JP2014106868A - Semiconductor device, image forming apparatus, and access control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device, an image forming apparatus, and an access control method capable of appropriately controlling, when a single resource is accessed by a plurality of arithmetic processing devices, contention of access without uniformly decreasing priority of preceding processing.SOLUTION: When a semiconductor device of the present invention receives requests to access an external storage device from a plurality of arithmetic processing devices included in the semiconductor device, and receives an access request from an arithmetic processing device performing plotter output processing, determines whether a predetermined standby time has elapsed, and when the standby time has elapsed, permits access to the external storage device to the arithmetic processing device performing plotter output processing.

Description

  The present invention relates to an access control technique, and more particularly to a semiconductor device, an image forming apparatus, and an access control method for controlling access to a common resource from a plurality of arithmetic processing devices.

  Conventionally, an image forming apparatus such as an MFP (Multi Function Peripheral) equipped with an LSI (Large Scale Integrated) in which a plurality of arithmetic processing devices access resources such as an external storage device has been used. In such an image forming apparatus, since a plurality of arithmetic processing devices access the same resource at an arbitrary timing, an access control technique for exclusively controlling a plurality of accesses occurring at the same time is required.

  As an example of a conventional access control technique, Patent Document 1 stops execution of a previous process that has already been executed when a subsequent process with a high priority occurs, and assigns resources to the subsequent process with a high priority and executes the process. Subsequently, an exclusive control method for resuming execution of the preceding process will be disclosed.

  However, in the exclusive control method disclosed in Patent Document 1, exclusive control is uniformly performed according to a predetermined priority, and therefore it is not necessary to lower the priority of the preceding process in order to execute a subsequent process having a high priority. Even in the situation, there is a problem that the priority of the preceding process is uniformly lowered and the preceding process is always delayed.

  In particular, when the above exclusive control method is applied to an image forming apparatus that needs to acquire image data from a resource and draw a predetermined amount of image data on a sheet within a predetermined time, it depends on the generation timing of the plotter output process of the image data. However, although it is not necessary to lower the priority of the preceding process, the access to the resource accompanying the plotter output process is always prioritized over other processes using the resource. For this reason, the conventional exclusive control method that lowers the priority uniformly has a problem that other processes with low priority are always delayed.

  The present invention has been made in view of the above-described problems of the prior art, and when the same resource is accessed from a plurality of arithmetic processing devices, it uniformly lowers the priority of the preceding processing. An object of the present invention is to provide a semiconductor device, an image forming apparatus, and an access control method that can appropriately control competing accesses.

  In order to solve the above problems, a semiconductor device according to the present invention includes a case where there is an access request to a storage device from a plurality of arithmetic processing devices included in the semiconductor device, and the arithmetic processing device that executes plotter output processing. When there is an access request, it is determined whether a predetermined standby time has elapsed, and when the standby time has elapsed, the arithmetic processing unit that executes the plotter output process is permitted to access the storage device.

  By adopting the above configuration requirements, the present invention allows competing accesses without lowering the priority of the preceding process uniformly when accesses from a plurality of arithmetic processing devices occur for the same resource. Can be controlled appropriately.

1 is a diagram showing a system configuration of an image forming apparatus of the present invention. FIG. 4 is a diagram illustrating a functional configuration of an access control unit included in the semiconductor device of the present invention. FIG. 6 is a diagram showing a functional configuration of an external storage device I / F included in the semiconductor device of the present invention. FIG. 4 is a sequence diagram showing access control processing executed by the image forming apparatus of the present invention. 6 is a flowchart showing processing executed by an access control unit included in the semiconductor device of the present invention. 6 is a flowchart showing processing executed by an external storage device interface included in the semiconductor device of the present invention. FIG. 4 is a diagram illustrating a relationship between a state of processing executed by the image forming apparatus of the present invention and signals and notifications processed by the image forming apparatus.

  Hereinafter, although this invention is demonstrated with embodiment, this invention is not limited to embodiment mentioned later.

  FIG. 1 is a diagram showing a system configuration of an image forming apparatus according to the present invention. The image forming apparatus 100 includes a semiconductor device 101, ROMs (Read Only Memory) 105, 106, and 107, a memory 109, an operation unit 111, a plotter 114, and a scanner 122.

