intermediator 2 (40).

Obviously, the first bus system and the second bus system may include other components in addition to the above-described components. In particular, the first bus system also includes a bus masking unit 30 but is omitted for convenience of description.

2 shows the input and output signals of the bus intermediate apparatuses 1, 2 (10, 40), the bus bridge 20, and the bus masking section 30. As shown in FIG.

The bus masking unit 30 may use buses of other masters except for bus use requests of masters having a high priority based on the priority of all masters connected to the bus system in an extended bus system in which a plurality of single layer bus systems are connected. Mask the request.

Specifically, masters A, B, and C request bus intermediary 1 (10) to use the buses of the first bus system and the second bus system. As an example, it is assumed that bus intermediate apparatus 1 (10) grants a first priority to master C to permit the use of a bus. When the master C accesses data to the bus bridge 20 in order to access the data to the master or slave provided in the second bus system, the bus bridge 20 is connected to the bus intermediate apparatus 2 40 of the second bus system. Ask to use the bus.

In addition, the bus bridge 20 transmits a mask enable signal to the bus masking unit 30. At the same time, the masters D, E, and F provided in the second bus system also transmit a signal requesting the use of the bus to the bus masking unit 30.                     

Detailed operations of the bus masking unit will be described with reference to FIG. 3.

3 is a circuit diagram illustrating in detail a bus masking unit applied to the bus system apparatus of FIG. 2.

Referring to FIG. 3, the bus masking unit 30 includes an AND gate. The bus request-bridge signal is used by the bus bridge 20 to request bus intermediary 2 40 to use the bus in order to transmit data received from the master C having the first priority in the first bus system to the second bus system. It is a signal.

The mask enable signal is a signal for masking bus use request signals of the masters provided in the second bus system when the master C has a higher priority than the masters constituting the second bus system.

Specifically, the mask enable signal has "0" and "1". The mask enable signal has a "1" when the busbridge requests a high priority for bus usage, and has a "0" when requesting a low priority.

Also, it is assumed that the master transmits "1" as the bus request signal when the master requests the use of the bus and transmits "0" as the bus request signal when the master does not request the use of the bus.

When the mask enable signal is "1", the AND gate provided in the bus masking unit 30 outputs "0" regardless of the bus request signals of the masters. That is, when the mask enable signal is "1", the bus masking unit 30 blocks the bus request signals transmitted by the masters D, E, and F provided in the second bus system to "0". Therefore, bus intermediate device 2 40 receives only the bus request-bridge signal.                     

If the mast enable signal is "0", the AND gate outputs the bus request signals of the masters. That is, when the mask enable signal is "0", the bus masking unit 30 outputs the same signal as the bus request signal transmitted by the masters D, E, and F provided in the second bus system, thereby providing bus intermediary 2 (40). ) Receives the bus request-bridge signal and the bus request signals transmitted by D, E, and F.

Although FIG. 2 illustrates the bus masking unit 30 and the bus intermediator 2 40 in separate configurations, it is obvious that the bus masking unit 30 and the bus intermediator 2 40 may be designed in one configuration according to the user's setting. 40 may perform the function of the bus masking unit 30.

A specific example will be described below with reference to FIG. 4.

4 is a timing diagram illustrating an operation timing of the bus system of FIG. 2.

Referring to FIG. 4, masters A, B, and C transmit bus requests-A, B, and C signals a, b, and c to bus intermediary 1 (10) requesting the use of a bus.

Bus intermediary 1 (10) receives the bus request-A, B, C signals (a, b, c) to give a priority to the master C first priority to transmit the bus permission signal (d). The master C, which is permitted to use the bus, uses the bus to access data to the bus bridge 20.

The bus bridge 20 receiving the data of the master C transmits a signal for requesting the use of the bus and a mask enable signal e to the bus masking unit 30 and the bus intermediator 2 40.

The masters D, E, F also transmit bus requests-D, E, F signals (f, g, h) to the bus masking unit (30).

As described with reference to FIG. 3, the bus masking unit 30 outputs a mask enable signal from the bus bridge 20 as "1", and the masters D, E, and F are bus request signals f, g, and h. Mask out from exporting.

