JPH0314059A - Bus system - Google Patents

Abstract

PURPOSE:To efficiently change the system configuration of a bus system even in the middle of operation by providing each bus device with an ID number table, where a physical ID number is set correspondingly to the logical ID number peculiar to the bus device, and a means which changes the physical ID number. CONSTITUTION:In the bus system where plural bus devices 20 to 27 are connected to a bus 10 and the use priority of the bus 10 is determined based on assigned physical ID numbers, each of bus devices 20 to 27 is provided with an ID number table 42 where the logical ID number peculiar to the bus device and the physical ID number corresponding to the logical ID number are set and a changing means 41 which changes the physical ID number based on the ID number change request. When the bus use request having a high priority level occurs in the bus device of low bus use priority, the bus device is enabled to easily get the use right of the bus; and thus, the bus system configuration is changed on demand.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bus system and a method for changing bus usage priority to 2%.

[Prior Art] Conventionally, as a bus system, for example, SC8I (Sm
All Computer System Inter
A known method is to give an ID number to a bus device and set (fix) priority rights to use the bus based on this ID number, as used in the Internet.

Further, as a bus system, a bus system including a plurality of bus devices and a bus arbitration means is known. Usage priority is fixed.

[Problem to be solved by the invention] By the way, in the case of the conventional bus system mentioned above.

The priority right to use the bus is fixed by an ID number that is logically and physically predetermined for each bus device, or the priority right to use the bus is determined by physically connecting each bus device and bus arbitration means. Fixed. In any case, in conventional bus systems, the bus usage priority is fixed.1 For example, when a bus usage request with a high priority occurs to a bus device with a low bus usage priority, the bus usage right is granted. The problem is that it is extremely difficult to obtain.

An object of the present invention is to provide a bus system that allows bus usage rights to be obtained as needed.

[Means for Solving the Problems] According to the present invention, there is provided a bus in which a plurality of bus devices are connected to a bus, and the priority of use of the bus is determined based on the physical ID number assigned to the bus device. In the system,
The bus device includes an ID number table in which a logical ID number unique to each bus device and the physical ID number are set corresponding to the logical ID number, and the physical ID number is changed based on an ID number change request. A bus system is obtained, characterized in that it is equipped with a changing means.

Furthermore, in the present invention, in a bus system in which bus use requests from a plurality of bus devices are arbitrated by a bus arbitration means, the bus arbitration means has a priority order that defines a priority order for each bus use right acquisition request of each bus device. The definition means compares bus use right acquisition requests from each bus device with the priority order.

bus arbitration means for granting bus use rights to each bus device;

A bus system is obtained, comprising a priority order changing means for changing the priority order in response to a priority order change request from each bus device.

In this case, the central processing unit detects the bus use right acquisition status of each bus device and issues a priority order change command based on the detection result, and the priority order change means changes the priority order according to the priority order change command. It may be changed.

Further, the priority order changing means may monitor the degree to which each of the bus devices has acquired the right to use the bus, and change the priority order based on the observation result.

[Example] Next, one embodiment of the present invention will be explained with reference to examples.

First, referring to FIG. 1, a plurality of bus devices 20-27 are connected to a bus 1o. As shown in FIG. 2, the bus device 2o has a logical ID setting unit 41° and a physical ID correspondence table 42. and a bus control section 43, and the other bus devices 21 to 27 are similarly configured.

When each of the bus devices 20 to 27 attempts to obtain the right to use the bus, it requests use of the bus by setting the bit corresponding to its own physical ID on the data line of the bus 10 to logic 1. At this time, if multiple bus devices request use of the bus, the ID
The priority is determined by the weight of the bus, and the right to use the bus is determined. The above logical ID is set by the logical ID setting section 41.

When the power is turned on, a table with the same logical ID and physical ID is created as the logical ID/physical ID correspondence table 42, as shown in FIG. At this point, logical ID=
The bus device with logical ID=0 has the highest priority, and the bus device with logical ID=O has the lowest priority.