  The semiconductor device 101 is a semiconductor device such as an ASIC (Application Specific Integrated Circuit) that controls the image forming apparatus 100, and includes CPUs (Central Processing Units) 102, 103, 104, a memory controller 108, an operation unit interface 110, And an access control unit 112.

  The CPUs 102, 103, and 104 are arithmetic processing units that execute programs stored in the ROMs 105, 106, and 107. In order to simplify the description, in the present embodiment, the CPUs 102, 103, and 104 execute a network processing program, an image processing program, and an operation unit processing program that are stored in the ROMs 105, 106, and 107, respectively. In the embodiment shown in FIG. 1, three CPUs are shown. However, in the present invention, any number of CPUs can be mounted.

  The memory controller 108 is a functional unit that controls the memory 109 that is a main storage device. The memory controller 108 reads or writes data from and to the memory 109 in response to a request from other functional means.

  The operation unit interface 110 is a functional unit that controls the operation unit 111 including a display device and an operation panel (not shown). The operation unit interface 110 controls the operation unit 111 according to an operation unit process executed by the CPU 104. In the operation unit processing of the present embodiment, for example, image data stored in the external storage device 119 that is a storage unit is displayed on the display device, or image data scanned by the scanner 122 is stored in the external storage device 119.

  The access control unit 112 is a functional unit that exclusively controls access to the external storage device 119 by the CPUs 102, 103, and 104. The functional configuration of the access control unit 112 will be described in detail with reference to FIG.

  The semiconductor device 101 also includes a plotter output unit 113, a network interface 115, an output image processing unit 117, an external storage device interface 118, an input image processing unit 120, and a scanner interface 121.

  The plotter output unit 113 is a functional unit that controls the plotter 114 that draws image data on a print medium such as paper. The plotter output unit 113 controls the plotter 114 according to the plotter output process included in the image processing program executed by the CPU 103. The plotter output unit 113 outputs image data to the plotter 114 in accordance with a signal for synchronizing the drawing process by the plotter 114 (hereinafter referred to as “drawing synchronization signal”). In the present embodiment, the drawing synchronization signal can be a signal for synchronizing drawing processing of image data for one line, image data for a plurality of lines, or image data for one page.

  The network interface 115 is a functional unit that controls communication via the network 116. The network interface 115 executes various processes via the network 116 according to network processes executed by the CPU 102. In the network processing according to the present embodiment, for example, image data received via the network 116 is stored in the external storage device 119 or image data stored in the external storage device 119 is transmitted via the network 116.

  The output image processing unit 117 is a functional unit that performs image processing on the image data stored in the external storage device 119. The output image processing unit 117 performs image processing on the image data according to the output image processing included in the image processing program executed by the CPU 103. In the output image processing of the present embodiment, for example, the compressed image data in the external storage device 119 is expanded.

  The external storage device interface 118 is a functional unit that controls the external storage device 119. The external storage device 119 is various storage devices such as an HDD and a flash memory that can be connected to the image forming apparatus. The functional configuration of the external storage device interface 118 will be described in detail with reference to FIG. In the present embodiment, the external storage device 119 is not built in the image forming apparatus 100, but in another embodiment, the storage device may be built in the image forming apparatus 100.

  The input image processing unit 120 is a functional unit that performs image processing on image data to be stored in the external storage device 119. The input image processing unit 120 performs image processing on the image data according to the input image processing included in the image processing program executed by the CPU 103. In the input image processing of this embodiment, for example, image data to be stored in the external storage device 119 is compressed.

  The scanner interface 121 is a functional unit that controls the scanner 122. The scanner interface 121 controls the scanner 122 according to the scan process included in the image processing program. In the scan processing according to the present embodiment, the scanner 122 generates scan data and stores the scan data in the external storage device 119.

  FIG. 2 is a diagram showing a functional configuration of the access control unit provided in the semiconductor device of the present invention. Hereinafter, the functional configuration of the access control unit 112 will be described with reference to FIG.

  The access control unit 112 includes an interface 200, an access request holding unit 201, an allowable waiting time holding unit 202, a counter 203, an access right changing unit 204, and an access management unit 205.

