JP4775329B2 - Electronic device, communication control device, and communication control method - Google Patents

Description

  The present invention relates to an electronic device that is connected to an external device having a communication function and operates by receiving power supply from the external device, a communication control device mounted on the electronic device, and a communication control method. The present invention relates to an electronic device, a communication control device, and a communication control method in which a ground potential is shared between a power supply terminal for power supply from an external device and a communication terminal for communication processing.

  2. Description of the Related Art Conventionally, secondary devices such as lithium ion batteries, nickel cadmium (NiCd) batteries, and nickel hydride batteries have been used as power sources in electronic devices such as video cameras and digital still cameras, mobile phones, and personal computers. Built-in battery packs are widely used. Today, microcomputers (hereinafter abbreviated as "microcomputers") are becoming cheaper and integrated circuits, and these battery packs have built-in microcomputers that communicate with electronic devices. ing.

  In this type of battery pack, the charge / discharge current of the battery cell is stored in the microcomputer and transmitted to the imaging device side, so that the remaining usage time can be displayed and the microcomputer can perform authentication processing with the imaging device side. In some cases, the fake battery cannot be used by executing (see, for example, Patent Document 1).

  In addition, as a communication method between electronic devices, for example, there are a “1-wire type” in which only one signal line is used and a “2-wire type” in which differential communication is performed using two signal lines. For example, a USB (Universal Serial Bus) cable includes two signal lines D + and D− in addition to a ground line and a power supply line (see, for example, Patent Document 2).

  By the way, when communicating between an electronic device and the battery pack connected thereto, these devices are connected by a power supply terminal, a GND (ground) terminal, and a signal terminal. Further, the wiring including each terminal has a resistance component due to contact resistance between the terminals and wiring resistance, and this resistance component may be several tens to several hundreds mΩ.

  On the other hand, the voltage level of the GND terminal is the GND level for the signal terminal and the GND level for the power supply terminal. For this reason, for example, when an operation with relatively large power consumption is executed on the electronic device side, such as driving a motor, a current of several A may flow through the GND wiring connected to the GND terminal. At this time, a potential difference of about several hundred mV is generated between the GND level on the electronic device side across the GND terminal and the GND level on the battery pack side.

  As described above, in a state where a large potential difference is generated between the GND level on the electronic device side and the GND level on the battery pack side, the reference voltage for transmitting and receiving signals varies greatly between the devices. May not be able to send / receive correctly. Hereinafter, such a situation will be specifically described by taking communication between the imaging device and the battery pack as an example.

  FIG. 8 is a diagram schematically illustrating an operation when a signal is transmitted from the imaging apparatus to the battery pack. FIG. 9 is a diagram schematically illustrating an operation when a signal is transmitted from the battery pack to the imaging apparatus.

  As shown in FIG. 8, on the imaging device side which is the transmission side, the lowest potential Vout_h at the H (high) level and the highest potential Vout_l at the L (low) level of the transmission signal are the potential Vout_gnd of the GND wiring on the transmission side. Is defined by the relative potential difference with reference to. On the other hand, on the battery pack side that is the receiving side, the lowest potential Vin_h for determining the H level of the received signal and the highest potential Vin_l for determining the L level are based on the potential Vin_gnd of the GND wiring on the receiving side. Is defined by the relative potential difference.

  Here, in FIG. 8, each of the above potentials is expressed as an absolute potential by a position in the vertical direction in the figure. As shown in FIG. 8A, if the conditions of Vout_h> Vin_h and Vout_l <Vin_l are satisfied as absolute potentials, the received data can be received normally. In this way, on the receiving side, by defining the difference between the determination threshold values of each level to be smaller than the potential difference between the H level and the L level specified on the transmitting side, it is possible to prevent voltage level fluctuations and the like. A margin is provided.

  Note that the current of the signal transmitted and received is sufficiently smaller than the current flowing through the GND wiring due to power consumption and charging operation on the imaging device side (for example, about 50 μA), so the voltage fluctuation of the signal between the transmission side and the reception side Therefore, the signal levels on the transmission side and the reception side are the same in FIG. On the other hand, a current of about 1 A may flow through the GND wiring even during normal operation due to power consumption and charging operation on the imaging device side. For this reason, the potential Vin_gnd of the absolute GND wiring on the battery pack side is lower than the potential Vout_gnd of the absolute GND wiring on the imaging device side.

  Even if the absolute GND potential is different between the reception side and the transmission side, if the current flowing through the GND wiring is relatively small and the above condition is satisfied, data transmission / reception can be performed normally. However, if the current flowing through the GND wiring becomes excessive and the difference in absolute GND potential becomes too large, the above condition is not satisfied. In the example of FIG. 8B, Vout_l> Vin_l is satisfied, and the reception side cannot correctly receive the L level.

The same situation can occur even when a signal is transmitted from the battery pack to the imaging device. Even in this case, as shown in FIG. 9A, if the conditions of Vout_h> Vin_h and Vout_l <Vin_l are satisfied as absolute potentials, the transmitted data can be received normally. However, if the current flowing through the GND wiring becomes excessive, the above condition is not satisfied if the absolute GND potential on the imaging device side increases excessively. In the example of FIG. 9B, Vout_h <Vin_h, and the receiving side cannot receive the H level correctly.
Japanese Patent No. 3838258 (paragraph numbers [0035] to [0042], FIG. 1) JP 2001-125589 A (paragraph number [0013], FIG. 10)

  By the way, in recent battery-driven electronic devices, the peak of internal power consumption tends to increase due to the demand for higher functionality and higher speed of operation, which causes a situation where a large current flows through the GND wiring. It has become easier. For example, in a digital imaging device, in order to shorten the imaging interval, signal processing / recording processing of captured image data, lens movement operation by a motor drive, and the like may be executed in parallel. In addition, the amount of data that is subject to signal processing and recording is also increasing. Therefore, a communication error due to the above-described difference in GND level tends to occur.

