JP2013098643A - Data transfer control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data transfer control device capable of preventing data transfer stop and abnormal heat generation in a circuit which are caused by continuous and high-speed data transfer.SOLUTION: A data transfer control device (20) includes: a host interface part (24) which can exchange data with a host device; a peripheral device interface part (21) which can exchange data with a peripheral device; an abnormality detection part (25) which detects an abnormal state in the host interface part or the peripheral device interface part; and a transfer control part (25), when the abnormality detection part detects an abnormality, stops data transfer in the host interface part or the peripheral device interface part, and then, when the abnormality detection part detects recovery of the host interface part or the peripheral device interface part to the normal status, resumes data transfer operation in the host interface part or the peripheral device interface part.

Description

  The present invention relates to a data transfer control device that controls data transfer between a peripheral device and a host device.

  When displaying the image captured by the camera sensor as a moving image on a screen such as a display on the host device, the camera sensor captures an image with a specified image size and frame rate (number of still images transferred per second). . The captured image data is transferred to the host device via the image capturing device. When image data is transmitted without error to the host device via the image pickup device, the screen on the host device is updated. By continuing this series of operations, it is possible to display a moving image (see, for example, Patent Document 1).

  The host interface unit of such an image pickup apparatus often uses an isochronous transfer method with a general-purpose interface such as USB (Universal Serial Bus) or PCI-Express.

  The isochronous transfer method when transfer is performed in units of packets in a USB or the like is a transfer method that emphasizes real-time properties for ensuring a certain amount of data such as voice and moving images within a certain time. In the case of USB 2.0 high-speed mode, a data transfer request packet is sent from the host device based on the SOF (start of frame) packet transferred every microframe with a 125 microsecond interval as a microframe. In response to this, data is transferred by a data transfer packet. When there is no data that can be transferred at the time of data request, a packet with a data amount of zero is transferred (zero-length response), and data transfer is not performed during the microframe period.

  At the time of zero-length packet, since there is no data, it is discarded by the host device. Therefore, in the case of an image pickup device in which two transfer data packets via the USB interface are set as one still image, transfer data other than the zero-length packet are added together to form one still image. The screen on the host device is updated. By continuing this operation, a moving image can be displayed.

  In recent years, the amount of data to be transferred tends to increase with an increase in the size of an image to be captured, and a high-speed interface that uses differential signals is required in the camera sensor interface unit and the host interface unit. In addition, with the progress of semiconductor circuit element miniaturization technology, the amount of current and the amount of heat generated per unit area increase, and the amount of heat dissipation tends to decrease.

  Since the high-speed interface is a high-speed operation clock of several hundred MHz to several GHz, the amount of current consumption and the amount of heat generation are remarkably increased. When data transfer is continuously executed with such a high-speed interface and the state in which the circuit operation activity rate is high is maintained, the circuit portion locally overheats, and the circuit element cannot maintain normal characteristics, Data cannot be transferred normally.

  In particular, in the case of an image pickup circuit that handles moving images, there are problems that the moving image of the picked-up image stops due to abnormal data transfer, and that the data transfer circuit generates abnormal heat.

  The present invention provides a data transfer control device that transfers data between a peripheral device and a host device, and is capable of avoiding data transfer stop and abnormal circuit heat generation caused by continuous and high-speed data transfer. An object is to realize a transfer control device.

  A data transfer control device according to the present invention is a data transfer control device that performs data transfer between a peripheral device and a host device, a host interface unit capable of exchanging data with the host device, and a peripheral device Peripheral device interface unit that can exchange data with the device, an abnormality detection unit that detects an abnormal state of the host interface unit or the peripheral device interface unit, and a host interface unit when the abnormality detection unit detects an abnormality Or, if the data transfer at the peripheral device interface unit is interrupted, and then the abnormality detection unit detects the recovery of the host interface unit or the peripheral device interface unit to the normal state, the data at the host interface unit or the peripheral device interface unit Transfer control unit that resumes transfer operation Equipped with a.

  An image capturing apparatus according to the present invention is an image capturing apparatus capable of transferring image data captured by a camera sensor to a host apparatus, and a host interface unit capable of exchanging data with the host apparatus. , A camera sensor interface unit capable of exchanging data with the camera sensor, an abnormality detection unit for detecting an abnormal state of the host interface unit or the camera sensor interface unit, and an abnormality detection unit detecting an abnormality When the host interface unit or the camera sensor interface unit interrupts data transfer, and then the abnormality detection unit detects the recovery of the host interface unit or camera sensor interface unit to a normal state, the host interface unit or camera sensor In the interface part It resumes data transfer operation and a transfer control unit.

  According to the present invention, when an abnormal state is detected, the data transfer is interrupted, and then the data transfer is resumed when the abnormal state disappears. As a result, abnormal stop of data transfer and abnormal heat generation of the circuit due to continuous and high-speed data transfer can be avoided.