Therefore, since only the signal e for which the bus bridge 20 requests the use of the bus is transmitted to the bus intermediate device 2 40, the bus bridge 20 receives the signal i for which the use of the bus is permitted.

5 is a flowchart provided to explain a method of operating a bus system according to an exemplary embodiment of the present invention.

Referring to FIG. 5, when power is applied to an extended bus system consisting of a first bus system and a second bus system, each master provided in the first bus system requests the bus intermediator 1 (10) to use the bus. The signal is transmitted (S500).

The bus intermediary 1 (10) receives a request to use the bus, sets the priority of allowing the use of the bus by looking at how often each master used the bus. Or, according to the control program is set the priority to allow the use of the bus (S510).

The master, which has received the first priority, determines whether to transmit data to the master or slave included in the second bus system or the data based on the address of the data (S520). ).

If the address is a master or slave included in the first bus system, the master having the first priority accesses data using the bus authorized as the master or slave corresponding to the address (S530). It exits after the data is accessed.

If the address is a master or slave included in the second bus system, the master having the first priority accesses data to the bus bridge 20 (S540).

The bus bridge 20 receiving the data transmits a mask enable signal to the bus masking unit 30 in order to use the bus of the second bus system, and sends a signal requesting bus use to the bus intermediary 2 40. send. Masters provided in the second bus system also transmit a signal requesting the use of the bus to the bus masking unit 30 (S550).

The bus masking unit 30 determines whether the mask enable signal received from the bus bridge 20 is "0" or "1" (S560). If the mask enable signal is "0", the bus bridge requests a low priority for bus usage. If the mask enable signal is "1", the bus bridge requests a high priority for bus usage.

When the mask enable signal is "0", the bus bridge 20 receiving data from the master provided in the first bus system and the masters provided in the second bus system use the bus to the bus intermediate apparatus 2 40. Transmit the signal requesting (S570).

Bus intermediary 2 (40) resets the priority to each master provided in the bus bridge 20 and the second bus system (S580). Based on the set priority, the bus bridge 20 having the first priority or the master provided in the second bus system accesses data to the master or slave provided in the second bus system (S590). After the data has been transmitted, it is terminated.

As a result of the determination in step S560, when the mask enable signal is “1”, the bus masking unit 30 masks the bus request signal so that masters provided in the second bus system do not request the use of the bus (S600).                     

Since all the bus request signals of the other masters are masked, the bus bridge 20 uses the bus to transfer data received from the master provided in the first bus system to the master or slave provided in the second bus system corresponding to the address. To access (S610). After the data has been transmitted, the operation is terminated.

Of course, if the master provided in the second bus system intends to transmit data to the first bus system, it is possible to perform the same process as described above.

As described above, according to the present invention, in an extended bus system composed of a plurality of single layer bus systems, a master or slave receiving data is transmitted in accordance with the priority of the masters on the bus system side having a master for transmitting data. Priority control of the masters on the side of the bus system is provided, which increases the efficiency of use of the bus.

In addition, although the preferred embodiment of the present invention has been shown and described above, the present invention is not limited to the specific embodiments described above, but the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be understood from the technical spirit or the prospect of the present invention.

Claims (4)

At least one master requesting the use of a bus; A bus bridge connecting at least two bus systems; A bus mediator for allocating the use of the bus upon receiving the use of the bus from at least one of the master and the bus bridge; and And a bus masking unit for masking a bus use request of the master, if a priority is set in the bus use allocation of the bus bridge. The method of claim 1, The bus masking unit, And prevent the master from transmitting a signal requesting the use of a bus to the bus intermediary. In a bus system composed of a bus intermediator, at least one master and a slave and connected to at least two or more bus systems using a bus bridge, Receiving a request for use of a bus from the bus bridge and the master; Masking a bus use request of the master, if a priority is set to the bus use assignment of the bus bridge; and Allocating the bus usage requested by the bus bridge. The method of claim 3, wherein The masking step, And preventing the master from transmitting a signal requesting the use of a bus to the bus intermediary.

Images