JP2006085537A - Bus arbitration system, bus arbitration device, and bridge device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bus arbitration system for acquiring a bus in the same waiting time even in accessing a bus slave through a plurality of buses as in accessing the bus slave through a single bus. <P>SOLUTION: A bus arbiter 8 for allocating a citizenship of the bus B2 to either of a plurality of bus masters 5, 6 connected to the bus B2 is provided with: an initial value setting part 82 for acquiring priority information from a priority of data transmission and a time required for acquiring the citizenship of the bus B1 on the data transmission; and a permitting means for selecting the one bus master out of the plurality of the bus masters 5, 6 and permitting the bus master to use the bus B2 by comparing the priority of the data transmission from the other bus master 6 requesting to use the bus B2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a bus arbitration device that assigns a bus use right to any of a plurality of bus masters, a bridge device that connects two buses, and a bus arbitration system that includes the bus arbitration device and the bridge device.

2. Description of the Related Art Conventionally, there is a bus arbitration device that selects one device and permits the use of the bus in response to a bus use request from a plurality of devices connected to one bus. As a bus arbitration system in such a bus arbitration apparatus, for example, a system disclosed in Patent Document 1 below is known. In this method, the bus arbitration device is provided with at least one timer for each bus master and a storage unit for storing the initial value of the timer, and the bus acquisition waiting time of each bus master is stored in each storage unit. When the bus use request from the bus master is notified to the device, the countdown of the timer for the bus master is started, and when the bus enters the use permission state, when there are at least two bus use requests from the bus master, A control function that compares the count values for the bus master and permits the bus master with the smallest value to use the bus, stops the countdown of the bus master that is permitted to use the bus, and returns the count value to the initial value By having the bus arbitration device hold the bus priority of each bus master, the bus master's bus acquisition waiting time is long. Automatically increases as made, it has to allow the bus arbitration control suitable for each bus master.
JP-A-3-263158

  However, there is no problem with the above method for a system configured with a single bus, but when a bus master accesses a bus slave connected to another bus in a system configured with a plurality of buses. The time taken to acquire the right to use the bus to which the bus master is connected is not taken into account for arbitration of the bus to which the bus slave is connected. Therefore, access via multiple buses takes a longer time. .

  The present invention has been made in view of the above problems, and even when accessing a bus slave via a plurality of buses, the bus can be acquired with a waiting time similar to that of accessing via a single bus. An object is to provide a bus arbitration system capable of performing the above.

  The bus arbitration system according to claim 1 is a bus arbitration system that arbitrates a bus for data transfer between a bus master connected to a first bus and a bus slave connected to a second bus. The first bus arbitration device that assigns the right to use the first bus to any one of the plurality of bus masters connected to one bus is the first to any of the plurality of bus masters connected to the first bus. Priority information created by information indicating the priority of data transfer and information on the time required to acquire the right to use the first bus for the data transfer when the right to use the bus is assigned , A transmission means for transmitting to the bridge device connected to the first bus for connecting the first bus and another bus, and the second one of the plurality of bus masters connected to the second bus. Bus use When the bridge device connected to the second bus for connecting the second bus and another bus generates a use request for the second bus as a bus master, Receiving means for receiving from the bridge device priority information created by information indicating the priority of the data transfer and information on the time required to acquire the right to use the other bus for the data transfer; Information indicating the priority of the data transfer received by the receiving unit and the priority of the data transfer from another bus master connected to the second bus requesting the use of the second bus And a permission means for selecting one bus master from a plurality of bus masters including the bridge device and permitting the bus master to use the bus.

  According to this configuration, in the data transfer performed through at least the first and second buses, the time taken to acquire another bus (at least the first bus) that has been passed to the second bus is considered. Since the right to use the second bus is assigned (the order of use is determined), data transfer across multiple buses can be performed independently for each bus without considering the previous process. Thus, the right to use the bus is not determined, and the data transfer does not take time because the data transfer is performed across a plurality of buses.

  The bus arbitration system according to claim 2 is the bus arbitration system according to claim 1, wherein the data transfer is performed via a third bus connected between the first bus and the second bus. The third bus arbitration device, which assigns the right to use the third bus to any of the plurality of bus masters connected to the third bus, connects the third bus to another bus. When the bridge device connected to the third bus for connection generates a request to use the third bus as a bus master, information indicating the priority of the data transfer and the other buses regarding the data transfer. Second priority means for receiving from the bridge device priority information created by information on the time taken to acquire the right to use, and the priority of the data transfer received by the second receiver means Information and the third And comparing the information indicating the priority of the data transfer from the other bus master connected to the third bus requesting the use of the bus to select one bus master from the plurality of bus masters including the bridge device. When the right to use the third bus is assigned to one of a plurality of bus masters connected to the third bus and the second permission means for permitting the bus master to use the third bus, the data transfer is performed. The priority information created by the information indicating the priority of the data and the time information required for acquiring the right to use the third bus for the data transfer is connected between the third bus and another bus. And a second transmission means for transmitting to the bridge device connected to the third bus.

  According to this configuration, in data transfer performed through at least the first, third, and second buses, acquisition of other buses (at least the first and third buses) that have been passed to the second bus is obtained. The right to use the second bus is assigned (the order of use is determined) in consideration of the time required for the data transfer, so even when transferring data across multiple buses, the process up to that point is not considered. The right to use the bus is not determined independently for each bus, and data transfer does not take time because the data transfer is performed across a plurality of buses.