1 is a block diagram illustrating a configuration of an image capturing apparatus according to a first embodiment. Timing chart explaining the isochronous transfer method FIG. 3 is a block diagram illustrating a configuration of an image capturing apparatus according to a second embodiment. 7 is a flowchart illustrating the operation of the image capturing apparatus according to the second embodiment. Timing chart showing operation of image pickup apparatus of embodiment 2 FIG. 4 is a block diagram illustrating a configuration of an image capturing apparatus according to a third embodiment. 7 is a flowchart illustrating the operation of the image capturing apparatus according to the third embodiment. Timing chart showing operation of the image pickup apparatus of Embodiment 3 FIG. 6 is a block diagram illustrating a configuration of an image capturing apparatus according to a fourth embodiment. 9 is a flowchart showing the operation of the image capturing apparatus according to the fourth embodiment. Timing chart showing operation of image pickup apparatus of embodiment 4 The block diagram which shows the structure of the card reader / writer which is other embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

1. Embodiment 1
1-1. Outline An image capturing apparatus (data transfer control apparatus) described below stops data transfer from an image capturing apparatus to a host apparatus when the abnormality detecting section detects an abnormal state of the host interface section. The image capturing apparatus waits as it is until the host interface unit can operate normally. When the host interface unit can operate normally, the image capturing apparatus resumes data transfer to the host apparatus.

  As described above, the image pickup apparatus can avoid an unintended data transfer error by detecting an abnormal state of the host interface unit.

1-2. Configuration An image pickup apparatus according to a first embodiment of the present invention will be described. FIG. 1 is a block diagram illustrating an image capturing apparatus according to the first embodiment.

  The image capturing device 20 is connected to the host device 10 and the camera sensor 30.

  The image capturing apparatus 20 includes a camera sensor interface unit 21, a camera sensor control unit 22, an image processing unit 23, a host interface unit 24, and an abnormality detection unit 25.

  The camera sensor interface unit 21 controls data communication between the camera sensor 30 that captures an image and the image capturing apparatus 20. The camera sensor control unit 22 controls imaging conditions such as the size and frame rate of an image captured by the camera sensor 30. The image processing unit 23 performs processing such as color tone correction and compression of image data input from the camera sensor interface unit 21.

  The host interface circuit 24 controls data communication between the host device 10 and the image capturing device 20.

  The host device 10 requests and receives image data from the image capturing device 20 in order to realize the designated moving image frame rate. If there is no error in the image data for one sheet, the host device 10 renders the image data on the screen on the host device 10 and repeats this to realize moving image display. If there is an error in the image data for one sheet, the image data is discarded and the screen on the host device 10 is not updated. Also, the screen on the host device 10 is not updated when image data is not transferred from the image capturing device 20.

  The abnormality detection unit 25 has an abnormality detection function for detecting an abnormal state of the host interface unit 24 and a transfer control function for controlling data transfer according to the abnormal state of the host interface unit 24. The abnormality detection unit 25 monitors the state of the host interface unit 24, and stops the output of the image processing unit 23 when detecting the abnormal state. When the host interface unit 24 enters an abnormal state, an error is likely to occur in data transfer to the host device 10.

  In the present embodiment, data transfer between the image capturing device 20 and the host device 10 is performed by an isochronous transfer method.

  The isochronous transfer method will be described with reference to FIG. The isochronous transfer method when transfer is performed in units of packets in an interface such as a USB is a transfer method that emphasizes real-time properties for ensuring a certain amount of data such as voice and moving images within a certain time.

  For example, in the case of the USB 2.0 high-speed mode, as shown in FIG. An SOF (start of frame) packet transmitted from the host device for each microframe is a reference. Thereafter, a data transfer request packet is transmitted from the host device 10 at the timing shown in FIG. In response to this, data is transferred as a data transfer packet from the image capturing device 20 to the host device 10 at the timing shown in FIG.

  If there is no data that can be transferred when the host device 10 requests data, the image capturing device 20 transfers a packet with a data amount of zero, and no data is transferred during the microframe period. This is called “zero-length response”.

  The SOF packet, the data transfer request packet, and the data transfer packet as described above are performed on the same transmission line. FIG. 2D shows the active state of this transmission line (USB interface). The active state is a state where a packet is flowing.

  In the example of FIG. 2, in the second microframe, a packet with a data amount of zero is transferred with respect to the data transfer request packet (zero-length response).

  When the transfer data for the USB interface twice corresponds to one still image, in the example of FIG. 2, since the zero-length response is made in the second transfer, the host device performs the first and second transfers. The third transfer data is added to form one still image, and the screen on the host device 10 is updated using this. By continuing this operation, a moving image can be displayed.

The camera sensor 30 in FIG. 1 may be an image sensor that uses a general CMOS.
Moreover, not only a CMOS sensor but an image sensor such as a CCD may be used.

1-3. Operation In the present embodiment, when detecting an abnormality in the host interface unit 24, the image capturing apparatus 20 stops data transfer to the host apparatus 10 and waits for a predetermined time. Thereafter, when the image capturing apparatus 20 determines that the state of the host interface unit 24 is normal, the data transfer to the host apparatus 10 is resumed. Details of this operation will be described below.

  When the image capturing apparatus 20 receives an image capturing start command from the host computer 10, settings such as the specified image size and frame rate are transmitted to the camera sensor 30 via the camera sensor control unit 22 and the camera sensor interface unit 21. Then, the camera sensor 30 starts imaging and transmitting image data to the image capturing apparatus 20. The image data input from the camera sensor 30 to the image capturing apparatus 20 is subjected to processing such as color tone correction and compression by the image processing unit 23.

  The abnormality detection unit 25 monitors the state of the host interface unit 24.