  The interface 200 is an interface unit with the CPUs 102, 103, and 104. When receiving the access request, the allowable waiting time, and the transfer end notification from the CPUs 102, 103, 104, the interface 200 stores or notifies the access request holding unit 201, the allowable waiting time holding unit 202, and the access management unit 205, respectively.

  The access request is an access permission request for the external storage device 119 of the CPUs 102, 103, and 104. The transfer end notification is a notification indicating the end of data transfer of the external storage device 119 by the CPUs 102, 103, and 104.

  The waiting allowable time is the longest time that the CPU 103 that has issued the access request can allow the plotter output process to wait. In the present embodiment, the allowable waiting time is the time defined by two consecutive drawing synchronization signals and the time required to output a predetermined amount of image data from the plotter 114 (hereinafter referred to as “plotter output processing time”). .) Is the difference time. In another embodiment, the waiting allowable time can be set in consideration of the time required for data acquisition from the external storage device 119.

  The access request holding unit 201 is a functional unit that holds an access request transmitted by the CPUs 102, 103, and 104. The access request holding unit 201 stores access requests in the order in which access requests are received.

  The standby waiting time holding unit 202 is a functional unit that holds the standby waiting time transmitted by the CPU 103. When the allowable standby time holding unit 202 receives the allowable standby time from the interface 200, the standby allowable time holding unit 202 notifies the access right changing unit 204 to that effect.

  The counter 203 is a counter that counts up according to an operation clock. When the counter 203 receives a drawing synchronization signal that is a reset signal, the counter 203 clears the held counter value.

  The access right changing unit 204 is a functional unit that changes the access right for the external storage device 119 of the CPUs 102, 103, and 104. When the access right changing unit 204 receives the notification that the allowable waiting time is stored from the allowable waiting time holding unit 202, the access right changing unit 204 compares the allowable waiting time with the counter value of the counter 203, and whether the allowable standby time has elapsed. Judge whether or not. When the allowable waiting time elapses, the access right changing unit 204 instructs the access management unit 205 to permit the access to the external storage device 119 of the CPU 103 that executes the plotter output process, from another CPU. Change access rights to

  The access management unit 205 is a functional unit that manages access to the external storage device 119 by the CPUs 102, 103, and 104. When the access request is stored in the access request holding unit 201, the access management unit 205 notifies the CPU 102, 103, and 104 that transmitted the requests in the order of reception of the access requests, and notifies the external storage device 119 of the access permission. Allow access. The access permission for the CPUs 102, 103, and 104 can be notified using a register that can be referred to by these CPUs. It can also be notified by an interrupt notification.

  When the access management unit 205 is instructed by the access right changing unit 204 to permit the access of the CPU 103 that executes the plotter output process, the access management unit 205 requests a signal to stop the data transfer of the external storage device 119 by another CPU (hereinafter, referred to as the following). Asserting (validating) “transfer stop request signal”) causes the external storage device I / F 118 to stop data transfer of the external storage device 119 by another CPU.

  The access management unit 205 asserts (validates) a signal (hereinafter referred to as a “transfer stop completion signal”) for notifying completion of data transfer stop of the external storage device 119 by another CPU. It detects that the data transfer by the CPU has stopped. When the data transfer by the other CPU is stopped, the access management unit 205 notifies the CPU 103 that executes the plotter output process of access permission to the external storage device 119 and causes the plotter output process to be executed.

  Upon receiving a transfer end notification from the CPU 103, the access management unit 205 asserts a signal (hereinafter referred to as a “transfer restart request signal”) requesting resumption of data transfer of the external storage device 119 by another stopped CPU. As a result, the external storage device I / F 118 restarts the data transfer.

  FIG. 3 is a diagram showing a functional configuration of the external storage device I / F provided in the semiconductor device of the present invention. The functional configuration of the external storage device I / F 118 will be described below with reference to FIG.

  The external storage device I / F 118 includes a memory interface control unit 300, an operation setting holding unit 301, an operation setting saving unit 302, an operation change management unit 303, a transfer control unit 304, an interrupt control unit 305, an external storage A device interface control unit 306.

  The memory interface control unit 300 is an interface unit with the memory 109 and performs data transfer with the memory 109 in accordance with an instruction from the transfer control unit 304.