  The bus arbitration system according to claim 3 is the bus arbitration system according to claim 1 or 2, wherein the first bus arbitration device counts down each of the bus masters connected to the first bus by counting down. A plurality of first timer means for performing, a first storage means for storing an initial value to be set in the first timer means as a priority of data transfer by each bus master connected to the first bus; An initial value stored in one storage means is set in the first timer means, and when a use request for the first bus is generated from a bus master connected to the first bus, the bus master corresponds to the bus master. First timing means for causing the first timer means to start timing, first determination means for determining whether or not the first bus is usable, and the first bus by the first determination means. Used And a first permitting means for permitting the bus master having the smallest value indicated by the first timer means to use the bus when it is determined that the transmission is possible. When one of the bus masters connected to one bus acquires the right to use the first bus, the bridge device that connects the first bus and another bus is connected to the first bus corresponding to the bus master. A value of the timer means when the right to use is acquired is transmitted, and the second bus arbitration device counts down each of the bus masters connected to the second bus by counting down a plurality of second timer means And second storage means for storing an initial value set in the second timer means as a priority of data transfer by each bus master excluding the bridge device connected to the second bus. The receiving means receives an initial value to be set in the second timer means as a priority of data transfer by the bridge apparatus from the bridge apparatus corresponding to the timer means and sets the initial value in the second timer means. The initial value stored in the second storage means is set in the second timer means, and when a request for using the second bus is generated from the bus master connected to the second bus, A second timer means for starting time measurement by a second timer means corresponding to the bus master; and a second determination means for determining whether or not the second bus is usable. When it is determined by the second determination means that the second bus is usable, the bus master having the smallest value indicated by the second timer means is permitted to use the bus. .

  According to this configuration, by setting the maximum allowable time until the bus master accesses a desired device via a plurality of buses as an initial value, arbitration of the bus is performed so that the access can be performed within the maximum allowable time. Can be done. In each bus, the value of the timer means at the time of acquisition of the bus is passed to the bridge device connected to the bus, and in the data transfer in which the bridge device becomes the bus master, the bus arbitration device of this bus receives from the bridge device. Since the value thus set is set as the initial value of the timer means, a new maximum allowable time considering the time required to acquire the bus passed before the bus can be passed to the next bus arbitration device.

  In addition, since the initial value for the bus master other than the bridge device is stored in the bus arbitration device, it is not necessary to change the initial value for each data transfer from the same bus master. There is no need to send an initial value to the bus arbitrator for each transfer. Also, the value indicated by the timer means is given as priority information created by information indicating the priority of data transfer and information on the time required to acquire the right to use one bus for the data transfer. Therefore, the priority information is composed of only one value, and the appropriate priority information can be easily created and can be easily transmitted to the next bus arbitration device.

  The bus arbitration system according to claim 4 is the bus arbitration system according to claim 2 or 3, wherein the third bus arbitration device counts down each of the bus masters connected to the third bus by counting down. A plurality of third timer means for performing, a third storage means for storing an initial value to be set in the third timer means as a priority of data transfer by each bus master connected to the third bus, A third timing start means for causing the third timer means to start timing from the initial value when a request to use the third bus is generated from a bus master connected to the second bus, and a third bus And a third determination means for determining whether or not the third bus is usable, and the second permission means, when the third determination means determines that the third bus is usable, Said third timer The bus master having the smallest value indicated by the level is allowed to use the bus, and the second transmission means obtains the right to use the third bus by any of the bus masters connected to the third bus. The third timer means corresponding to the bus master is transmitted to the bridge device that connects the third bus and the other bus when the right to use is obtained, and the second The receiving means receives the initial value set in the third timer means as the priority of data transfer by the bridge device from the bridge device corresponding to the third timer means and sets it in the timer means. is there.

  According to this configuration, the bridge device can perform the access within the maximum permissible time by setting the maximum permissible time of the remaining transfer as an initial value in consideration of the acquisition time of the bus that has passed so far. The bus can be arbitrated. In addition, since the initial value for the bus master other than the bridge device is stored in the bus arbitration device, it is not necessary to change the initial value for each data transfer from the same bus master. There is no need to send an initial value to the bus arbitrator for each transfer. Also, the value indicated by the timer means is given as priority information created by information indicating the priority of data transfer and information on the time required to acquire the right to use one bus for the data transfer. Therefore, the priority information is composed of only one value, and the appropriate priority information can be easily created and can be easily transmitted to the next bus arbitration device.

  The bus arbitration device according to claim 5 assigns the right to use the bus to any one of the plurality of bus masters in the bus arbitration device that assigns the right to use the bus to any one of the plurality of bus masters connected to the bus. The priority information created by the information indicating the priority of the data transfer and the time information required to acquire the right to use the bus for the data transfer Is provided with a transmission means for transmitting to the bridge device connected to the bus.

  According to this configuration, in data transfer performed by a bus master to / from bus slaves of other buses (that is, data transfer performed via a plurality of buses), priority is given in consideration of the time taken to acquire the bus. Since the information is transmitted to the bridge device, information on the time taken to acquire the bus can be passed to the bus arbitration device of another bus via the bridge device.

  The bus arbitration device according to claim 6 is the bus arbitration device according to claim 5, wherein each of the bus masters connected to the bus counts a plurality of timer means for counting down, and data transfer by the bus master. A storage means for storing an initial value to be set in the timer means as a priority, and an initial value stored in the storage means are set in the timer means, and when a bus use request is generated from the bus master The timer means corresponding to the bus master starts timing, the determination means for determining whether or not the bus is usable, and when the determination means determines that the bus is usable A permission means for permitting the bus master having the smallest value indicated by the timer means to use the bus, When one of the bus masters acquires the right to use the bus, the transmitting means grants the right to use the timer means corresponding to the bus master to a bridge device that connects the bus and another bus. The value at the time of acquisition is transmitted.

  According to this configuration, by setting the maximum allowable time until the bus master accesses a desired device via a plurality of buses as an initial value, arbitration of the bus is performed so that the access can be performed within the maximum allowable time. Can be done. Further, since the value of the timer means at the time when the bus is acquired in the bus is passed to the bridge device connected to the bus, the remaining time of the maximum allowable time can be passed to the next bus arbitration device.