  While the state of the host interface unit 24 is normal, the image data processed by the image processing unit 23 is transferred from the host interface unit 24 to the host device 10. Unless the host device 10 requests completion of imaging, the image imaging device 20 repeats the above image processing and data transfer. This realizes moving image data transfer to the host device 10.

  On the other hand, when the abnormality detection unit 25 detects an abnormality in the host interface unit 24, the abnormality detection unit 25 stops the operation of the image processing unit 23. Further, the abnormality detection unit 25 stops the operation of the host interface unit 24. Thereby, the image data transfer from the image capturing device 20 to the host device 10 is interrupted.

  The image capturing device 20 stops transferring image data to the host device 10 until the abnormality detection unit 25 determines that the state of the host interface unit 24 has returned to normal. During this time, since data is not sent from the image processing unit 23 to the host interface unit 24, data transfer from the image capturing device 20 to the host device 10 is a zero-length response.

  When the abnormality detection unit 25 determines that the state of the host interface unit 24 has returned to normal, the abnormality detection unit 25 resumes the operation of the image processing unit 23.

  The determination of abnormality / normality in the above may be determined for each frame of image data or for each data packet.

  In addition, when the host device 10 requests the end of shooting while the image pickup device 20 stops data transfer, the image pickup may be ended.

1-4. Summary of the present embodiment In the present embodiment, the image capturing apparatus 20 stops data transfer from the image capturing apparatus 20 to the host apparatus 10 when the abnormality detecting section 25 detects an abnormal state of the host interface section 24. The image capturing apparatus 20 interrupts the transfer of the image data until the host interface unit 24 is in a state where it can operate normally. When the host interface unit 24 is in a state where it can operate normally, the image capturing apparatus 20 resumes data transfer to the host apparatus 10.

  As described above, the image capturing apparatus 20 can detect abnormal stop of the data transfer and abnormal heat generation of the circuit due to continuous and high-speed data transfer by detecting the abnormal state of the host interface unit 24. it can.

2. Embodiment 2
In the present embodiment, a more specific example of the image pickup apparatus shown in the first embodiment is shown. Here, an example will be described in which a USB is used as an interface between a host computer (host device) and an image capturing device, a CMOS sensor is used as a camera sensor, and an abnormal state of the interface is determined based on the interface temperature.

2-1. Configuration The configuration of the image capturing apparatus of the present embodiment will be described. FIG. 3 is a block diagram showing a configuration of the image pickup apparatus of the present embodiment.

  The image capturing apparatus 20b according to the second embodiment is connected to the host computer 10b and the CMOS sensor 30b. The image capturing device 20b is connected to the host computer 10b by USB connection.

  Each block included in the image capturing device 20b is a more specific example of each block included in the image capturing device 20 of the first embodiment.

  In the second embodiment, the abnormality detection unit 25b corresponds to the abnormality detection unit 25 of the first embodiment. The abnormality detection unit 25b includes a USB interface temperature detection circuit 26b and a clock generation circuit 27b. The USB interface temperature detection circuit 26b has an abnormality detection function for detecting an abnormal state of the USB interface circuit 24b, and the clock generation circuit 27b has a transfer control function for controlling data transfer according to the abnormal state of the USB interface circuit 24b. ing.

  The USB interface temperature detection circuit 26b monitors the temperature of the USB interface circuit 24b. The USB interface temperature detection circuit 26b compares the temperature of the USB interface circuit 24b with a preset threshold value and sends a clock stop signal or a clock permission signal to the clock generation circuit 27b. The threshold value set here may be changeable by an internal register or the like.

  The clock generation circuit 27b generates a clock necessary for the operation of each block of the image pickup device 20b, and supplies the clock to the image processing circuit 23b according to the clock stop signal / permission signal from the USB interface temperature detection circuit 26b. Switch.

  The state of the image pickup device 20b from when the clock stop signal is output from the USB interface temperature detection circuit 26b to when the clock permission signal is output is referred to as “heat dissipation mode”. Other states where imaging and data transfer are performed are referred to as “normal mode”.

  The data transfer between the USB interface circuit 24b and the host computer 10b uses the isochronous transfer method as in the first embodiment.

  If the USB bus activation rate is high for a long time in isochronous transfer, the temperature of the interface circuit rises. In particular, the USB interface circuit 24b is locally overheated.

  If the USB interface circuit 24b is overheated, an error is likely to occur in data transfer from the USB interface circuit 24b to the host computer 10b.

  The CMOS sensor 30b may be an image sensor using a general CMOS.

2-2. Operation The operation of this embodiment will be described with reference to FIGS. FIG. 4 shows a flowchart of the image capturing and transferring process according to the second embodiment of the present invention.

  When the image capturing device 20b receives an image capturing start command from the host computer 10b, the image capturing device 20b transmits settings such as the designated image size and frame rate to the CMOS sensor 30b via the CMOS sensor control circuit 22b and the CMOS sensor interface circuit 21b. To do. Then, the CMOS sensor 30b starts image capturing and image data transmission to the image capturing device 20b (S102). When the transfer of the image data is started, the image data input from the CMOS sensor 30b to the image pickup device 20b is subjected to processing such as color correction and compression in the image processing circuit 23b (S103).

  Thereafter, the USB interface temperature detection circuit 26b detects the temperature of the USB interface circuit 24b, and compares the detected temperature with a preset threshold value 1 (S104).