  Such a situation in which communication errors frequently occur can be avoided, for example, by separating the power supply GND wiring and the communication GND wiring. It can also be avoided by performing two-wire communication for transmitting and receiving differential signals. However, in communication between the battery pack and the electronic device, the configuration is simplified to reduce the manufacturing cost, or the number of terminals is reduced to prevent the occurrence of a failure at the time of attachment / detachment, and the degree of freedom in design is increased. Therefore, one-wire communication is often used. Therefore, even when performing one-wire communication, it has been desired that normal communication can be continued as stably as possible when the above situation occurs.

  The present invention has been made in view of such a problem, and an electronic device that operates by receiving power supply from an external device can stably perform communication processing with the external device even when an operation with a relatively large current consumption is performed. It is an object of the present invention to provide an electronic device that can be executed on the Internet, a communication control device mounted on such an electronic device, and a communication control method.

  In the present invention, in order to solve the above-mentioned problem, in an electronic device that is connected to an external device having a communication function and operates by receiving power supply from the external device, a power source for receiving power supply from the external device A communication processing unit that transmits and receives a signal based on the potential of the terminal and the ground terminal via the communication terminal, and a communication process with the external device by the communication processing unit, a predetermined series of communication A communication control unit that controls each communication task consisting of processing, and an internal operation management that manages whether or not the internal operation with relatively high power consumption during execution is specified in advance and the internal operation is executed in the electronic device A communication error occurs in the communication processing unit during the execution of the communication task, and the internal operation management unit performs the internal operation. There if it was recognized to have been executed, after resetting the communication processing unit, an electronic apparatus, characterized in that to execute the communication task which has been executed upon the occurrence of the communication error again is provided.

  In such an electronic device, a ground terminal is shared by a power supply terminal for supplying power from an external device and a communication terminal for communication processing. The communication processing in the communication processing unit is controlled and executed by the communication control unit in units of communication tasks including a predetermined series of communication processes. Further, among the internal operations executed by the electronic device, an internal operation with relatively high power consumption is defined in advance, and whether or not such an internal operation has been executed is managed by the internal operation management unit. Here, when a communication error occurs in the communication processing unit during the execution of the communication task, if the internal operation management unit recognizes that the internal operation defined in advance has been executed, the internal operation will cause a large It can be determined that a communication error has occurred due to the flow of current. For this reason, in such a case, after resetting the communication processing unit, the communication control unit re-executes the communication task that was being executed when the communication error occurred to restore the communication processing.

  According to the present invention, when a communication error occurs in the communication processing unit during the execution of the communication task, the internal operation is managed according to the predetermined internal operation execution management state managed by the internal operation management unit. It is possible to accurately determine whether or not a communication error has occurred due to a large current flowing through the grounding terminal. If the communication error is due to the internal operation, the communication process can be restored in a short time. Therefore, even when an operation with a relatively large current consumption is performed in the electronic device, the communication process with the external device can be executed more stably.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking as an example the case where the present invention is applied to an imaging apparatus realized as a digital still camera, a digital video camera, or the like.

FIG. 1 is a block diagram illustrating configurations of an imaging device and a battery pack according to the embodiment.
In FIG. 1, an imaging device 1 is a device driven by a power supply supplied from a battery pack 2, and includes a positive terminal 11 and a negative terminal 12, a communication terminal 13, and a microcomputer as a host controller for receiving power supply. (Hereinafter referred to as a host microcomputer) 14, a regulator 15, an imaging / recording processing unit 16, a display unit 17, a communication control circuit 18, and the like. The battery pack 2 that is detachably connected to the imaging device 1 has a communication function with the imaging device 1. The battery pack 2 includes a positive terminal 21 and a negative terminal 22 for supplying power, a communication terminal 23, a battery cell 24, a microcomputer (hereinafter referred to as a battery microcomputer) 25, a communication interface circuit 26, and the like.

  When the battery pack 2 is attached to the imaging apparatus 1, the positive terminal 21, the negative terminal 22, and the communication terminal 23 of the battery pack 2 are connected to the positive terminal 11, the negative terminal 12, and the communication terminal 13 of the imaging apparatus 1, respectively. . Then, power is supplied from the battery pack 2 to the imaging device 1 through the positive terminal 11 and the negative terminal 12.

  The host microcomputer 14 of the imaging device 1 is a control unit that controls the operation of the imaging device 1 in an integrated manner. The host microcomputer 14 can communicate with the battery pack 2 side by receiving a command to the communication control circuit 18 and receive desired data from the battery pack 2. Then, for example, using the received data, display information for displaying the remaining battery level is generated and output to the display unit 17.

  The communication control circuit 18 is a circuit in which an electrical interface circuit for communicating with the battery pack 2 side and a control circuit (CPU: Central Processing Unit) for controlling the communication procedure are integrated. (Integrated Circuit) etc. The communication control circuit 18 communicates with the battery pack 2 side via the communication terminal 13 in accordance with a command from the host microcomputer 14.

  The communication control circuit 18 and the host microcomputer 14 are connected by a parallel communication interface. The communication control circuit 18 and the communication interface circuit 26 of the battery pack 2 are connected by a single communication line via the communication terminals 13 and 23, and so-called one-wire communication is performed.

  The regulator 15 stabilizes the power supply voltage applied to the positive terminal 11 and the negative terminal 12 to a predetermined voltage, and supplies it to the inside of the apparatus. The imaging / recording processing unit 16 is a block that performs processing such as imaging of an image, recording of image data obtained by imaging on a recording medium, generation of an image being captured and display data of the recorded image, and the like. The display unit 17 includes, for example, an LCD (Liquid Crystal Display) or the like, and displays an image in response to display data generated by the imaging / recording processing unit 16 and the host microcomputer 14.

  On the other hand, the battery pack 2 supplies the voltage generated by the battery cell 24 to the imaging device 1 through the positive terminal 21 and the negative terminal 22. As the battery cell 24, for example, a lithium ion type secondary battery can be used. In addition, by using a secondary battery having a discharge characteristic in which the discharge voltage is relatively gradual and linearly reduced, such as a lithium ion secondary battery, the remaining amount of the battery is detected with high accuracy on the imaging device 1 side. For example, the remaining battery level can be displayed as the remaining usable time.