  In addition, since the initial value for the bus master other than the bridge device is stored in the bus arbitration device, it is not necessary to change the initial value for each data transfer from the same bus master. There is no need to send an initial value to the bus arbitrator for each transfer. Also, the value indicated by the timer means is given as priority information created by information indicating the priority of data transfer and information on the time required to acquire the right to use one bus for the data transfer. Therefore, the priority information is composed of only one value, and the appropriate priority information can be easily created and can be easily transmitted to the next bus arbitration device.

  The bus arbitration device according to claim 7 is a bus arbitration device that assigns the right to use the bus to any of a plurality of bus masters connected to the bus, and the bus for connecting the bus to another bus. When the connected bridge device generates a request to use the bus as a bus master, information indicating the priority of the data transfer and the time required to acquire the right to use the other bus for the data transfer Receiving means for receiving priority information created by the information from the bridge device, the priority information received by the receiving means from the priority information of the data transfer, and from another bus master requesting use of the bus Compared with the information indicating the priority of data transfer, one bus master is selected from a plurality of bus masters including the bridge device, and the bus master is selected. Serial in which and a permitting means for permitting the use of the bus.

  According to this configuration, in data transfer performed by the bus master to / from bus slaves of other buses (that is, data transfer performed via a plurality of buses), it is necessary to acquire another bus up to the bus. Since the priority information considering the time is received from the bridge device connected to the bus, the right to use the second bus is assigned in consideration of the time taken to acquire another bus (the order of use is determined). Data transfer across multiple buses without determining the right to use the bus independently for each bus without considering the previous process in data transfer across multiple buses Therefore, it does not take time to transfer data.

  A bus arbitration device according to claim 8 is the bus arbitration device according to claim 7, wherein each of the bus masters connected to the bus is connected to the bus by a plurality of timer means for counting time by countdown. Storage means for storing an initial value to be set in the timer means as a priority of data transfer by each bus master excluding the bridge device, and the receiving means has the timer means as a priority of data transfer by the bridge device The initial value to be set in the timer means is received from the bridge device corresponding to the timer means, set in the timer means, the initial value stored in the storage means is set in the timer means, and connected to the bus When a bus use request is generated from a bus master, the timer means corresponding to the bus master starts timing. A timing start unit for determining whether or not the bus is usable, and the permitting unit includes the timer unit when the determination unit determines that the bus is usable. The bus master having the smallest value indicated by is permitted to use the bus.

  According to this configuration, the bridge device transmits to the bus arbitration device the maximum allowable time obtained by subtracting the time required to acquire another bus that has reached the bus, so that the access is performed within the maximum allowable time. You can arbitrate the bus as you can. In addition, since the initial value for the bus master other than the bridge device is stored in the bus arbitration device, it is not necessary to change the initial value for each data transfer from the same bus master. There is no need to send an initial value to the bus arbitrator for each transfer. Also, the value indicated by the timer means is given as priority information created by information indicating the priority of data transfer and information on the time required to acquire the right to use one bus for the data transfer. Therefore, the priority information is composed of only one value, and the appropriate priority information can be easily created and can be easily transmitted to the next bus arbitration device.

  The bus arbitration device according to claim 9 is a bus arbitration device that assigns the right to use the bus to any one of a plurality of bus masters connected to the bus, and the bus for connecting the bus to another bus. When the connected bridge device generates a request to use the bus as a bus master, information indicating the priority of the data transfer and the time required to acquire the right to use the other bus for the data transfer Receiving means for receiving priority information created by the information from the bridge device; the priority information for the data transfer received by the receiving means; and connected to the bus requesting use of the bus Compare the information indicating the priority of data transfer from other bus masters to select one bus master from a plurality of bus masters including the bridge device. Permission means for permitting the bus master to use the bus, and information indicating the priority of data transfer when the right to use the bus is assigned to any of a plurality of bus masters connected to the bus; Priority information created by information on the time required to acquire the right to use the bus for the data transfer is transmitted to a bridge device connected to the bus for connecting the bus to another bus. Transmitting means.

  According to this configuration, it is possible to provide a bus arbitration device that achieves the effects of claims 5 and 7.

  The bus arbitration device according to claim 10 is the bus arbitration device according to claim 9, wherein each of the bus masters connected to the bus has a plurality of timer means for counting time by countdown, and is connected to the bus Storage means for storing an initial value set in the timer means as a priority of data transfer by each bus master, and when the bus use request is generated from the bus master connected to the bus, the timer means A timing start unit for starting timing from the value; and a determination unit for determining whether or not the bus can be used; and the permission unit is determined by the determination unit that the bus is usable When the bus master having the smallest value indicated by the timer means is permitted to use the bus, the transmitting means is connected to the bus. When one of the bus masters has acquired the right to use the bus, the value when the right to use the timer means corresponding to the bus master is acquired in a bridge device that connects the bus and another bus. The receiving means receives an initial value set in the timer means as a priority of data transfer by the bridge device from the bridge device corresponding to the timer means and sets it in the timer means. .

  According to this configuration, it is possible to provide a bus arbitration device that achieves the effects of claims 6 and 8.

  The bridge device according to claim 11 is a bridge device that connects two buses, and requests the bus arbitration device of the other bus to arbitrate the value received from the bus arbitration device of one bus. And transmitting means for converting the bus data input from one bus into bus data suitable for the other bus and outputting the bus data to the other bus.

  According to this configuration, the priority information created by the information indicating the priority of data transfer and the information of the time required to acquire the right to use one bus for the data transfer is converted into the bus of one bus. Since it is received from the arbitration device and transmitted to the bus arbitration device of another bus, it is possible to consider the time required to acquire the right to use one bus in the arbitration of another bus.

  According to the first aspect of the present invention, in the data transfer performed through at least the first and second buses, another bus (at least the first bus) that has been passed to the second bus is obtained. The right to use the second bus is assigned in consideration of the time taken (the order of use is determined), so even when transferring data across multiple buses, The right to use the bus is not determined independently for each bus, and data transfer does not take time because it is data transfer across a plurality of buses.