Here, when the bus device with logical ID=5 tries to obtain the highest priority, the logical ID/physical ID correspondence table 42
Referring to , a message is sent to the bus device with logical I I)=7 to request an exchange of physical IDs. logic I
When the bus device with D=7 responds, the bus device with logical ID=5 notifies all bus devices of the physical ID exchange. In response to this notification, each bus device rewrites the logical ID/physical ID correspondence table 4'2 within its own bus device, as shown in phase 1 of FIG.

After the logical ID/physical ID correspondence table 42 is rewritten in this way (phase 1 state).

When a bus device with logical ID=5 makes a request to use the bus, it first reads its own ID "5" from the logical ID setting section 41. After that, the bus control section 43.

Refer to the logical ID/physical ID correspondence table 42.

Knowing that logical ID=5 corresponds to physical ID=7, bit 7 of the data line of bus 10 is set to logic 1 to request use of the bus. After getting the right to use the bus.

When attempting to connect to a bus device with logical ID=1, the bus control unit 43 refers to the logical ID/physical ID correspondence table 42, learns that logical ID=1 corresponds to physical ID=1, and connects to the bus device with logical ID=1. Bit 7 and bit 1 of data line 10 are set to logic 1, and a connection is requested to the bus device with logic ID=1.

Next, when the bus device with the logical ID=3 tries to obtain the highest priority, the logical ID/physical ID correspondence table 42 indicates that the bus device with the logical ID=5 corresponding to the physical ID=7 Similarly, a request is made to exchange physical IDs. If this is successful, the state of phase 2 in FIG. 3 is reached.

Next, a second embodiment of the present invention will be described.

Referring to FIG. 4, the bus 10 includes a plurality of bus devices 31 to 31.
3N and a bus arbitration unit 50 are connected, and the bus arbitration unit 5o arbitrates bus use requests from the bus devices 31 to 3N. As shown in FIG. 5, the bus arbitration unit 50 includes a bus use request arbitration circuit 51, a priority order definition table 52. A priority order changing section 53 is provided.

In FIG. 5, 61 to 6N are bus use right acquisition requests from each bus device 31 to 3N, 71 to 7N are bus use permissions to each bus device 31 to 3N, and these signals are A one-to-one connection is made between the devices 31 to 3N and the bus arbitration section 50.

When each of the bus devices 31 to 3N attempts to obtain the right to use a bus, it sends a request to obtain the right to use the bus to the bus arbitration unit 50. At this time, when bus use right acquisition requests are input to the bus arbitration unit 50 from a plurality of bus devices, the bus arbitration unit 50
0 refers to the value in the priority order definition table 52 and grants permission to use the bus to a bus device with a higher priority.

The right to use the bus is determined as described above.

Bus devices that are set to have a low priority in the initial settings of the system (for example, bus device 31 has the highest priority,
The priority order decreases in descending order of priority, with the bus device 2N being set the lowest.) It may be difficult to obtain the right to use the bus. To avoid such a situation, a bus device with a low priority requests the bus arbitration unit 50 to change its priority. The bus arbitration unit 50 accepts this request.

The priority order changing unit 53 changes the priority order definition table 52. When the priority order definition table 52 is changed in this way, the priority order of each bus device in arbitration of bus use requests from the second time onward is changed.

In the second embodiment, a case has been described in which the bus device requests the bus arbitration unit 50 to change the priority order, but in the third embodiment, as shown in FIG. If the configured bus device is unable to obtain the right to use the bus for a predetermined period of time, the central processing unit (not shown) detects this condition and gives a higher priority to the bus device with a lower priority. A priority order change request 81 is given to the bus arbitration unit 50. When this request is input to the bus arbitration section 50, the priority order change section 53 changes the priority order definition table 52. When the priority order definition table 52 is changed in this way, the priority order of each bus device in arbitration of bus use requests from the second time onward is changed.