  The battery microcomputer 25 detects the voltage of the battery cell 24 and the current flowing through it. Further, it communicates with the communication control circuit 18 of the imaging device 1 via the communication interface circuit 26 and the communication terminal 23, and processes and responds to authentication information transmitted from the imaging device 1 side, or requests from the imaging device 1 side. Send the transmitted data.

  The communication interface circuit 26 is an electrical interface circuit for communicating with the imaging apparatus 1 side, and transmits and receives signals to and from the imaging apparatus 1 side via the communication terminal 23. The communication interface circuit 26 and the battery microcomputer 25 are connected by a parallel communication interface.

  Here, the purpose of communication between the imaging device 1 and the battery pack 2 is mainly to display the remaining battery level on the imaging device 1 side and to confirm that the connected battery pack 2 is the correct communication partner. (Authentication processing) and writing a use history in the battery pack 2.

  The battery remaining amount is displayed as follows. In the battery microcomputer 25, the battery microcomputer 25 measures the voltage and discharge current (or charge current or charge / discharge current) of the battery cell 24 via a built-in AD converter. The discharge current can be measured based on the voltage across the current detection resistor 27. The battery microcomputer 25 calculates information to be transmitted to the imaging device 1 from these voltage and discharge current measurement information. For example, an integrated value obtained by integrating the discharge current at a constant period is calculated.

  The battery microcomputer 25 transmits these pieces of information in response to a request from the imaging device 1. In the imaging apparatus 1, the host microcomputer 14 holds information such as power consumption in the imaging apparatus 1 in advance, and from this held information and information supplied from the battery pack 2, for example, a battery cell 24. The remaining amount information such as the remaining time that can be used is calculated. Then, a remaining amount display image corresponding to the calculation result is displayed on the display unit 17.

  In the authentication process for the battery pack 2, for example, both the host microcomputer 14 and the battery microcomputer 25 hold a plurality of unique data, and the battery microcomputer 25 includes the communication interface circuit 26, the communication terminal 23, and the communication terminal 13. The communication control circuit 18 is communicated with the communication control circuit 18 a plurality of times. The host microcomputer 14 decrypts the unique data on the battery microcomputer 25 side supplied through the communication control circuit 18 with the key information, and then compares the unique data held by itself with the battery pack 2 as the correct communication partner. Make sure that there is. When the host microcomputer 14 determines that the communication partner battery pack 2 is not legitimate, for example, the imaging device 1 is shifted to a power-off state and controlled so that the unauthorized battery pack 2 cannot be used.

  In the process of writing the usage history to the battery pack 2, the recording data using the battery pack 2 is transferred from the host microcomputer 14 via the communication control circuit 18, the communication terminal 13, the communication terminal 23, and the communication interface circuit 26. 25 and the battery microcomputer 25 stores the data. For example, when the battery pack 2 is attached to a charger or the like, the data stored in the battery microcomputer 25 is read out for display on the charger as “time available when inserted into the imaging device 1”. .

  In the present embodiment, the host microcomputer 14 performs the above-described communication process for displaying the remaining battery level, the communication process for the authentication process, and the communication process for writing the usage history. Manage tasks and usage history tasks. Each task is designated by a control command to the communication control circuit 18 so that the communication control circuit 18 automatically executes a series of communication processes corresponding to the designated task. Furthermore, after the communication process is executed, the host microcomputer 14 transmits a control command for requesting the execution result of the task to the communication control circuit 18 to thereby obtain predetermined information corresponding to the executed communication process. Is transmitted from the communication control circuit 18 to the host microcomputer 14, and the host microcomputer 14 can determine whether or not the designated processing is correctly executed.

  Here, a basic process at the time of communication between the imaging apparatus 1 and the battery pack 2 will be described by taking as an example a case where a battery remaining amount display task is requested. FIG. 2 is a timing chart schematically showing processing at the time of execution of the battery remaining amount display task.

  The communication control circuit 18 manages the processing contents corresponding to each task as one or more subtasks. For example, as shown in FIG. 2, the battery remaining amount display task is composed of five subtasks: communication reset, battery voltage acquisition, battery current acquisition, battery temperature acquisition, and battery deterioration rate acquisition.

  When a task execution command for instructing execution of the battery remaining amount display task is transmitted from the host microcomputer 14 to the communication control circuit 18 at timing T11, the CPU in the communication control circuit 18 analyzes the control command. Then, the subtasks corresponding to the battery remaining amount display task are executed in a predetermined order. Basically, in the processing of each of these subtasks, control information for executing predetermined processing and data necessary for processing are transmitted from the communication control circuit 18 to the communication interface circuit 26 of the battery pack 2. The When response data is returned from the communication interface circuit 26 in response to the transmission operation, the communication control circuit 18 makes a request based on, for example, a check sum given to the response data. It is determined whether or not the process has been correctly executed. If the process has been executed correctly, the next subtask is executed.

  At timing T <b> 12, the communication control circuit 18 transmits control information for instructing communication reset and data necessary for the processing to the communication interface circuit 26 of the battery pack 2. After receiving the response from the communication interface circuit 26, the communication control circuit 18 transmits control information requesting voltage data for displaying the remaining amount of the battery cell 24 to the communication interface circuit 26 at the next timing T13. . When voltage data is received from the communication interface circuit 26, it is temporarily stored in an internal RAM (Random Access Memory).

  At the next timing T14, the communication control circuit 18 requests current data of the battery cell 24, receives this data from the communication interface circuit 26, and stores it in the RAM. At the next timing T15, the temperature data of the battery cell 24 is requested, and this data is received from the communication interface circuit 26 and stored in the RAM. At the next timing T16, the deterioration rate data of the battery cell 24 is requested, and this data is received from the communication interface circuit 26 and stored in the RAM. Thereafter, the communication control circuit 18 waits for a command from the host microcomputer 14 while holding the data received by the above subtasks in the RAM.