  According to the second aspect of the present invention, in the data transfer performed through at least the first, third, and second buses, the other buses that have passed to the second bus (at least the first and third buses). The right to use the second bus is considered and the right to use the second bus is assigned (the order of use is determined), so even in the data transfer across multiple buses, The right to use the bus is not determined independently for each bus without considering the above, and the data transfer does not take time because the data transfer is performed across a plurality of buses.

  According to the third aspect of the present invention, the bus master can set the maximum allowable time until accessing a desired device via a plurality of buses as an initial value, so that the access can be performed within the maximum allowable time. So that the bus can be adjusted. In each bus, the value of the timer means at the time of acquisition of the bus is passed to the bridge device connected to the bus, and in the data transfer in which the bridge device becomes the bus master, the bus arbitration device of this bus receives from the bridge device. Since the value thus set is set as the initial value of the timer means, a new maximum allowable time considering the time required to acquire the bus passed before the bus can be passed to the next bus arbitration device. In addition, since the initial value for the bus master other than the bridge device is stored in the bus arbitration device, it is not necessary to change the initial value for each data transfer from the same bus master. There is no need to send an initial value to the bus arbitrator for each transfer. Also, the value indicated by the timer means is given as priority information created by information indicating the priority of data transfer and information on the time required to acquire the right to use one bus for the data transfer. Therefore, the priority information is composed of only one value, and the appropriate priority information can be easily created and can be easily transmitted to the next bus arbitration device.

  According to the invention described in claim 4, the bridge device sets the maximum allowable time of the remaining transfer in consideration of the acquisition time of the bus that has passed so far as an initial value. The bus can be arbitrated so that the access can be made. In addition, since the initial value for the bus master other than the bridge device is stored in the bus arbitration device, it is not necessary to change the initial value for each data transfer from the same bus master. There is no need to send an initial value to the bus arbitrator for each transfer. Also, the value indicated by the timer means is given as priority information created by information indicating the priority of data transfer and information on the time required to acquire the right to use one bus for the data transfer. Therefore, the priority information is composed of only one value, and the appropriate priority information can be easily created and can be easily transmitted to the next bus arbitration device.

  According to the fifth aspect of the present invention, in the data transfer performed by the bus master with the bus slaves of other buses (that is, the data transfer performed via a plurality of buses), it is necessary to acquire the bus. Since the priority information considering the time is transmitted to the bridge device, information on the time taken to acquire the bus can be passed to the bus arbitration device of another bus via the bridge device.

  According to the invention described in claim 6, the bus master can set the maximum allowable time until accessing a desired device via a plurality of buses as an initial value, so that the access can be performed within the maximum allowable time. So that the bus can be adjusted. Further, since the value of the timer means at the time when the bus is acquired in the bus is passed to the bridge device connected to the bus, the remaining time of the maximum allowable time can be passed to the next bus arbitration device. In addition, since the initial value for the bus master other than the bridge device is stored in the bus arbitration device, it is not necessary to change the initial value for each data transfer from the same bus master. There is no need to send an initial value to the bus arbitrator for each transfer. Also, the value indicated by the timer means is given as priority information created by information indicating the priority of data transfer and information on the time required to acquire the right to use one bus for the data transfer. Therefore, the priority information is composed of only one value, and the appropriate priority information can be easily created and can be easily transmitted to the next bus arbitration device.

  According to the seventh aspect of the present invention, in the data transfer performed by the bus master with the bus slave of another bus (that is, data transfer performed via a plurality of buses), the other bus up to the bus Since priority information that takes into account the time taken to acquire the bus is received from the bridge device connected to the bus, the right to use the second bus is assigned in consideration of the time taken to acquire another bus. (The order of use is determined) Even in data transfer across multiple buses, the right to use the bus is not determined independently for each bus without considering the previous process. Therefore, the data transfer does not take time.

  According to the invention described in claim 8, since the bridge device transmits the maximum allowable time obtained by subtracting the time required to acquire another bus that has reached the bus to the bus arbitration device. The bus can be arbitrated so that the above access can be made. In addition, since the initial value for the bus master other than the bridge device is stored in the bus arbitration device, it is not necessary to change the initial value for each data transfer from the same bus master. There is no need to send an initial value to the bus arbitrator for each transfer. Also, the value indicated by the timer means is given as priority information created by information indicating the priority of data transfer and information on the time required to acquire the right to use one bus for the data transfer. Therefore, the priority information is composed of only one value, and the appropriate priority information can be easily created and can be easily transmitted to the next bus arbitration device.

  According to invention of Claim 9, the bus arbitration apparatus which has the effect of Claim 5 or 7 can be provided.

  According to invention of Claim 10, the bus arbitration apparatus which has the effect of Claim 6 or 8 can be provided.

  According to the eleventh aspect of the invention, the priority information created by the information indicating the priority of the data transfer and the information of the time required to acquire the right to use one bus for the data transfer, Since it is received from the bus arbitration device of one bus and transmitted to the bus arbitration device of the other bus, it takes into account the time taken to acquire the right to use one bus in the arbitration of the other bus it can.

  Hereinafter, a bus arbitration system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a hardware configuration diagram schematically showing the configuration of a bus arbitration system 1 according to an embodiment of the present invention. The bus arbitration system 1 includes a bus B1, a bus B2, a bus arbiter 2, a bus master 3, a bus master 4, a bridge 5, a bus master 6, a bus slave 7, and a bus arbiter 8. A bus arbiter 2, a bus master 3, a bus master 4, and a bridge 5 are connected to the bus B1. A bridge 5, a bus master 6, a bus slave 7, and a bus arbiter 8 are connected to the bus B2. The bus arbiter 2 includes a bus use request line (not shown), a bus use permission line (not shown), and a bus use end line (not shown) as dedicated lines between the bus masters 3 and 4. The bus arbiter 2 includes a remaining timer value transmission line (not shown) as a dedicated line between the bus arbiter 2 and the bridge 5. The bus arbiter 8 includes a bus use request line, a bus use permission line, and a bus use end line as dedicated lines between the bridges 5 and the bus master 6.