  The operation setting holding unit 301 holds transfer control parameters that the CPUs 102, 103, and 104 transmit together with data transfer requests (data write requests and read requests). The transfer control parameter is a parameter that controls data transfer of the external storage device 119. The transfer control parameter includes at least information such as an instruction for instructing data writing or reading, a start address for specifying a data writing or data reading position, and an offset from the end address or start address (that is, a transfer data size). The operation setting holding unit 301 holds only one transfer control parameter.

  Further, the operation setting holding unit 301 saves the transfer control parameter and the stop state information regarding the data transfer being executed in the operation setting saving unit 302 serving as a storage unit according to an instruction from the operation change management unit 303. In this embodiment, when the transfer setting parameter is saved, the operation setting holding unit 301 deletes the transfer control parameter saved in the operation setting holding unit 301.

  The stop state information is information indicating the state of data transfer when the data transfer of the external storage device 119 is stopped. For example, when data writing to the external storage device 119 is stopped, the stop state information includes the memory address of the external storage device 119 to which data was last written, and the data acquired last from the memory 109. This is information indicating the address of the memory 109. When data reading from the external storage device 119 is stopped, the stop state information is information indicating the address of the external storage device 119 where the data acquired last from the external storage device 119 is stored.

  The operation change management unit 303 is a functional unit that controls stop and restart of data transfer between the external storage device 119 and the memory 109. When the operation change management unit 303 detects a data transfer stop request from the access control unit 112, the operation change management unit 303 requests the transfer control unit 304 to stop data transfer. In addition, the operation change management unit 303 causes the operation setting storage unit 301 to store, in the operation setting saving unit 302, transfer control parameters and stop state information regarding data transfer being executed. When the data transfer is stopped and the transfer control parameter and the stop state information are saved, the operation change management unit 303 notifies the access control unit 112 that the data transfer has been stopped by asserting a transfer stop completion signal. To do.

  When the operation change management unit 303 detects a data transfer restart request from the access control unit 112, the operation change management unit 303 causes the operation setting holding unit 301 to acquire the transfer control parameters and stop state information saved in the operation setting saving unit 302, and The transfer control unit 304 is caused to resume data transfer according to the transfer control parameter and the stop state information. In addition, the operation change management unit 303 instructs the interrupt control unit 305 to prohibit the interrupt to the CPU that has been executing the process for which the data transfer is stopped.

  The transfer control unit 304 is a functional unit that controls data transfer between the external storage device 119 and the memory 109. The transfer control unit 304 controls data transfer of the external storage device 119 via the memory interface control unit 300 and the external storage device interface control unit 306 based on the transfer control parameter held in the operation setting holding unit 301.

  When the transfer control parameter is stored in the operation setting holding unit 301, the transfer control unit 304 starts data transfer according to the transfer control parameter. When the transfer control unit 304 receives a data transfer stop instruction from the operation change management unit 303, the transfer control unit 304 immediately stops the data transfer. For this reason, in the present invention, the access right can be quickly transferred.

  When the stop state information is stored in the operation setting holding unit 301 together with the transfer control parameter, the transfer control unit 304 resumes the stopped data transfer according to the transfer control parameter and the stop state information. In an embodiment in which the transfer control unit 304 holds data to be transferred in a predetermined data unit and writes data to the external storage device 119, if data transfer is stopped during data writing to the external storage device 119, The data held by the control unit 304 is lost. Therefore, the transfer control unit 304 refers to the stop state information, calculates the address of the memory 109 in which the data held by the transfer control unit 304 when the data transfer is stopped, and stores the data in the memory 109 again. Then, the transfer control unit 304 resumes the stopped data transfer by writing the data to the external storage device 119. Thus, in the present invention, even if the data transfer is stopped immediately after receiving the data transfer stop instruction, data loss can be prevented.

  The interrupt control unit 305 is a functional unit that generates an interrupt related to data transfer to the external storage device 119. The interrupt control unit 305 generates an interrupt such as a data transfer completion interrupt that is generated when the data transfer to the external storage device 119 is completed and an error interrupt that is generated when an error occurs in the data transfer to the external storage device 119. Generated and notified to the CPUs 102, 103, and 104. However, the interrupt control unit 305 does not generate an interrupt to the CPU designated by the operation change management unit 303.