  The host microcomputer 14 transmits a result request command corresponding to the task execution command to the communication control circuit 18 at a timing T17 when a predetermined time has elapsed from the transmission of the task execution command. When receiving the result request command, the communication control circuit 18 returns information indicating whether or not the corresponding task has been correctly executed to the communication control circuit 18. In this example, the received data stored in the RAM is further transferred to the communication control circuit 18. The host microcomputer 14 can determine the normal end of the task, and can calculate the remaining battery level based on the received data and the power consumption data of the imaging device 1 and display it on the display unit 17.

The execution of such a battery remaining amount display task is instructed by the host microcomputer 14 at regular intervals, whereby the remaining amount display on the display unit 17 is updated.
The authentication processing task includes, for example, three subtasks respectively corresponding to a communication reset process, a process for transmitting unique data for authentication to the battery microcomputer 25 side, and a process for receiving unique data from the battery microcomputer 25 side. The Further, the usage history task includes, for example, two subtasks respectively corresponding to a communication reset process and a process of transmitting and recording the usage history data of the battery pack 2 to the battery microcomputer 25 side.

  Here, FIG. 3 is a diagram illustrating a configuration example of a memory area included in the communication control circuit of the imaging apparatus. Here, as an example, only the memory area required when the battery remaining amount display task is executed is shown.

  The RAM 18a mounted in the communication control circuit 18 includes, for example, a remaining amount display task area 30 for executing a battery remaining amount display task and a communication management area 40 for managing execution of communication processing. Two memory areas are reserved. In the remaining amount display task area 30, a reception data valid flag 31, a subtask execution pointer 32, and reception data 33 to 36 from the battery pack 2 side are stored. The communication management area 40 stores error count data 41 and a communication error flag 42.

  The reception data valid flag 31 is data to be received from the battery pack 2 side by executing a task (here, a battery remaining amount display task) instructed from the host microcomputer 14 after the operation of the imaging apparatus 1 is started. Is a flag indicating whether or not one has been normally received.

  The subtask execution pointer 32 is information indicating a subtask to be executed next in the battery remaining amount display task. This value may indicate, for example, a line to be executed next in the program stored in the memory in the communication control circuit 18, or may simply be a number for identifying a subtask.

  In this example, the received data 33 to 36 are data areas corresponding to four subtasks (battery voltage acquisition process, battery current acquisition process, battery temperature acquisition process, battery deterioration rate acquisition process) included in the battery remaining amount display task. It has become.

  For example, after the operation of the imaging device 1 is started by power supply from the battery pack 2 and the authentication processing task is normally executed and the battery pack 2 is authenticated, the host microcomputer 14 executes the battery remaining amount display task. Is instructed, the communication control circuit 18 sequentially executes the corresponding subtasks according to the above-described procedure. At this time, the subtask execution pointer 32 is sequentially updated in accordance with the execution of the subtask.

  When the battery voltage, the battery current, the battery temperature, and the battery deterioration rate are sequentially transmitted from the battery pack 2 side by the execution of each subtask, the communication control circuit 18 stores these data in the received data 33 to 36 area. I will do it. When any one of the received data 33 to 36 by these subtasks is received, the communication control circuit 18 changes the received data valid flag 31 from “0” to “1”. As described above, if the execution of the corresponding task is started even once and at least one received data is normally received, the received data valid flag 31 is set to “1”. As another example, when the corresponding task is completed normally even once (that is, when all of the received data 33 to 36 are normally received even once), the received data valid flag 31 is set to “ It may be 1 ″.

  The received data 33 to 36 are transmitted to the host microcomputer 14 in response to a result request command from the host microcomputer 14. When next execution of the same task is instructed, the received data 33 to 36 are sequentially rewritten according to the execution of the corresponding subtask. At this time, the reception data stored before may be held without being erased until the next reception data is received from the battery pack 2 side.

  The error count data 41 indicates the communication error occurrence count when one communication process corresponding to the subtask is executed. When a communication error occurs due to the communication process corresponding to the subtask, the communication control circuit 18 retries the communication process a predetermined number of times. At this time, the number of error occurrences is integrated by the error number data 41. If normal communication is not possible after a predetermined number of retries, the communication error flag 42 is changed from “0” to “1”, and the process is shifted to the process stop state.

  When the communication control circuit 18 receives the result request command from the host microcomputer 14, it returns either “normal end”, “during communication”, or “communication error” as information indicating its own state. For example, if the communication error flag 42 is “1”, a “communication error” is transmitted. If this flag is “0”, the “normal end” is determined based on the subtask execution pointer 32 and the error count data 41. "Or" Communicating ". For example, if the subtask execution pointer 32 has not returned to the initial state, it can be determined that “communication is in progress”.

  Further, when transmitting “normal end”, the communication control circuit 18 reads and transmits the received data 33 to 36 together with this. Accordingly, only when the communication control circuit 18 can determine that the communication has been completed normally, the host microcomputer 14 can determine that the received data held therein has been received correctly and take it in.

  Here, as an example, the remaining amount display task area 30 corresponding to the battery remaining amount display task has been described. However, there is another task including a process of transferring information acquired from the battery pack 2 side to the host microcomputer 14. May be provided with a memory area corresponding to the task. In this case, similarly to the remaining amount display task area 30, the received data stored in the memory area is returned together with information indicating “normal end” when a result request command from the host microcomputer 14 is received.

  By the way, the wiring connected between the imaging device 1 and the battery pack 2 via the connection terminal has a resistance component of several tens to several hundreds mΩ due to contact resistance between the terminals and wiring resistance. Further, the voltage level of the wiring (GND wiring) connected through the negative terminals 12 and 22 is the GND level for the wiring connected through the positive terminals 11 and 21, and is transmitted / received through the communication terminals 13 and 23. This is also the GND potential for the signal.