  The bus arbiter 2 is a bus arbitration device that determines the right to use the bus B1 to one of the bus masters 3 and 4 connected to the bus B1. The configuration of the bus arbiter 2 will be described later. The bus master 3 and the bus master 4 are devices that become bus masters in the bus B1, and are devices that read and write data to, for example, a memory (for example, the bus slave 7). The bridge 5 is a device for connecting the bus B1 and the bus B2, and converts data on the bus B1 into data on the bus B2 and outputs the data to the bus B2. The bridge 5 becomes a bus slave in the bus B1 and becomes a bus master in the bus B2. The configuration of the bridge 5 will be described later.

  The bus arbiter 8 is a bus arbitration device that determines the right to use the bus B2 for any of the bus masters (the bridge 5 and the bus master 6) connected to the bus B2. The configuration of the bus arbiter 8 will be described later. The bus master 6 is a device that becomes a bus master in the bus B2, and is a device that reads and writes data from, for example, a memory (for example, a bus slave 7). The bus slave 7 is a device that becomes a bus slave in the bus B2, and is, for example, a memory.

  Next, functions of the bus arbiter 2, the bridge 5, and the bus arbiter 8 will be described with reference to FIGS. FIG. 2 is a block diagram showing a functional configuration of the bus arbiter 2. The bus arbiter 2 includes an initial value storage unit 21, an initial value storage unit 22, a timer unit 23, a timer unit 24, a bus waiting list storage unit 25, an arbitration control unit 26, and a bus state management unit 27. The initial value storage unit 21 stores a maximum bus waiting allowable time of the bus master 3 that is used as an initial value of the timer unit 23. The initial value storage unit 22 stores the maximum bus waiting allowable time of the bus master 4 used as an initial value of the timer unit 24. The timer unit 23 measures time for the bus master 3, and when the arbitration control unit 26 is instructed to start timing, the timer unit 23 reads the initial value from the initial value storage unit 21, counts down from the initial value, and counts time. The timer unit 24 measures time for the bus master 4, and when the arbitration control unit 26 is instructed to start timing, the timer unit 24 reads the initial value from the initial value storage unit 22, counts down from the initial value, and counts time. These timer units 23 and 24 read values from the initial value storage units 21 and 22 and set them in the timer units 23 and 24 as initial values when the bus arbitration system 1 is started and timed.

  The bus wait list storage unit 25 stores a list of bus masters (bus master 3 and bus master 4) that are in a bus wait state (that has issued a bus use request and has not yet received a bus use permission). The arbitration control unit 26 controls bus adjustment. When there is a bus use request line turned on, the arbitration control unit 26 identifies the bus master 3 or 4 with the bus use request line turned on, and sends it to the timer unit 23 or 24 corresponding to the bus master 3 or 4. An instruction to start timing is issued, and the bus master 3 or 4 is registered in the bus waiting list storage unit 25. Next, the arbitration control unit 26 inquires of the bus state management unit 27 whether or not the bus is free. If the bus is free, the timer value of the bus master stored in the bus waiting list storage unit 25 is set as a timer. The bus use permission line for the bus master having the smallest timer value read from the unit 23 and / or the timer unit 24 is turned on, and information indicating that the bus is started to be used is transmitted to the bus state management unit 27. In addition, at this time, the timer value is output to the remaining timer value transmission line and transmitted to the bridge 5. Further, even when the arbitration control unit 26 receives information from the bus state management unit 27 that the bus has been released, the arbitration control unit 26 performs processing when the bus is free.

  The bus state management unit 27 determines whether or not the bus is in use based on the fact that the use start of the bus is received from the arbitration control unit 26 and the bus use end line is turned on. It holds information and responds to inquiries from the arbitration control unit 26 regarding bus availability. When the bus use end line is turned on, the fact that the bus is released is transmitted to the arbitration control unit 26.

  FIG. 3 is a block diagram showing a functional configuration of the bridge 5. The bridge 5 includes an initial value setting unit 51, a bus use control unit 52, and a data conversion unit 53. When the initial value setting unit 51 receives a timer value from the remaining timer value transmission line, the initial value setting unit 51 stores and holds the timer value. When the initial value setting unit 51 is instructed by the bus use control unit 52 to set the initial value, the initial value setting unit 51 outputs the held timer value to the initial value transmission line and transmits it to the bus arbiter 8.

  When the bus use control unit 52 receives that data has been input from the data conversion unit 53, the bus use control unit 52 instructs the initial value setting unit 51 to set an initial value, turns on the bus use request line, and sends a bus to the bus arbiter 8. Make a usage request. Thereafter, the bus use control unit 52 instructs the data conversion unit 53 to output the data input from the bus B1 to the bus B2 when the bus use permission line is turned on. In addition, the bus use control unit 52 turns on the bus use end line when receiving a message indicating that the data output from the data conversion unit 53 to the bus B2 has ended.

  When data is input from the bus B1, the data conversion unit 53 transmits the fact to the bus use control unit 52. Further, when the data conversion unit 53 is instructed to output the data input from the bus B1 to the bus B2 from the bus use control unit 52, the data conversion unit 53 converts the data input from the bus B1 to the bus B2. To the bus B2. When this output is completed, the data conversion unit 53 sends a notification to the bus usage control unit 52 that the data output has been completed.

  FIG. 4 is a block diagram showing a functional configuration of the bus arbiter 8. The bus arbiter 8 includes an initial value storage unit 81, an initial value setting unit 82, a timer unit 83, a timer unit 84, a bus waiting list storage unit 85, an arbitration control unit 86, and a bus state management unit 87. The initial value storage unit 81, timer unit 83, timer unit 84, bus wait list storage unit 85, and bus state management unit 87 are the initial value storage unit 21, timer unit 23, timer unit 24, and bus wait list storage of the bus arbiter 2. Since it is the same as the unit 25 and the bus state management unit 27 (however, the connection destination of the dedicated line is different), the description thereof is omitted.