  The external storage device interface control unit 306 is an interface unit with the external storage device 119 and performs data transfer with the external storage device 119 in accordance with instructions from the transfer control unit 304.

  FIG. 4 is a sequence diagram showing access control processing executed by the image forming apparatus of the present invention. In the following, referring to FIG. 4, when CPU 102 that executes network processing is writing data to external storage device 119, CPU 103 that executes plotter output processing grants access permission to external storage device 119. The access control process when requested is described.

  The CPU 102 transmits an access request for the external storage device 119 to the access control unit 112 (step S400). In the present embodiment, when the access control unit 112 has not received an access request from another CPU, the access control unit 112 notifies the CPU 102 of access permission (step S401). When notified of access permission, the CPU 102 transmits a transfer control parameter to the external storage device interface 118 to instruct data transfer (data write) (step S402). The external storage device interface 118 is activated when a transfer control parameter is received from the CPU 102, and transfers and writes data specified by the CPU 102 from the memory 109 to the external storage device 119 in accordance with the transfer control parameter (step S403).

  The CPU 103 transmits an access request for the external storage device 119 to the access control unit 112 (step S404). When receiving an access request from the CPU 103, the access control unit 112 determines whether or not the allowable waiting time received with the access request has elapsed (step S405). When the allowable waiting time designated by the CPU 103 has elapsed, the access control unit 112 asserts a transfer stop request signal (step S406).

  When the transfer stop request signal is asserted, the external storage device interface 118 stops data transfer by the CPU 102 being executed (step S407), and saves the transfer control parameter and the stop state information (step S408). Next, the external storage device interface 118 asserts a transfer stop completion signal (step S409).

  When the transfer stop completion signal is asserted, the access control unit 112 negates (invalidates) the transfer stop request signal (step S410), and notifies the CPU 103 of access permission (step S411).

  When the access permission is notified, the CPU 103 transmits a transfer control parameter to the external storage device interface 118 to instruct data transfer (reading) (step S412). The external storage device interface 118 is activated upon receiving a transfer control parameter from the CPU 103, reads image data to be transferred from the external storage device 119 in accordance with the transfer control parameter (step S413), and transfers it to the memory 109 (step S414). .

  The CPU 103 causes the image data transferred from the external storage device 119 to be output from the memory 109 to the plotter output unit 113 (step S415). When receiving the image data from the memory 109, the plotter output unit 113 outputs the image data to the plotter 114 (step S416), and the plotter 114 prints the image data on the print medium (step S417).

  When the CPU 103 outputs the image data to the plotter output unit 113, the CPU 103 transmits a transfer end notification to the access control unit 112 (step S418). When receiving the transfer end notification, the access control unit 112 asserts a transfer resumption request signal (step S419). When the transfer restart request signal is asserted, the external storage device interface 118 restarts the stopped data transfer according to the saved transfer control parameter and the stop state information (step S420).

  FIG. 5 is a flowchart showing processing executed by the access control unit provided in the semiconductor device of the present invention. Hereinafter, processing executed when the access control unit 112 receives an access request from the CPU 103 that should execute the plotter output processing will be described with reference to FIG.

  The process of FIG. 5 starts from step S500 when the interface 200 of the access control unit 112 receives an access request and an allowable waiting time from the CPU 103. In step S <b> 501, the interface 200 saves the access request in the access request holding unit 201 and saves the allowable waiting time in the allowable waiting time holding unit 202.

  In step S502, the access right changing unit 204 determines whether or not the permissible waiting time has elapsed. If the waiting allowable time has not elapsed (no), the process of step S502 is repeated. On the other hand, if the waiting allowable time has elapsed (yes), the process branches to step S503.

  In step S503, the access right changing unit 204 causes the access management unit 205 to assert a transfer stop request signal and instructs the external storage device interface 118 to stop data transfer. In step S504, the access management unit 205 determines whether the transfer stop completion signal is asserted. If the transfer stop completion signal is not asserted (no), the process of step S504 is repeated. On the other hand, if the transfer stop completion signal is asserted (yes), that is, if the external storage device interface 118 has completed the stop of data transfer by another CPU, the process branches to step S505.