  The current of the signal transmitted / received to / from the battery pack 2 in the communication control circuit 18 is, for example, about 50 μA, and the absolute fluctuation amount of the signal voltage between the imaging device 1 side and the battery pack 2 side is ignored. It will be possible. On the other hand, when an operation with relatively large power consumption is executed by the imaging / recording processing unit 16, a current of several A flows through the positive terminals 11 and 21, and this current also flows through the GND wiring. When such a large current flows, a large potential difference of several hundred mV occurs in the absolute GND level between the imaging device 1 side and the battery pack 2 side due to the resistance component of the GND wiring. Correct communication between the imaging device 1 and the battery pack 2 may not be possible.

  In particular, in an imaging device having a relatively high function, such as an imaging device capable of exchanging lenses, it is required to increase the imaging operation and the signal processing associated therewith. For example, in order to shorten the imaging interval, signal processing and recording processing of captured large-capacity image data, strobe lighting / charging operation, lens movement operation by motor drive for focus adjustment and exposure adjustment for the next imaging May be executed in parallel. In addition, there is a model that requires an operation of flipping the mirror by driving a motor during imaging. When the power consumption temporarily increases due to such an operation, there is a possibility that a large current exceeding 5 A, for example, flows through the GND wiring, and thus, between the imaging device 1 and the battery pack 2. The frequency of communication errors will increase.

  In the imaging apparatus 1 of the present embodiment, even when such a situation occurs, the communication error is quickly recovered, and processing on the imaging apparatus 1 side using information obtained by communication (for example, battery remaining amount display) In addition, the influence of communication errors should be avoided as much as possible. The operations that consume relatively large power as described above can be specified in advance, and it is natural that the host microcomputer 14 that controls these operations is executing these operations. Can be easily recognized. Therefore, in this imaging device, when it is determined that the above operation has been performed when a communication error occurs, only the necessary part is reset without completely resetting the entire device. The above-mentioned purpose is achieved by resuming the operation interrupted at.

FIG. 4 is a diagram illustrating an example of operation management data held by the host microcomputer of the imaging apparatus.
The RAM 14a mounted on the host microcomputer 14 stores a shutter release ON flag 51 and a strobe charge flag 52 as information for managing the above-described operation with large power consumption.

  The host microcomputer 14 changes the shutter release ON flag 51 from “0” to “1” when instructing the imaging / recording processing unit 16 to record the captured image data in response to pressing of the shutter release button or the like. Let When recording of the captured image data is instructed, the image capturing / recording processing unit 16 performs various signal processing for recording on the image data captured from the image sensor, and records the processed data on the recording medium at a high speed. To be executed. In parallel with such processing, focus adjustment and exposure adjustment for an image currently being picked up are continued. For this reason, a lens moving operation by motor drive may be executed.

  In addition, when the host microcomputer 14 instructs the image capturing / recording processing unit 16 to emit strobe light when instructing to record the captured image data as described above, the charging operation of the strobe charging circuit is thereafter performed. Is started, the strobe charge flag 52 is changed from “0” to “1”. Note that, for example, when the signal processing or recording processing of the recording data as described above and the strobe charging operation are executed in parallel, the strobe charging flag 52 is not particularly necessary.

  The host microcomputer 14 changes the shutter release ON flag 51 and the strobe charge flag 52 to “1” and then returns the values to “0” when the operation corresponding to each flag is completed. However, when each flag is set to “0”, a task that passes received data from the battery pack 2 side to the host microcomputer 14 such as the battery remaining amount display task is executed (that is, the task) If the result request command corresponding to the task is sent and the response is received, the values of these flags are held at “1”. Try to continue. As a result, when a communication error occurs in the communication control circuit 18, it can be reliably determined whether or not the cause is due to the operation corresponding to each flag.

  As another example, when an operation corresponding to each of the above flags is completed, if a predetermined task such as a battery remaining amount display task is being executed, each flag is set to “1” for a certain period thereafter. It may be held at "."

  Next, processing that is executed using the various data described above when a communication error due to a large current occurs in the communication control circuit 18 will be specifically described. FIG. 5 is a timing chart showing the operation of the imaging apparatus when a communication error occurs.

  At timing T <b> 21, the host microcomputer 14 transmits a task execution command for instructing execution of the battery remaining amount display task to the communication control circuit 18. The communication control circuit 18 that has received this command executes the corresponding subtasks sequentially from the timing T22, and communicates with the communication interface circuit 26 of the battery pack 2.

  Here, it is assumed that a current exceeding the threshold value Vth flows in the GND wiring due to the operation in the imaging / recording processing unit 16 in the period of the timing T23 to T26. In the communication control circuit 18 that is executing the instructed task, a communication error (indicated as “E” in the figure) due to the fluctuation of the GND level occurs when the subtask is executed after the timing T23. When a communication error occurs, the communication control circuit 18 retries the same communication process a predetermined number of times (here, twice). If communication cannot be performed normally, the communication control flag 18 sets the communication error flag 42 to “1”. Transition to the stop state (timing T24).

  After transmitting the task execution command, the host microcomputer 14 transmits a result request command to the communication control circuit 18 at a timing T25 when a predetermined time has elapsed. At this time, the communication control circuit 18 returns information indicating “communication error”, whereby the host microcomputer 14 detects that a communication error has occurred.

  When the host microcomputer 14 detects the occurrence of a communication error, the host microcomputer 14 refers to the shutter release ON flag 51 and the strobe charge flag 52. If any one of these flags is “1”, the host microcomputer 14 determines that the communication error is caused by an operation with large power consumption, and issues a reset command to the communication control circuit 18 at the next timing T27. Send and request a reset. However, the reset command at this time is a control command for instructing a dedicated reset when a communication error occurs (hereinafter referred to as a communication reset command), and the communication control circuit 18 receives at least received data 33 from the communication interface circuit 26. The reset process is performed while holding .about.36. Thereafter, at timing T28, the communication control circuit 18 finishes the reset process and transitions to the normal process state.