  The initial value setting unit 82 receives and stores the initial value of the timer unit 84 from the bridge 5 through the initial value transmission line. The arbitration control unit 86 is substantially the same as the arbitration control unit 26 of the bus arbiter 2 except that the remaining timer value transmission line is not connected and the remaining timer value is not transmitted.

  Next, an arbitration operation related to data access in the bus arbitration system 1 via the two buses B1 and B2 will be described using an example. As an example, an operation of writing data from the bus master 3 (data writing device) to the bus slave 7 (memory) will be described. FIG. 5 is a flowchart showing the operation of the bus arbitration system in this example.

  In the bus master 3, first, the bus use request line is turned on to request the bus arbiter 2 to use the bus (step S31). Then, it is checked whether or not the bus use permission line is turned on (step S32). If the bus use permission line is turned on (YES in step S32), the address and write data to be written are stored in the bus B1. (Step S33), the bus use end line is turned on to release the bus (step S34). Since this address on the bus B1 is the address of the bridge 5, data is taken into the bridge 5.

  In the bus arbiter 2, when the arbitration control unit 26 detects that the bus use request line is turned on, the arbitration control unit 26 identifies that the bus master to which the bus use request line is connected is the bus master 3, and the bus master 3 It is recognized that there has been a bus use request (YES in step S21). Then, the arbitration control unit 26 inquires of the bus state management unit 27 whether or not the bus is in use (step S22). If the bus is not in use (NO in step S22), the bus master 3 is turned on (step S27), the timer value (in this case, the initial value) set in the timer unit 23 corresponding to the bus master 3 is read, and the remaining timer value is transmitted. Output to the line (step S28).

  As a result of the inquiry to the bus state management unit 27, if the bus is in use (YES in step S22), the arbitration control unit 26 adds the bus master 3 to the bus waiting list storage unit 25, and the bus master. 3 is instructed to start time measurement to the timer unit 23 corresponding to the timer No. 3. In response to the instruction from the arbitration control unit 26, the timer unit 23 counts down from the initial value that has already been set and starts measuring time (step S23). The arbitration control unit 26 checks whether or not the bus state management unit 27 reports that the bus B1 has been released (NO in step S24), and sends a report that the bus has been released from the bus state management unit 27. If received (YES in step S24), the bus waiting list storage unit 25 is checked, and if there is only one bus master in the bus waiting list storage unit 25 (NO in step S25), the bus master (for example, bus master) 3) The bus use permission line connected to 3) is turned on (step S27), and the timer value (initial value in this case) set in the timer unit 23 which is a timer unit corresponding to the bus master 3, for example, is read. The value is output to the value transmission line (step S28).

  If there are a plurality of bus masters in the bus waiting list storage unit 25 (YES in step S25), the current timer values are read from the timer units 23 and 24 corresponding to those bus masters (for example, bus masters 3 and 4), and the timer values are read. The bus use permission line connected to the bus master corresponding to the smaller one (for example, bus master 3) is turned on (steps S26 and S27), and the timer value (initial value in this case) set in the timer unit 23 is read. Output to the remaining timer value transmission line (step S28).

  In the bridge 5, the initial value setting unit 51 receives the timer value transmitted from the bus arbiter 2 (YES in step S51), and stores and holds it as a remaining timer value (step S52). Thereafter, the bus use control unit 52 receives the transfer data from the bus master 3 by the data conversion unit 53 (YES in step S53), and acquires the right to use the bus B2. Since the operation flow (steps S54 to S56 and steps S81 to S88) related to the acquisition of the right to use the bus B2 in the bridge 5 is the same as that in the case of the bus B1, description thereof will be omitted. However, the initial value setting unit 51 outputs the remaining timer value stored and held to the initial value transmission line to the bus arbiter 8 after the bus use control unit 52 turns on the bus use request line (step S54). Transmit (step S55). The initial value setting unit 82 of the bus arbiter 8 receives this and sets it in the timer unit 84. When the bus use control unit 52 obtains the right to use the bus B2 (YES in step S56), it converts the contents of the address bus input from the bus master 3 for the bus B2, and receives the address and the data received from the bus B2. Is output to the bus B2 (step S57). When the data is output to the bus B2, the bus use control unit 52 releases the bus by turning on the bus use end line (step S58).

  The bus slave 7 takes in the data output to the bus B2 to the address output to the bus B2. The bus arbiter 8 does not perform the operation corresponding to step S28 of the bus arbiter 2.

  As described above, according to the present embodiment, the remaining timer value in the arbitration of the bus B1 (timer value when the bus use right is acquired) is transmitted to the bridge 5, and the bridge 5 transmits the timer value to the bus B2. Since the bus arbiter 8 is set as the initial value of the timer value in the arbitration, the arbitration of the bus B2 is performed with a priority in consideration of the time taken for the arbitration of the bus B1.

  In addition, this invention is not limited to the thing of the said embodiment, The aspect described below can be employ | adopted. In the present embodiment, in the bus arbiters 2 and 8 (bus arbitration device), the maximum allowable time for access to the target bus slave is set to an initial value, and the timer units 23, 24, 83, and 84 However, the initial value does not necessarily need to be the maximum allowable time, and may be a numerical value indicating the priority of bus use, for example. In this case, a small initial value is set for a high priority, and the bus master having the smallest timer value is given to the bus master when the bus becomes free. Alternatively, the timer units 23, 24, 83, and 84 may count up from the initial values. In this case, the priority is set to the initial value, the higher initial value is set to the higher priority, and the right to use the bus is given to the bus master having the largest timer value when the bus becomes free. Should be given.