  At this time, if the temperature of the USB interface circuit 24b is lower than the threshold value 1, the image processing circuit 23b transfers the processed image data to the host computer 10b via the USB interface circuit 24b (S105).

  The image capturing apparatus 20b repeats the image processing (S103) and the transfer process (S105) until receiving a request for the end of imaging from the host computer 10b, thereby realizing moving image data transfer to the host computer 10b.

  On the other hand, when the temperature of the USB interface circuit 24b is equal to or higher than the threshold value 1 in step S104, the image capturing device 20b shifts to the heat dissipation mode (S111).

  In the heat dissipation mode, when the USB interface temperature detection circuit 26b transmits a clock stop signal to the clock generation circuit 27b, the clock generation circuit 27b stops the clock to the image processing circuit 23b (S112). When the clock is stopped, data transfer from the USB interface circuit 24b to the host computer 10b is stopped, so that heat generation in the USB interface circuit 24b is suppressed and the temperature of the USB interface circuit 24b decreases.

  Thereafter, the USB interface temperature detection circuit 26b detects the temperature of the USB interface circuit 24b. While the temperature is greater than the preset threshold 2, the clock generation circuit 27b continues to stop the clock to the image processing circuit 23b (S113). When the temperature of the USB interface circuit 24b becomes equal to or lower than the threshold value 2, the USB interface temperature detection circuit 26b transmits a clock permission signal to the clock generation circuit 27b. Then, the clock generation circuit 27b resumes clock transmission to the image processing circuit 23b (S114). Then, the image capturing apparatus 20b shifts to the normal mode and resumes image processing and transfer processing (S115).

  The temperature abnormality determination in steps S104 and S113 may be determined for each frame of the image data or for each USB packet.

  Further, when the host computer 10b requests the end of imaging in the heat dissipation mode, the imaging may be ended.

  Next, the operation of the image pickup device 20b will be described in accordance with the temperature change of the USB interface circuit 24b. FIG. 5 is a timing chart at the time of image transfer processing of the image capturing apparatus 20b of the present embodiment.

  5A to 5E, the horizontal axis indicates the passage of time. The vertical axis in FIG. 5A indicates the temperature of the USB interface circuit 24b. FIG. 5B shows data transferred from the CMOS sensor 30b to the image capturing device 20b. Each of A to X represents data for one image. FIG. 5C shows data transferred from the image capturing apparatus 20b to the host computer 10b. Each of a to x represents data for one image. The vertical axis in FIG. 5D indicates the USB bus activation rate. The activation rate is the ratio of the time during which the USB bus is active to the time of the microframe. In the case of USB 2.0 high-speed mode isochronous transfer, the maximum bus activation rate in each microframe is about 41%, and in the case of zero-length response, it is about 1%. FIG. 5E shows a clock signal transmitted from the clock generation circuit 27b to the image processing circuit 23b.

  Imaging of the subject is started, and processing of the image data A input from the CMOS sensor 30b is started (FIG. 5B, timing T1). Then, the image processing circuit 23b processes the image data A input from the CMOS sensor 30b, and the transfer of the data a to the host computer 10b is started via the USB interface circuit 24b (FIG. 2 (c), timing T2 ).

  Note that there is a time lag (T2-T1) from when the data A is transmitted from the CMOS sensor 30c to when the data a is transmitted to the host computer 10c. Further, as shown in FIG. 8D, until the data a is transmitted from the image capturing apparatus 20c to the host computer 10c, zero-length data is transmitted, but the amount of data transferred is completely zero. Don't be. Therefore, the USB bus activation rate does not become zero.

  Thereafter, by repeating the image processing and the transfer processing, the state where the USB bus activation rate is high is maintained, so that the temperature of the USB interface circuit 24b rises (FIG. 5A, timing T3).

  When the temperature of the USB interface circuit 24b becomes equal to or higher than the threshold value 1, the USB interface temperature detection circuit 26b issues a heat dissipation mode shift command, and causes the clock generation circuit 27b to stop clock transmission to the image processing circuit 23b (FIG. 5 (e), Timing T4). The period during which the clock is stopped is indicated by C in FIG.

  In the heat dissipation mode, image data from the CMOS sensor 30b continues to be input, but no data is input to the USB interface circuit 24b because the operation of the image processing circuit 23b is stopped. Therefore, the image capturing apparatus 20b always makes a zero-length response to a data request from the host computer 10b (FIG. 5 (d), timing T5). In FIG. 5D, t1 indicates a period during which a zero-length response is performed.

  Further, since the data m to the host computer 10b is not completely transmitted, the display on the host computer 10b remains displaying the image data 1 that has finally sent all the data.

  Since the image data transfer to the host computer 10b is stopped during the heat dissipation mode, the state where the USB bus activation rate is low is maintained. As a result, the heat generation of the USB interface circuit 24b is suppressed, and the temperature of the USB interface circuit 24b is lowered (FIG. 5A, timing T5).

  When the temperature of the USB interface circuit 24b becomes equal to or lower than the threshold value 2, the USB interface temperature detection circuit 26b issues a normal mode transition command, and causes the clock generation circuit 27b to resume clock transmission to the image processing circuit 23b (FIG. 5 (e), Timing T6). As a result, the image capturing apparatus 20b resumes image processing and data transfer (FIG. 5 (d), timing T6).