In the fourth embodiment, as shown in FIG. 7, the priority change unit 53 sends bus use right acquisition requests from each bus device and bus use permission to each bus device to a bus use request arbitration circuit 51.
Priority definition table 5
Change 2. In this way, priority definition table 5
If 2 is changed, the priority order of each bus device in arbitration of bus use requests from the first time is changed.

There are no bus devices for which the right to use the bus is not granted for a long time in response to a request to acquire the right to use the bus.

[Effects of the Invention] As explained above, in the present invention, the logical ID number determined at the time of system setup is not changed.

Since the physical ID number that determines bus usage priority is dynamically changed, during the initial system settings,
For bus devices with low bus usage priority.

When a high-priority usage request occurs, the system configuration of the bus system can be efficiently changed even during operation, such as by increasing the usage priority of the bus device.

In addition, the priority order for acquiring the right to use the bus, which is defined based on physical elements at the time of system initialization, is dynamically changed when using the bus. When a high-priority usage request occurs, the system configuration of the bus system can be changed efficiently even during operation, such as by increasing the priority for acquiring the bus usage right for that bus device.

In any case, since the bus use right acquisition priority order is changed, there is an effect that it can be efficiently changed while the bus system l1fl is in operation.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the bus system according to the present invention, FIG. 2 is a block diagram showing the configuration of the Nonosu device shown in FIG. 1, and FIG. 3 is a block diagram showing the configuration of the Nonosu device shown in FIG. 4 is a block diagram showing another embodiment of the bus system according to the present invention, and FIG. 5 is a diagram showing the correspondence table shown in FIG. 4.
A block diagram showing an embodiment of the JS arbitration unit, FIG.
7 is a block diagram showing still another embodiment of the bus arbitration section shown in FIG. 4. FIG. 7 is a block diagram showing still another embodiment of the bus arbitration section shown in FIG. 10... Bus, 20-27... Bus device, 31-3
N... Bus device, 41... Logical ID setting section, 42.
...Logical ID/physical ID correspondence table, 43...NoZ
Bus control unit, 50 Bus control unit, 51 Bus use request arbitration circuit, 52 Priority definition table, 53
...Priority change section. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 0

Claims (1)

[Scope of Claims] 1. In a bus system in which a plurality of bus devices are connected to a bus, and priority for use of the bus is determined based on a physical ID number assigned to the bus device, each bus device has a An ID number table in which a logical ID number unique to the bus device and the physical ID number are set corresponding to the logical ID number, and a changing means for changing the physical ID number based on an ID number change request. The bus system is characterized by: 2. In a bus system in which bus use requests from a plurality of bus devices are arbitrated by a bus arbitration means, the bus arbitration means includes a priority definition means for defining priorities for bus use right acquisition requests of each bus device; a bus arbitration unit that compares a bus use right acquisition request from a bus device with the priority order and grants the bus use right to each bus device; and a priority order that changes the priority order according to a priority change request from each bus device. A bus system comprising: changing means. 3. In a bus system used in a system equipped with a central processing unit, in which bus use requests from a plurality of bus devices are arbitrated by a bus arbitration means, the bus arbitration means is configured to set a priority order for bus use right acquisition requests of each bus device. a priority definition means for defining a priority order; a bus arbitration means for comparing a bus use right acquisition request from each bus device with the priority order definition means and granting a bus use right to each bus device; and a bus arbitration means for changing the priority order. The central processing unit detects the bus use right acquisition status of each of the bus devices and issues a priority change command based on the detection result, and the priority change means detects the bus usage right acquisition state of each bus device and issues a priority change command based on the detection result. A bus system characterized in that the priority order is changed by a command. 4. In a bus system in which bus use requests from a plurality of bus devices are arbitrated by a bus arbitration means, a priority definition means for defining priorities for bus use right acquisition requests from each bus device, and a bus use right acquisition request from each bus device. A bus arbitration means that compares the acquisition request with the priority order definition means, observes the bus arbitration means that grants the bus use right to each bus device, and the degree of acquisition of the bus use right of each bus device, and determines the priority order based on the observation result. 1. A bus system comprising: priority order changing means for changing the order.