  In step S505, the access management unit 205 negates a transfer stop request signal. In step S506, the access management unit 205 notifies the access permission to the CPU 103 that should execute the plotter output process.

  In step S507, the access management unit 205 determines whether a transfer end notification has been received from the CPU 103. If the transfer end notification has not been received (no), the process of step S507 is repeated. On the other hand, if the transfer end notification is received (yes), the process branches to step S508. In step S508, the access management unit 205 asserts the transfer restart request signal to instruct the external storage device interface 118 to restart data transfer, and the process ends in step S509.

  FIG. 6 is a flowchart showing processing executed by the external storage device interface provided in the semiconductor device of the present invention. Hereinafter, with reference to FIG. 6, a description will be given of processing executed when the external storage device interface 118 is instructed to stop data transfer from the access control unit 112.

  The processing in FIG. 6 starts from step S600 when the operation change management unit 303 of the external storage device interface 118 detects that the transfer stop request signal is asserted. In step S601, the operation change management unit 303 instructs the transfer control unit 304 to stop data transfer, and the transfer control unit 304 stops the data transfer being executed.

  In step S602, the operation change management unit 303 instructs the operation setting holding unit 301 to save the transfer control parameter and the stop state information, and the operation setting holding unit 301 generates stop state information and sets the operation setting together with the transfer control parameter. Retreat to the retreat unit 302.

  In step S <b> 603, the transfer control unit 304 determines whether the data transfer is instructed by determining whether the transfer control parameter is stored in the operation setting holding unit 301. If data transfer is not instructed (no), the process of step S603 is repeated. On the other hand, if data transfer is instructed (yes), the process branches to step S604.

  In step S <b> 604, the transfer control unit 304 reads image data from the external storage device 119 via the external storage device interface control unit 306 according to the transfer control parameters stored in the operation setting holding unit 301. In step S <b> 605, the transfer control unit 304 transfers the image data to the memory 109 via the memory interface control unit 300.

  In step S606, the operation change management unit 303 determines whether or not the transfer resumption request signal is asserted. If the transfer resumption request signal is not asserted (no), the process of step S606 is repeated. On the other hand, if the transfer restart request signal is asserted (yes), the process branches to step S607.

  In step S607, the operation change management unit 303 causes the operation setting holding unit 301 to store the transfer control parameters and stop state information saved in the operation setting saving unit 302. When the transfer control parameter and the stop state information are stored in the operation setting saving unit 302, the transfer control unit 304 resumes the stopped data transfer in step S608, and the process ends in step S609.

  FIG. 7 is a diagram showing the relationship between the state of processing executed by the image forming apparatus of the present invention and signals and notifications processed by the image forming apparatus. Hereinafter, with reference to FIG. 7, the relationship between the network processing, the operation unit processing, and the plotter output processing and the transfer stop request signal, transfer stop completion signal, transfer restart request signal, access permission notification, and transfer end notification will be described.

  The counter 203 included in the access control unit 112 counts up (“0” to “n”) according to the operation clock, and is reset by a counter reset signal that is a drawing synchronization signal of the plotter 114. As described above, the allowable waiting time is a difference time between the time from when the counter 203 is reset to the next reset and the plotter output processing time, and an arbitrary value (m) that the counter 203 can take is used. Can be expressed.

  In the embodiment shown in FIG. 7, it is assumed that network processing, operation unit processing, and plotter output processing sequentially request access permission of the external storage device 119. First, an access right is granted to the CPU 102 that transmitted the access request earliest, and network processing is executed. When the network process ends, an access right is granted to the CPU 104 that has transmitted the access request second, and the operation unit process is executed.

  On the other hand, the access control unit 112 determines whether the allowable waiting time has elapsed due to an access request by the CPU 103 that should execute the plotter output process, and the value of the counter 203 is the same as the value (m) indicating the allowable waiting time. Then, the transfer stop request signal is asserted. When the external storage device interface 118 detects the assertion of the transfer stop request signal, the external storage device interface 118 stops the data transfer accompanying the operation processing by the CPU 104 and asserts the transfer stop completion signal.