  If any of the above flags is not “1” after detecting the occurrence of a communication error, it can be determined that the communication error is caused by another cause. At this time, the host microcomputer 14 determines that the regular battery pack 2 is not connected, and controls the operation of the imaging device 1 to stop as usual. Alternatively, a control command for completely resetting the communication control circuit 18 to return to the start-up state is transmitted, and after the communication control circuit 18 is restarted, the authentication process with the battery pack 2 is executed again. If the authentication is correctly performed, another task such as a battery remaining amount display task may be executed.

  The host microcomputer 14 transmits again the same result request task transmitted at the timing T25 at the timing T29 when a predetermined time has elapsed from the transmission of the communication reset command (timing T27). The communication control circuit 18 returns information indicating “normal end” to the host microcomputer 14 and returns the received data from the communication interface circuit 26 that has been held to the host microcomputer 14.

  This received data includes at least data that has been successfully received from the battery pack 2 at the time of execution of the previous battery remaining amount display task (timing T22). The host microcomputer 14 recalculates the battery remaining amount based on the returned data, and updates the remaining amount display on the display unit 17. For example, the measurement values that are highly necessary in the calculation of the remaining battery level are the voltage and current of the battery cell, and the battery temperature and the battery deterioration rate are used to correct the remaining battery level calculated from the voltage and current. The Therefore, even when a communication error occurs, if the battery cell voltage and current can be received, the remaining battery level can be temporarily calculated based on these values and displayed on the display unit 17.

  Thereafter, at timing T30, the host microcomputer 14 transmits again a task execution command instructing execution of the battery remaining amount display task. Upon receiving this command, the communication control circuit 18 sequentially executes the corresponding subtasks from timing T31. When the result request command is received from the host microcomputer 14 at timing T32, the newly acquired received data is sent to the host microcomputer 14. The battery remaining amount display task is normally completed.

  In the above processing, when a communication error occurs in the communication control circuit 18 and the communication processing is stopped, the host microcomputer 14 operates with high power consumption based on the shutter release ON flag 51 and the strobe charging flag 52. It is recognized that a communication error has occurred, and the communication control circuit 18 is reset, and then the interrupted communication process is re-executed. Thereby, for example, communication processing can be restored in a shorter time than when the entire apparatus is reset or when the battery pack 2 is remounted.

  In particular, when the battery pack 2 having the mutual authentication function is used, when the entire apparatus is reset or the battery pack 2 is remounted, it is necessary to first execute the authentication processing task again. However, according to the above processing procedure, for example, the battery remaining amount display task can be re-executed without leaving time. Therefore, the above processing makes it possible to return the communication processing in a short time without reducing the safety of the imaging device 1.

  In addition, when a communication error occurs due to a large power consumption and a large current flowing through the GND wiring, a dedicated reset process for dealing with the situation is given to the communication control circuit 18 by a communication reset command. By executing it and not performing a complete reset process, the interruption time of the communication process can be shortened.

  Further, in the reset process by the communication reset command, the communication control circuit 18 leaves the data that has been successfully received from the communication interface circuit 26 at this time as it is, and the host microcomputer 14 immediately reads out the data after the reset process. By doing so, the influence of the communication error on the processing on the host microcomputer 14 side can be reduced. For example, it is possible to avoid such a situation that the remaining amount display displayed on the display unit 17 is interrupted or the accuracy of the remaining amount calculation is lowered.

  The above-described effects can be obtained between the image pickup apparatus 1 and the battery pack 2 while common power supply and GND wiring are used to perform one-wire communication. However, it is possible to realize an imaging apparatus that can be stably executed at high speed at low cost. Furthermore, the degree of freedom of arrangement of connection terminals, communication lines, circuits, and the like with the battery pack 2 can be increased, and the imaging device 1 can be downsized.

FIG. 6 is a flowchart showing a flow of reset processing by a communication reset command.
When the communication control circuit 18 receives a communication reset command from the host microcomputer 14 that has detected a communication error during execution of the remaining battery amount display task, for example, the following processing is executed. First, the subtask execution pointer 32 is cleared (step S11). Next, the received data valid flag 31 is referred to (step S12). If the value of the flag is “1”, an ACK (Acknowledge) is returned to the host microcomputer 14 (step S13), and then communication management is performed. The information in area 40 is cleared (step S14). On the other hand, if the value of the received data valid flag 31 is “0”, the information in the communication management area 40 is cleared without making any response to the host microcomputer 14 (step S14).

FIG. 7 is a flowchart illustrating a processing procedure of the host microcomputer of the imaging apparatus when a communication error occurs.
When a communication error is detected in the communication control circuit 18 after instructing execution of a task (in this case, a battery remaining amount display task) that transfers data from the battery pack 2 to the host microcomputer 14, the host microcomputer 14 The process after the next step S22 is executed. As described above, the host microcomputer 14 detects a communication error by returning information indicating a “communication error” from the communication control circuit 18 in response to the result request command. As another example, when a communication error occurs, the communication control circuit 18 may notify the host microcomputer 14 of the occurrence of the communication error.

  When detecting a communication error, the host microcomputer 14 refers to the values of the shutter release ON flag 51 and the strobe charge flag 52 (step S22). When both of these flags are “0”, the host microcomputer 14 executes a process for ending the operation of the entire imaging apparatus 1 (step S23). Alternatively, as described above, the entire imaging apparatus 1 may be reset and the authentication process with the battery pack 2 may be executed again.

  If either one of the shutter release ON flag 51 and the flash charge flag 52 is “1”, the host microcomputer 14 transmits a communication reset command to the communication control circuit 18 (step S24), and responds within a predetermined time. It is determined whether or not there is (step S25). If there is an ACK response, it can be determined that valid received data is stored in the RAM 18a of the communication control circuit 18, so that the host microcomputer 14 outputs a result request command for reading the received data after a predetermined time. It transmits to the communication control circuit 18 (step S26).