  Here, there is a time lag in the increase of the USB bus activation rate after shifting to the normal mode. This is because there is a time lag between the transition to the normal mode and the restart of clock transmission to the image processing circuit 23b until the actual transfer of data to the host computer.

  When the data transfer is resumed, the USB bus activation rate is increased again, and accordingly, the temperature of the USB interface circuit 24b is increased again. Thereafter, similarly, the image capturing apparatus 20b repeats the normal mode and the heat dissipation mode.

2-4. Summary of the present embodiment When the USB interface temperature detection circuit 26b detects abnormal heat generation of the USB interface circuit 24b due to continuous and high-speed data transfer, the data transfer from the image pickup device 20b to the host computer 10b is stopped. Since heat generation is suppressed by stopping the data transfer, the temperature can be lowered. When the temperature is such that the USB interface circuit 24b can operate normally, the image capturing device 20b resumes data transfer to the computer 10b.

  As described above, the image capturing apparatus 20b detects and copes with abnormal heat generation of the host interface circuit 24b, thereby avoiding abnormal stop of data transfer and abnormal heat generation of the circuit due to continuous high-speed data transfer. Can do.

3. Embodiment 3
3-1. Overview In the second embodiment, the image capturing apparatus determines the timing of stopping data transfer by monitoring the temperature of the USB interface circuit and detecting an abnormality. However, a detection method other than temperature may be used.

  For example, in the data transfer to the host computer by the isochronous transfer method, when the state where the USB bus activation rate is high continues for a long time, the temperature of the interface circuit rises. In particular, the USB interface circuit is locally overheated. If the USB interface circuit is overheated, an error is likely to occur in data transfer from the USB interface circuit 24c to the host computer.

  Also, transfer errors occur due to factors other than temperature. For example, even when the buffer inside the image processing circuit becomes full, a transfer error is likely to occur.

  Therefore, in this embodiment, the image capturing apparatus detects an abnormality by confirming the number of errors in data transfer from the USB interface circuit to the host computer, and stops data transfer. Then, after waiting for the set fixed time, the image capturing apparatus resumes data transfer.

3-2. Configuration FIG. 6 is a block diagram showing the configuration of the image capturing apparatus of this embodiment.

  The abnormality detection unit 25c of the present embodiment includes a USB interface error transfer counter circuit 28 and a clock generation circuit 27c. Other configurations are the same as those of the second embodiment.

  The USB interface error transfer counter circuit 28 detects a transfer error from the USB interface circuit 24c to the host computer 10c, and counts the number of continuous transfer errors. The USB interface error transfer counter circuit 28 compares the number of continuous data transfer errors from the USB interface circuit 24c to the host computer 10c with a preset threshold value, and sends a clock stop signal or a clock stop signal to the clock generation circuit 27c according to the comparison result. Send a clock enable signal. The threshold value set here may be changeable by an internal register or the like.

  The clock generation circuit 27c generates a clock necessary for the operation of each block of the image capturing device 20c. The clock generation circuit 27c switches between supply / stop of the clock to the image processing circuit 23c in accordance with the clock stop signal / permission signal from the USB interface error transfer counter circuit 28.

3-3. Operation The operation of the image capturing apparatus 20c of this embodiment will be described with reference to FIGS. FIG. 7 shows a flowchart of the image capturing / transferring process in the third embodiment of the present invention.

  When the image capturing device 20c receives an image capturing start command from the host computer 10c, the image capturing device 20c transmits settings such as the designated image size and frame rate to the CMOS sensor 30c via the CMOS sensor control circuit 22c and the CMOS sensor interface circuit 21c. To do. Then, the CMOS sensor 30c starts an image pickup operation and an image data transfer operation to the image pickup device 20c (S202).

  The image data input from the CMOS sensor 30c to the image capturing device 20c is subjected to processing such as color tone correction and compression by the image processing circuit 23c (S203).

  The USB interface error transfer counter circuit 28 detects the number of continuous error transfers from the USB interface circuit 24b to the host computer 10c, and compares the number of continuous error transfers with a preset threshold value (S204).

  At this time, if the continuous error transfer number of the USB interface circuit 24c is smaller than a preset threshold value, the image processing circuit 23c transfers the processed image data to the host computer 10c via the USB interface circuit 24c (S205).

  Thereafter, the USB interface error transfer counter circuit 28 checks whether there is an error in data transfer from the USB interface circuit 24c to the host computer 10c (S206). At this time, if there is no transfer error, the USB interface error transfer counter circuit 28 sets the number of continuous error transfers to zero (S207). If there is a transfer error, the USB interface error transfer counter circuit 28 increments the number of continuous error transfers (S211).

  The image processing (S203) and the transfer processing (S205) are repeated until a request for completion of imaging is received from the host computer 10c, thereby realizing moving image data transfer to the host computer 10c.

  On the other hand, if the number of continuous error transfers of the USB interface circuit 24c is greater than or equal to the threshold value in step S04, the image capturing device 20c shifts to the heat dissipation mode (S221).

  In the heat dissipation mode, the USB interface error transfer counter circuit 28 transmits a clock stop signal to the clock generation circuit 27c. Thereby, the clock generation circuit 27c stops the clock to the image processing circuit 23c (S222). After the clock is stopped, the image capturing apparatus 20c waits for a preset time (S223). The clock generation circuit 27c internally generates a clock restart signal after a certain time, and restarts transmission of the clock to the image processing circuit 23c.