  When the access control unit 112 detects the assertion of the transfer stop completion signal, the access control unit 112 grants the access right to the CPU 103, and the plotter output process by the CPU 103 is executed. When the plotter output process ends, the CPU 103 transmits a transfer end notification to the access control unit 112. When receiving the transfer end notification, the access control unit 112 asserts a transfer resumption request signal. When the external storage device interface 118 detects the assertion of the transfer resumption request signal, the external storage device interface 118 resumes the operation unit processing by the CPU 104 that has been stopped.

  In the present invention, the CPU executing the stopped process is not notified of the change of the access right or the stop of the data transfer, and the restart of the data transfer is not requested. The access control method of the present invention can be introduced without modification.

  In the above-described embodiment, the plotter output processing by the CPU 103 transmits a transfer end notification to the access control unit 112. However, in other embodiments, the external storage device interface 118 has completed data transfer accompanying the plotter output processing by the CPU 103. This may be detected, and the operation unit processing by the CPU 104 that has been stopped may be resumed.

  Although the present embodiment has been described so far, the present invention is not limited to the above-described embodiment, and the constituent elements of the present embodiment are changed or deleted, or the constituent elements of the present embodiment are changed to other configurations. Changes can be made within the range that can be conceived by those skilled in the art, such as adding elements. Moreover, as long as the effect of this invention is show | played in any aspect, it is contained in the range of this invention.

DESCRIPTION OF SYMBOLS 100 ... Image forming apparatus, 101 ... Semiconductor device, 102, 103, 104 ... CPU, 105, 106, 107 ... ROM, 108 ... Memory controller, 109 ... Memory, 110 ... Operation part interface, 111 ... Operation part, 112 ... Access Control unit 113... Plotter output unit 114... Plotter 115... Network interface 116 116 network 117 output image processing unit 118 external storage device interface 119 external storage unit 120 input image processing unit 121 ... Scanner interface, 122 ... Scanner

JP 2010-140290 A

Claims (9)

A plurality of arithmetic processing means accessible to the external storage device;
An access control means for exclusively controlling access to the external storage device by the plurality of arithmetic processing means,
The access control means includes
When there is an access request from an arithmetic processing means for executing output processing for outputting data stored in the external storage device, it is determined whether a predetermined standby time has elapsed, and when the standby time has elapsed, A semiconductor device, wherein an operation processing means for executing an output process is allowed to access the external storage device. The access control means includes
2. The semiconductor device according to claim 1, wherein when permitting an arithmetic processing unit that executes the output processing to access the external storage device, data transfer of the external storage device by another arithmetic processing unit is stopped. The access control means includes
3. The semiconductor device according to claim 2, wherein when the output processing is completed, data transfer of the external storage device by the other arithmetic processing unit is resumed. A plurality of arithmetic processing means accessible to an external storage device connectable to the image forming apparatus;
An image forming apparatus comprising a semiconductor device comprising: an access control unit that exclusively controls access to the external storage device;
The access control means includes
When there is an access request from an arithmetic processing means for executing output processing for outputting data stored in the external storage device, it is determined whether a predetermined standby time has elapsed, and when the standby time has elapsed, An image forming apparatus, wherein an operation processing unit that executes output processing is allowed to access the external storage device. The access control means includes
The image forming apparatus according to claim 4, wherein when the arithmetic processing unit that executes the output process is allowed to access the external storage device, data transfer of the external storage device by another arithmetic processing unit is stopped. The access control means includes
The image forming apparatus according to claim 5, wherein when the output process ends, the data transfer of the external storage device by the other arithmetic processing unit is resumed. An access control method executed by a semiconductor device accessible to an external storage device, the access control method comprising:
Determining whether a predetermined standby time has elapsed when there is an access request from an arithmetic processing means for executing output processing for outputting data stored in the external storage device;
An access control method, comprising: permitting an arithmetic processing unit that executes the output process to access the external storage device when the standby time has elapsed. Granting the access comprises:
The access according to claim 7, further comprising: stopping data transfer of the external storage device by another arithmetic processing unit when permitting the arithmetic processing unit that executes the output processing to access the external storage device. Control method. In the access control method, the semiconductor device includes:
The access control method according to claim 8, further comprising a step of resuming data transfer of the external storage device by the other arithmetic processing unit when the output process ends.