  Further, in the present embodiment, the bus arbiter 2 transmits a time obtained by subtracting the bus waiting time from the initial time value (timer value at the time when the bus is allocated) to the bridge 5, and the bridge 5 The initial value of the bus arbitration is transmitted to the bus arbiter 8, but the priority is used instead of the initial value, and the waiting time is counted by the timer units 23 and 24 separately from the priority, and the priority and the timer value are obtained. In both cases, the bridge 5 may be measured and transmitted to the bus arbiter 8. In this case, the right to use the bus is determined in consideration of the priority and the waiting time (timer value) (for example, by subtracting the waiting time from the priority), and the priority and the waiting time are bridged. 5 to the bus arbiter 8, and the bus arbiter 8 may determine the right to use the bus B2 in consideration of the total waiting time (in the buses B1 and B2) and the priority.

  In this embodiment, the initial value for the bus master other than the bridge is stored in the bus arbiter. However, the initial value may be transmitted from the bus master to the bus arbiter even for a bus master other than the bridge.

  In this embodiment, the case where the bus master 3 accesses the bus slave 7 via the two buses B1 and B2 has been described as an example, but the case where the bus master accesses the bus slave via three or more buses is also described. The present invention can be applied. In this case, the bus arbiter (bus arbiter) of the bus on the way is the function of both the bus arbiter 2 and the bus arbiter 8 of this embodiment (that is, the function of transmitting the remaining timer value to the bridge device and the remaining timer received from the bridge device). And a function for setting a value as an initial value of the timer unit).

It is a hardware block diagram which shows the structure of the bus arbitration system in one Embodiment of this invention. It is a block diagram which shows the function structure of the bus arbiter of the bus | bath to which the bus master was connected in one Embodiment of this invention. It is a block diagram which shows the function structure of the bridge | bridging in one Embodiment of this invention. It is a block diagram which shows the function structure of the bus arbiter of the bus | bath to which the bus slave was connected in one Embodiment of this invention. It is a flowchart which shows the flow of the bus arbitration operation | movement in one Embodiment of this invention.

Explanation of symbols

1 Bus Arbitration System 2, 8 Bus Arbiter (Bus Arbiter)
21, 22, 81 Initial value storage unit (storage means)
23, 24, 83, 84 Timer part (timer means)
26 Arbitration control unit (permission means, timing start means, timer value transmission means)
3, 4, 6 Bus master 5 Bridge (Bus master, Bridge device)
51 Initial value setting section (transmission means)
53 Data converter (converter)
82 Initial value setting unit (priority information acquisition means, initial value setting means)
86 Mediation control unit (permission means, timing start means)
87 Bus state manager (determination means)
B1, B2 bus

Claims (11)