  The subsequent operations are the same as those in the second embodiment.

  Next, the operation of the image pickup device 20b will be described in accordance with the temperature change of the USB interface circuit 24c. FIG. 8 is a timing chart at the time of image transfer processing of the image capturing apparatus 20b of the present embodiment.

  The shaded area in FIG. 8D indicates data transfer including an error. FIG. 8E shows changes in the number of USB interface error transfers. The other charts have the same meaning as in FIG.

  Imaging of the subject is started, and processing of the image data A input from the CMOS sensor 30c is started (timing T1). Image data A captured by the CMOS sensor 30c is transferred as image data a to the host computer 10c via the USB interface circuit 24c (timing T2).

  By repeating the image processing and the transfer processing, a state where the USB bus activation rate is high is maintained, so that the temperature of the USB interface circuit 24c rises (timing T3). As the temperature of the USB interface circuit 24c rises, an error is likely to occur in data transfer to the host computer 10c. The hatched portion in FIG. 8D indicates data including an error. Data c, k,... Containing errors are discarded by the host computer 10c.

  At timings T4 and T5, an error occurred only once, but no error occurred continuously. Therefore, the USB interface error transfer count increases only to 1 (triangular waveform in FIG. 8E).

  The higher the temperature of the USB interface circuit 24c, the more likely an error will occur in data transfer to the host computer 10c.

  By continuing the image processing and the transfer processing, the temperature of the USB interface circuit 24c further rises, thereby causing many transfer errors. Therefore, as shown in FIG. 8 (e), the number of continuous error transfers of the USB interface circuit 24c increases as the temperature rises. When the number of continuous error transfers becomes equal to or greater than the threshold, the image capturing device 20c shifts to the heat dissipation mode (timing T7).

  In the heat dissipation mode, the clock generation circuit 27c stops the clock signal to the image processing circuit 23c (period C in FIG. 8 (f)), thereby transferring data to the host computer 10c only for a predetermined period (FIG. 8 ( d) period t1) stop.

  In the heat dissipation mode, image data from the CMOS sensor 30c is input, but the image pickup device 20c always responds to zero-length in response to a data request from the host computer 10c. The data r transferred halfway is discarded (timing T7). Further, since the data r transferred to the host computer 10c has not been transmitted all data, the display on the host computer 10c remains displaying the image data q which has finally sent all the data.

  In the heat dissipation mode, since data transfer to the host computer 10c does not occur, a state where the USB bus activation rate is low is maintained (period t1 in FIG. 8D). Thereby, the temperature of the USB interface circuit 24c can be lowered (timing T8).

  When a preset time (period C in FIG. 8F) elapses after the clock generation circuit 27c stops the clock to the image processing circuit 23c, the image pickup device 20c shifts to the normal mode (T9). . When the normal mode is entered, the clock generation circuit 27c resumes the transmission of the clock to the image processing circuit 23c. Thereby, the transfer of the image data from the image pickup device 20c to the host computer 10c is resumed.

3-4. Summary of the present embodiment In this embodiment, the abnormal state of the image capturing device 20c is detected by detecting the abnormal continuation of the error transfer of the USB interface circuit 24c by continuous and high-speed data transfer, and the host computer 10c. Stop data transfer to. By stopping the data transfer, the heat generation of the USB interface circuit 24c is suppressed, and the temperature can be lowered. Thereafter, after a predetermined time has elapsed, the image capturing apparatus 20c resumes data transfer to the host computer 10c.

  As described above, by detecting and dealing with abnormal continuity of error transfer of the host interface circuit, it is possible to avoid abnormal stop of data transfer and abnormal heat generation of the circuit due to continuous and high-speed data transfer.

4). Embodiment 4
4-1. Outline In the fourth embodiment of the present invention, if the temperature of the USB interface circuit is within a predetermined temperature range, heat generation of the USB interface circuit is suppressed by thinning without stopping the data transfer to the host computer. Further, when the temperature of the USB interface circuit reaches a predetermined temperature range or more, the data transfer to the host computer is stopped to further suppress the heat generation of the USB interface circuit and lower the temperature of the USB interface circuit. When the temperature at which the USB interface circuit can operate normally is reached, data transfer to the host computer is resumed.

4-2. Configuration FIG. 9 is a block diagram showing the configuration of the image capturing apparatus of the present embodiment.

  In addition to the configuration of the image pickup apparatus shown in the second embodiment, the image pickup apparatus 20d of this embodiment further includes a USB transfer control circuit 29.

  The USB interface temperature detection circuit 26d of this embodiment transmits a clock stop signal or a clock permission signal to the clock generation circuit 27d, and transmits a thinning permission signal or a thinning prohibition signal to the USB transfer control circuit 29.

  When the USB transfer control circuit 29 receives the thinning permission signal from the USB interface temperature detection circuit 26d, the USB transfer control circuit 29 internally discards the image data from the image processing circuit 23d according to a preset thinning number, and the USB interface circuit 24d Do not send data. On the other hand, when receiving the thinning prohibition signal, the USB transfer control circuit 29 transmits all the image data from the image processing circuit 23d to the USB interface circuit 24d. A state in which a part of the image data is thinned out in this way and all the data is not transferred is called “thinning mode”.

  The thinning number set here may be changed by an internal register or the like.