  When the received data is returned from the communication control circuit 18, the host microcomputer 14 receives it and executes a predetermined process (in this case, a battery remaining amount calculation process) using the received data (step S27). Then, the host microcomputer 14 transmits a task execution command (corresponding to the battery remaining amount display task in this case) again after a predetermined time thereafter, and requests the communication control circuit 18 to execute the interrupted task again. (Step S28).

  The received data returned to the host microcomputer 14 in step S27 is basically data that has been successfully received from the battery pack 2 side by the task that was executed immediately before and was interrupted. However, the received data stored once in the RAM 18a of the communication control circuit 18 is held without being erased until it is overwritten with new received data next, and according to the result request command. The specification may return all received data in the RAM 18a.

  On the other hand, if there is no response from the communication control circuit 18 in response to the transmission of the communication reset command (step S24), it can be determined that valid received data is not stored in the RAM 18a of the communication control circuit 18. The host microcomputer 14 transmits the task execution command again without transmitting the result request command, and causes the communication control circuit 18 to execute the interrupted task again (step S28).

  6 and 7, after the host microcomputer 14 detects an error, the host microcomputer 14 acquires it in the communication control circuit 18 depending on whether or not there is a response to the communication reset command from the communication control circuit 18. It is possible to determine whether or not there is reception data that can be received. If there is, the reception data can be immediately acquired and necessary processing can be temporarily executed. Conversely, if there is no received data that can be acquired in the communication control circuit 18, a task execution command can be immediately transmitted to re-execute the interrupted task.

  In the above description, the case where a communication error has occurred during the execution of the battery remaining amount display task has been described. However, other tasks such as passing some data from the battery pack 2 side to the host microcomputer 14 are described. Even during execution, the reset process is basically executed by the same procedure as in FIG. That is, at least data received from the battery pack 2 side is retained without being erased, and other information is reset. As a result, as much processing as possible can be executed using the received data before re-execution of the task. Further, the interrupted task can be immediately re-executed without resetting the entire apparatus or completely resetting the communication control circuit 18. Therefore, the imaging operation in the imaging device 1 can be speeded up.

  For example, in the case of an authentication processing task, if a communication error due to a large current occurs during its execution, after the communication processing of the communication control circuit 18 is stopped, a reset processing by a communication reset command is executed, and thereafter The authentication processing task is executed again.

  Conventionally, when a communication error occurs during the execution of an authentication processing task, it is determined that the connected battery pack 2 is not legitimate, the operation of the entire imaging apparatus 1 is terminated, and the battery pack 2 is renewed. The image pickup apparatus 1 is controlled not to be activated until it is attached. However, as in the process of FIG. 7, if either one of the shutter release ON flag 51 and the strobe charge flag 52 is “1”, a reset process by a communication reset command is executed to stop the entire imaging apparatus 1. Thus, it becomes unnecessary to remount the battery pack 2 by enabling the authentication processing task to be re-executed. In addition, the internal processing of the imaging apparatus 1 (for example, initial processing until the captured image can be recorded, exposure / focus adjustment processing, etc.) is continued as usual from the occurrence of a communication error to the completion of task re-execution. The imaging operation in the imaging apparatus 1 can be started in a short time from the start.

  Even in this example, if a communication error occurs during the execution of the authentication processing task, if both the shutter release ON flag 51 and the strobe charge flag 52 are “0”, the same as step S23 in FIG. (I.e., the same as when a conventional authentication error occurs), the entire operation of the imaging apparatus 1 is terminated.

  In this authentication processing task, data already received from the battery pack 2 side may be used after the reset processing by the communication reset command is executed.

  In the above embodiment, the host microcomputer 14 detects the occurrence of a communication error in the communication control circuit 18 and then performs communication due to an excessive current from the shutter release ON flag 51 or the strobe charge flag 52 to the GND wiring. In addition to this, for example, when an operation that sets these flags to “1” is executed, the host microcomputer 14 always sends a communication reset command to the communication control circuit 18. It may be. In this case, the communication control circuit 18 accepts a communication reset command only when a communication error occurs and the process is stopped, and ignores this command in other states. The processing after the communication control circuit 18 receives the communication reset command is as described above.

  In the above embodiment, the communication control circuit 18 is configured to operate according to the control command from the host microcomputer 14. However, the present invention is not limited to such a configuration. For example, the host microcomputer 14 controls all communication processes. It is good also as composition to do. The functions of the communication control circuit 18 and the host microcomputer 14 may be provided on an integrated semiconductor substrate.

  In the above-described embodiment, communication is performed between the imaging device 1 and the battery pack 2 using one communication line. However, communication may be performed using a plurality of communication lines. That is, the present invention can be applied to an electronic device that does not use a differential signal and transmits and receives a signal based on a potential common to the GND level of the power supply wiring.

  In the embodiment described above, the imaging apparatus is described as an example of the electronic device. However, the present invention is not limited to this, and the device operates by receiving power from an external device and has a communication function with the external device. The present invention can be applied to any electronic device. For example, the present invention can be applied to a portable device such as a music player having a function of performing some operation upon receiving power supply from a PC (personal computer) as an external device.

It is a block diagram which shows the structure of the imaging device and battery pack which concern on embodiment. It is a timing chart which shows typically processing at the time of execution of a battery remaining amount display task. It is a figure which shows the structural example of the memory area with which the communication control circuit of an imaging device is provided. It is a figure which shows the example of the data for operation management which the host microcomputer of an imaging device hold | maintains. It is a timing chart which shows operation of an imaging device at the time of communication error occurrence. It is a flowchart which shows the flow of the reset process by a communication reset command. It is a flowchart which shows the process sequence of the host microcomputer of an imaging device when a communication error generate | occur | produces. It is a figure which shows typically operation | movement in the case of transmitting a signal from an imaging device to a battery pack. It is a figure which shows typically operation | movement in case a signal is transmitted to an imaging device from a battery pack.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Imaging device, 2 ... Battery pack, 11, 21 ... Positive electrode terminal, 12, 22 ... Negative electrode terminal, 13, 23 ... Communication terminal, 14 ... Host microcomputer, 15 ... Regulator, 16 ... Imaging / recording processing unit, 17 ... display unit, 18 ... communication control circuit, 24 ... battery cell, 25 ... battery microcomputer, 26 ... communication interface circuit, 27 ... current detection resistor