In a bus arbitration system that arbitrates a bus for data transfer between a bus master connected to a first bus and a bus slave connected to a second bus,
A first bus arbitration device that assigns the right to use the first bus to any one of the plurality of bus masters connected to the first bus,
When the right to use the first bus is assigned to one of a plurality of bus masters connected to the first bus, information indicating the priority of the data transfer and use of the first bus for the data transfer Transmission means for transmitting priority information created by information on the time required to acquire the right to a bridge device connected to the first bus for connecting the first bus to another bus Prepared,
A second bus arbitration device that assigns the right to use the second bus to any of a plurality of bus masters connected to the second bus,
Information indicating the priority of data transfer when a bridge device connected to the second bus for connecting the second bus and another bus generates a request to use the second bus as a bus master; Receiving means for receiving, from the bridge device, priority information created by information on the time required to acquire the right to use the other bus for the data transfer;
Information indicating the priority of the data transfer received by the receiving unit and the priority of the data transfer from another bus master connected to the second bus requesting the use of the second bus And a permitting means for selecting one bus master from a plurality of bus masters including the bridge device and permitting the bus master to use the bus. The data transfer is performed via a third bus connected between the first bus and the second bus,
A third bus arbitration device that assigns the right to use the third bus to any one of the plurality of bus masters connected to the third bus,
Information indicating the priority of data transfer when a bridge device connected to the third bus for connecting the third bus and another bus generates a request to use the third bus as a bus master; A second receiving means for receiving, from the bridge device, priority information created by information on the time required to acquire the right to use the other bus for the data transfer;
The priority information of the data transfer received by the second receiving means and the priority of data transfer from another bus master connected to the third bus requesting use of the third bus A second permission means for selecting one bus master from a plurality of bus masters including the bridge device and permitting the bus master to use the third bus;
When the right to use the third bus is assigned to any of a plurality of bus masters connected to the third bus, information indicating the priority of the data transfer and the right to use the third bus for the data transfer 2nd transmission which transmits the priority information created by the information of the time required to acquire the second bus to the bridge device connected to the third bus for connecting the third bus to another bus The bus arbitration system according to claim 1, further comprising: means. The first bus arbitration device includes:
A plurality of first timer means for measuring time by countdown for each of the bus masters connected to the first bus;
First storage means for storing an initial value to be set in the first timer means as a priority of data transfer by each bus master connected to the first bus;
The initial value stored in the first storage means is set in the first timer means, and when a use request for the first bus is generated from the bus master connected to the first bus, the bus master First timer start means for causing the first timer means corresponding to to start timing;
First determination means for determining whether the first bus is usable;
When it is determined by the first determination means that the first bus is usable, the bus master having the smallest value indicated by the first timer means is permitted to use the bus. A permission means,
When one of the bus masters connected to the first bus has acquired the right to use the first bus, the transmission means is connected to the bridge device that connects the first bus to another bus. Transmitting the value of the corresponding first timer means when the usage right is acquired;
The second bus arbitration device is:
A plurality of second timer means for measuring time by countdown for each of the bus masters connected to the second bus;
Second storage means for storing an initial value set in the second timer means as a priority of data transfer by each bus master except for the bridge device connected to a second bus;
The receiving means receives an initial value set in the second timer means as a priority of data transfer by the bridge device from the bridge device corresponding to the timer means, and sets the initial value in the second timer means,
The initial value stored in the second storage means is set in the second timer means, and when a use request for the second bus is generated from the bus master connected to the second bus, the bus master Second timing start means for causing the second timer means corresponding to to start timing;
And a second determination means for determining whether or not the second bus is usable,
When the second determination unit determines that the second bus can be used, the permission unit allows the bus master having the smallest value indicated by the second timer unit to use the bus. The bus arbitration system according to claim 1 or 2, wherein the bus arbitration system is permitted. The third bus arbitration device is:
A plurality of third timer means for measuring time by countdown for each of the bus masters connected to the third bus;
Third storage means for storing an initial value set in the third timer means as a priority of data transfer by each bus master connected to the third bus;
Third timing start means for causing the third timer means to start timing from the initial value when a request to use the third bus is generated from a bus master connected to the third bus;
And a third determination means for determining whether or not the third bus is usable,
When the third determination unit determines that the third bus is usable, the second permission unit sends the bus master having the smallest value indicated by the third timer unit to the bus master. Allow the use of
When the second transmission unit acquires a right to use the third bus when any of the bus masters connected to the third bus acquires a bridge device that connects the third bus to another bus, Sending the value of the third timer means corresponding to the bus master when the right to use is acquired;
The second receiving means receives an initial value set in the third timer means as a priority of data transfer by the bridge device from the bridge device corresponding to the third timer means, and receives the initial value to the timer means. The bus arbitration system according to claim 2 or 3, wherein the bus arbitration system is set. In the bus arbitration device that assigns the right to use the bus to any of a plurality of bus masters connected to the bus,
When the right to use the bus is assigned to one of the plurality of bus masters, information indicating the priority of the data transfer, and information on the time required to acquire the right to use the bus for the data transfer; A bus arbitration device comprising transmission means for transmitting the priority information created by the above-mentioned information to a bridge device connected to the bus for connecting the bus to another bus. A plurality of timer means for measuring time by countdown for each of the bus masters connected to the bus;
Storage means for storing an initial value set in the timer means as a priority of data transfer by the bus master;
Time setting start means for setting the initial value stored in the storage means to the timer means and causing the timer means corresponding to the bus master to start timing when a request to use the bus is generated from the bus master; ,
Determining means for determining whether the bus is usable;
A permission means for permitting the bus master having the smallest value indicated by the timer means to use the bus when the determination means determines that the bus is usable;
When one of the bus masters obtains the right to use the bus, the transmitting means grants the right to use the timer means corresponding to the bus master to a bridge device that connects the bus and another bus. 6. The bus arbitration device according to claim 5, wherein a value when acquired is transmitted. In the bus arbitration device that assigns the right to use the bus to any of a plurality of bus masters connected to the bus,
When a bridge device connected to the bus for connecting the bus and another bus generates a use request for the bus as a bus master, information indicating the priority of the data transfer, and the data transfer Receiving means for receiving from the bridge device priority information created by information on the time required to acquire the right to use another bus;
Comparing the priority information of the data transfer received by the receiving means with information indicating the priority of the data transfer from another bus master requesting the use of the bus; A bus arbitration device comprising: a permission unit that selects one bus master from a plurality of bus masters and permits the bus master to use the bus. A plurality of timer means for measuring time by countdown for each of the bus masters connected to the bus;
Storage means for storing an initial value set in the timer means as a priority of data transfer by each bus master excluding the bridge device connected to the bus;
The receiving means receives an initial value set in the timer means as a priority of data transfer by the bridge device from the bridge device corresponding to the timer means, and sets the timer means in the timer means,
The initial value stored in the storage unit is set in the timer unit, and when a bus use request is generated from a bus master connected to the bus, the timer unit corresponding to the bus master starts timing. Timing start means to be
Determination means for determining whether or not the bus is usable,
8. The permission unit according to claim 7, wherein when the determination unit determines that the bus is usable, the permission unit permits the bus master having the smallest value indicated by the timer unit to use the bus. Bus arbitrator. In the bus arbitration device that assigns the right to use the bus to any of a plurality of bus masters connected to the bus,
When a bridge device connected to the bus for connecting the bus and another bus generates a use request for the bus as a bus master, information indicating the priority of the data transfer, and the data transfer Receiving means for receiving from the bridge device priority information created by information on the time required to acquire the right to use another bus;
The priority information of the data transfer received by the receiving means is compared with information indicating the priority of the data transfer from another bus master connected to the bus requesting use of the bus. A permission means for selecting one bus master from a plurality of bus masters including the bridge device and permitting the bus master to use the bus;
When the right to use the bus is assigned to one of a plurality of bus masters connected to the bus, information indicating the priority of the data transfer and the right to use the bus for the data transfer are required. A bus arbitration device comprising: transmission means for transmitting priority information generated by the time information to a bridge device connected to the bus for connecting the bus and another bus. A plurality of timer means for measuring time by countdown for each of the bus masters connected to the bus;
Storage means for storing an initial value set in the timer means as a priority of data transfer by each bus master connected to the bus;
When a request for use of the bus is generated from a bus master connected to the bus, the timer means starts timing from the initial value to the timer means;
Determination means for determining whether or not the bus is usable,
The permission means permits the bus master having the smallest value indicated by the timer means to use the bus when the determination means determines that the bus is usable.
When one of the bus masters connected to the bus acquires the right to use the bus, the transmission means transmits a bridge device that connects the bus and another bus to the timer means corresponding to the bus master. , Send the value when the right to use is acquired,
10. The bus according to claim 9, wherein the receiving unit receives an initial value set in the timer unit as a priority of data transfer by the bridge device from the bridge device corresponding to the timer unit and sets the initial value in the timer unit. Arbitration device. In a bridge device connecting two buses,
A transmission means for transmitting the value received from the bus arbitration device of one bus to this bus arbitration device when requesting arbitration to the bus arbitration device of the other bus;
A bridge device comprising: conversion means for converting bus data input from one bus into bus data suitable for the other bus and outputting the bus data to the other bus.

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