4-3. Operation The operation of the image capturing apparatus 20d of this embodiment will be described with reference to FIGS. FIG. 10 shows a flowchart of an image capturing and transferring process according to the fourth embodiment of the present invention. However, here, the relationship of threshold 3> threshold 1> threshold 2 is satisfied.

  When the image capturing device 20d receives an image capturing start command from the host computer 10d, the specified image size, frame rate, and the like are set in the CMOS sensor 30d via the CMOS sensor interface circuit 21d and the CMOS sensor control circuit 22d. introduce. Then, the CMOS sensor 30d starts imaging and transmitting image data to the image capturing device 20d (S02).

  Image data input from the CMOS sensor 30d to the image pickup device 20d is subjected to processing such as color tone correction and compression by the image processing circuit 23d.

  The USB interface temperature detection circuit 26d detects the temperature of the USB interface circuit 24d, and compares the detected temperature with a preset threshold value 1 (S304).

  At this time, if the temperature of the USB interface circuit 24d is lower than the threshold value 1, the image processing circuit 23d transfers the processed image data to the host computer 10d via the USB interface circuit 24d (S305).

  The image capturing device 20d repeats the image processing (S303) and the transfer processing (S305) until receiving a request for the end of imaging from the host computer 10d, thereby realizing moving image data transfer to the host computer 10d.

  On the other hand, if the temperature of the USB interface circuit 24d is equal to or higher than the threshold 1 in step S304, the USB interface temperature detection circuit 26d next compares the temperature of the USB interface circuit 24d with the threshold 3 (S311).

  At this time, if the temperature of the USB interface circuit 24d is lower than the threshold 3, the image capturing device 20d shifts to the thinning mode (S312).

  In the thinning mode, the USB transfer control circuit 29 determines whether to transfer data to the USB interface circuit 24d according to a preset thinning number. When the USB transfer control circuit 29 determines that data is transferred, the USB transfer control circuit 29 transfers the data to the host computer 10d via the USB interface circuit 24d (S305).

  If the USB transfer control circuit 29 determines not to transfer data, the USB transfer control circuit 29 does not transmit anything to the USB interface circuit 24d, resulting in a zero-length response. By doing so, the image capturing apparatus 20d keeps the USB bus activation rate low and suppresses heat generation of the USB interface circuit 24d.

  On the other hand, if the temperature of the USB interface circuit 24d is equal to or higher than the threshold value 3 in step S11, the image capturing device 20d shifts to the heat dissipation mode (S321). The operation (S321 to S325) after shifting to the heat dissipation mode is the same as the operation (S111 to S115 in FIG. 4) in the second embodiment.

  Note that the imaging may be ended when the host computer 10d requests the end of imaging in the thinning mode and the heat dissipation mode.

  Next, the operation of the image pickup apparatus 20d will be described in accordance with the temperature change of the USB interface circuit 24d. FIG. 11 is a timing chart at the time of image transfer processing of the image capturing apparatus 20d of the present embodiment. The meaning of each chart is the same as in FIG.

  Imaging of the subject is started, and processing of the image data A input from the CMOS sensor 30d is started (timing T1). Image data A captured by the CMOS sensor 30d is transferred as image data a to the host computer 10d via the USB interface circuit 24d (timing T2).

  By repeating the image processing and the transfer processing, a state where the USB bus activation rate is high is maintained, so that the temperature of the USB interface circuit 24d rises (timing T3). When the temperature of the USB interface circuit 24d becomes equal to or higher than the threshold value 1, the image capturing device 20d shifts to the thinning mode (timing T4).

  In the thinning mode, data thinning is performed as in the period t1 and the period t2 in FIG. Here, data k and m transferred to the host computer 10d are thinned out. Since a zero-length response is performed instead of these data, the USB bus activation rate is lowered, and the heat generation of the USB interface circuit 24d is suppressed. Therefore, the temperature rise becomes more gradual (timing T5) than the temperature rise in the normal mode (one-dot long chain line in FIG. 11A).

  When the temperature of the USB interface circuit 24d becomes equal to or higher than the threshold value 2, the image capturing device 20d shifts to the heat dissipation mode (timing T6).

  The subsequent operations are the same as those in the second embodiment.

4-4. Summary of the present embodiment As described above, in the fourth embodiment of the present invention, the image capturing device 20d provides a plurality of threshold values for the temperature until the clock is stopped, and the temperature of the USB interface circuit 24d is within a predetermined temperature range. If there is, the data transfer to the host computer 10d is thinned out. By doing so, the image capturing device 20d can suppress the heat generation of the USB interface circuit without stopping the data transfer. Further, when the temperature of the USB interface circuit 24d reaches a predetermined temperature range or more, the image pickup device 20d further suppresses the heat generation of the USB interface circuit 24d by stopping the data transfer to the host computer 10d, and the USB interface circuit Reduce the temperature of 24d. When the temperature reaches a level at which the USB interface circuit 24d can operate normally, the image capturing device 20d resumes data transfer to the host computer 10d.

  As described above, the image capturing device 20d avoids abnormal stop of data transfer and abnormal heat generation of the circuit due to continuous and high-speed data transfer by thinning out or stopping the data transfer according to the temperature of the USB interface circuit 24d. can do.

5. Other Embodiments In the first to fourth embodiments, the example using the USB interface circuit has been described. However, the present invention is not limited to this. The present invention may be applied to a peripheral device control circuit using a PCI-Express bus or the like as an interface between the image pickup device and the host computer.