Claims (11)

In an electronic device that is connected to an external device having a communication function and operates by receiving power supply from the external device,
A power supply terminal and a ground terminal for receiving power supply from the external device;
A communication processing unit that transmits and receives a signal based on the potential of the ground terminal via the communication terminal;
A communication control unit that controls communication processing with the external device by the communication processing unit in units of communication tasks including a predetermined series of communication processing;
An internal operation management unit that manages whether or not an internal operation with relatively high power consumption during execution is defined in advance and the internal operation is executed in the electronic device;
Have
When the communication control unit recognizes that a communication error has occurred in the communication processing unit and the internal operation is performed by the internal operation management unit during execution of the communication task, the communication control unit An electronic apparatus characterized by causing the communication task that was being executed when the communication error occurred to be executed again after resetting the processing unit. The communication processing unit includes a data storage unit that sequentially stores data received from the external device by execution of the communication task,
When the communication control unit determines that the communication error has occurred and the internal operation has been executed, the communication control unit continues to hold data normally stored in the data storage unit before the communication error occurs The electronic apparatus according to claim 1, wherein a communication error reset process for resetting the communication processing unit is executed. A data processing unit that executes predetermined processing using data acquired from the external device by execution of the communication task;
The communication control unit causes the communication processing unit to execute the communication error reset processing, reads the data stored in the data storage unit, causes the data processing unit to process, and then performs the communication error. The electronic device according to claim 2, wherein the communication processing unit is executed again when the communication task is executed at the time of occurrence. The external device is a battery pack that supplies power to the electronic device by a secondary battery,
The data processing unit has a function of calculating display capacity of the secondary battery and generating display information,
When the communication control unit causes the communication processing unit to execute a battery remaining amount task for receiving a plurality of detection data for calculating the remaining capacity from the battery pack as one of the communication tasks When the communication error has occurred and the internal operation has been executed, the communication processing unit is caused to execute the communication error reset process, and then the detection data stored in the data storage unit is stored. Is transferred to the data processing unit, the remaining capacity calculation and the display information generation processing are executed, and then the battery remaining amount task is executed again by the communication processing unit. The electronic device according to claim 3. The data processing unit further includes a function of executing an authentication process for determining whether or not the battery pack is genuine,
After the electronic device is activated, the communication control unit first performs an authentication task for transmitting / receiving authentication information necessary for the authentication process with the battery pack as one of the communication tasks. The battery remaining amount task is executed at regular intervals, and when the remaining battery amount task is executed, the communication error occurs and the internal operation is performed. When the determination is made, the communication processing unit is caused to execute the communication error reset process, and then the detection data stored in the data storage unit is read and transferred to the data processing unit to calculate and display the remaining capacity. Causing the communication processing unit to re-execute the battery remaining amount task without causing the authentication task to be re-executed. Electronic device according to claim 4, symptoms. When the communication processing unit is instructed to execute any of the communication tasks by a control command from the communication control unit, the communication processing unit automatically executes a series of communication processes constituting the communication task, and the communication task Storing process progress information for managing the progress of individual communication processes constituting the error information and error information indicating the occurrence of the communication error during the execution of the communication task,
3. When executing the communication error reset process, the data stored in the data storage unit is continuously held, and at least the process progress information and the error information are initialized. Electronic equipment. A data processing unit that executes an authentication process for determining whether or not the connected external device is a regular communication partner;
When the communication control unit causes the communication processing unit to execute an authentication task for transmitting / receiving authentication information necessary for the authentication processing to / from the external device as one of the communication tasks, The electronic device according to claim 1, wherein if it is determined that a communication error has occurred and the internal operation has been executed, the authentication task is executed again after resetting the communication processing unit.   The communication control unit, as one of the communication tasks, when causing the communication processing unit to execute an authentication task for transmitting and receiving authentication information necessary for the authentication processing with the external device, 8. The control according to claim 7, wherein, when a communication error occurs, if the internal operation management unit does not recognize that the internal operation has been executed, control is performed to end the operation of the electronic device. Electronics.   The electronic device according to claim 7, wherein the external device is a battery pack that supplies power to the electronic device by a secondary battery. In a communication control device that is mounted on an electronic device that operates by receiving power supply from an external device and communicates with the external device,
A communication processing unit that transmits and receives a signal based on a potential of a ground terminal of the electronic device for receiving power supply from the external device via a communication terminal;
A communication control unit that controls communication processing with the external device by the communication processing unit in units of communication tasks including a predetermined series of communication processing;
An internal operation management unit for managing whether or not the internal operation of the electronic device with relatively high power consumption at the time of execution is defined in advance and the internal operation is executed in the electronic device;
Have
When the communication control unit recognizes that a communication error has occurred in the communication processing unit and the internal operation is performed by the internal operation management unit during execution of the communication task, the communication control unit A communication control device that causes the communication task that was being executed when the communication error occurred to be executed again after resetting the processing unit. In an electronic device that operates by receiving power supply from an external device, a communication control method for communicating with the external device,
The communication control unit has predetermined communication processing in the communication processing unit that transmits and receives a signal based on the potential of the ground terminal of the electronic device for receiving power supply from the external device via the communication terminal. Execute by communication task unit consisting of a series of communication processing,
The internal operation management unit preliminarily defines the internal operation of the electronic device that consumes relatively high power during execution, and manages whether the internal operation is executed in the electronic device;
When the communication control unit recognizes that a communication error has occurred in the communication processing unit during execution of the communication task and the internal operation is performed by the internal operation management unit, the communication control unit After resetting the processing unit, the communication task that was being executed when the communication error occurred is executed again.
A communication control method characterized by the above.

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