  Although Embodiments 2 to 4 have been described using an example in which a CMOS sensor is used as an image sensor, other image sensors such as a CCD may be used.

  In the first to fourth embodiments, the abnormality detection units 25, 25b,... Detect the presence / absence of an abnormal state of the host interface unit 24 (USB interface circuit 24b,...), But the camera interface unit 21 (CMOS sensor interface circuit 21b,. ..)) May be detected. In this case, when an abnormality is detected, data transfer in the camera interface unit 21 (CMOS sensor interface circuit 21b,...) Is controlled. The interface circuit abnormality determination and data transfer control upon abnormality detection are performed in the same manner as the control described in the above embodiments.

  In the first to fourth embodiments, the moving image capturing circuit is exemplified as the peripheral device, but the present invention is not limited to this. The present invention may be applied to a data transfer control device that interfaces with a peripheral device such as a reader / writer circuit for a memory card. FIG. 12 shows the configuration of the reader / writer circuit for the memory card. The reader / writer circuit 20e shown in FIG. 12 has a function of writing data transferred from the host device 10e to the memory card 30e, reading data from the memory card 30e, and transferring the data to the host device 10e. The reader / writer circuit 20e exchanges data with the host 10e via the host interface unit 24e. The reader / writer circuit 20e exchanges data with the memory card 30e via the card interface unit 21e. The card control unit 22e controls data writing / reading with respect to the memory card 30e. The abnormality detection unit 25e detects whether there is an abnormality in the host interface unit 24e or the card interface unit 21e, and stops data transfer in the interface units 24e and 21e when an abnormality is detected. The determination of abnormality and the control of data transfer at the time of abnormality detection are as described in the above embodiments.

  The present invention can also be applied when the interface circuit of the peripheral device is a MIPI (Mobile Industry Processor Interface) circuit.

DESCRIPTION OF SYMBOLS 10 Host apparatus 10b, 10c, 10d Host computer 20, 20b, 20c, 20d Image pick-up apparatus 21 Camera sensor interface part 21b, 21c, 21d CMOS sensor interface circuit 22 Camera sensor control part 22b, 22c, 22d CMOS sensor control circuit 23 Image Processing unit 23b, 23c, 23d Image processing circuit 24 Host interface unit 24b, 24c, 24d USB interface circuit 25, 25b, 25c, 25d Abnormality detection unit 26b, 26d USB interface temperature detection circuit 27b, 27c, 27d Clock generation circuit 28 USB Interface error transfer counter circuit 29 USB transfer control circuit 30 Camera sensor 30b, 30c, 30d CMOS sensor

Japanese Patent No. 3539264

Claims (10)

A data transfer control device for transferring data between a peripheral device and a host device,
A host interface unit capable of exchanging data with the host device;
A peripheral device interface unit capable of exchanging data with the peripheral device;
An abnormality detection unit for detecting an abnormal state of the host interface unit or the peripheral device interface unit;
When the abnormality detection unit detects an abnormality, the data transfer in the host interface unit or the peripheral device interface unit is interrupted, and then the abnormality detection unit is in a normal state of the host interface unit or the peripheral device interface unit A data transfer control device comprising: a transfer control unit that resumes a data transfer operation in the host interface unit or the peripheral device interface unit when recovery to the network is detected. A data processing unit for processing data input from the peripheral device;
2. The data transfer control device according to claim 1, wherein when the abnormality detection unit detects an abnormality, the processing of the data processing unit is interrupted.   3. The data transfer control device according to claim 2, wherein when the processing of the data processing unit is interrupted, the clock supply to the data processing unit is stopped.   4. The data transfer control according to claim 1, wherein the abnormality detection unit detects a temperature of the host interface unit or the peripheral device interface unit to determine an abnormal state. apparatus.   4. The abnormality detection unit according to claim 1, wherein the abnormality detection unit measures the number of data transfer errors of the host interface unit or the peripheral device interface unit and determines an abnormal state. 5. Data transfer control device.   The abnormality detection unit has a plurality of threshold values for determining an abnormal state of the host interface unit or the peripheral device interface unit, and controls the circuit activity rate of each interface unit according to the abnormal state based on each threshold value. 6. The data transfer control device according to claim 4 or 5, wherein:   The data transfer control device according to claim 1, wherein a threshold for the abnormality detection unit to determine an abnormal state can be changed.   8. The data transfer control device according to claim 1, wherein the host interface unit is a USB (Universal Serial Bus) interface circuit or a PCI-Express interface circuit.   8. The data transfer control device according to claim 1, wherein the peripheral device interface unit is a MIPI (Mobile Industry Processor Interface) circuit. An image capturing device capable of transferring image data captured by a camera sensor to a host device,
A host interface unit capable of exchanging data with the host device;
A camera sensor interface unit capable of exchanging data with the camera sensor;
An abnormality detection unit for detecting an abnormal state of the host interface unit or the camera sensor interface unit;
When the abnormality detection unit detects an abnormality, the data transfer in the host interface unit or the camera sensor interface unit is interrupted, and then the abnormality detection unit is in a normal state of the host interface unit or the camera sensor interface unit. An image capturing apparatus comprising: a transfer control unit that resumes a data transfer operation in the host interface unit or the camera sensor interface unit when recovery to the camera is detected.

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