JP2010134942A - Real-time clock and data recording method of real-time clock - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a real-time clock which improves the reliability of stored event data. <P>SOLUTION: The real-time clock 10 includes: an event detection circuit 20 which detects that event detection signals are input from the outside; a time measuring circuit 18 which generates time data, on the basis of signals output from an oscillation circuit 16; a memory 40; and a control circuit 42 which records event data to the memory 40, when the input of the event detection signals is detected by the event detection circuit 20, with the event data having additional data which indicates the operating state of the real-time clock 10, and the time data generated by the time-measuring circuit 18. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a real-time clock and a data recording method for the real-time clock.

  A real-time clock is known as an apparatus for recording time information when an event occurs in a memory provided in the device, and is disclosed in Patent Document 1, for example. The real-time clock disclosed in Patent Document 1 includes an oscillation circuit, a frequency dividing circuit, a time measuring circuit, an interface circuit, an operation control circuit, an event detection circuit, and an event storage memory. In the real-time clock having such a configuration, the event storage memory stores time information of event occurrence detected by the event detection circuit and information unique to the event that has occurred as one event data.

JP 2003-132470 A

  With the real-time clock configured as described above, it is possible to identify an event that occurred at the recording time based on the event information stored in the event storage memory. Here, Patent Document 1 describes that a real-time clock power supply system includes a main power supply that supplies power from a so-called outlet and a backup power supply that supplies power from a primary battery or a secondary battery. No measures have been taken against unexpected situations such as voltage drop and oscillation stop. For this reason, even if erroneous data is written in the event storage memory due to a voltage drop or the like, the correctness determination of the stored data cannot be performed. Therefore, the reliability of the stored specific event data is low.

  Therefore, an object of the present invention is to provide a real-time clock and a data recording method for the real-time clock capable of improving the reliability of stored event data (making it possible to determine whether the reliability is correct or not).

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A real-time clock that outputs time data, an event detection circuit that detects that an event detection signal is input from the outside, and the time data that is generated based on a signal output from the oscillation circuit Event data including additional data indicating an operation state of the real-time clock when the input of the event detection signal is detected by the time detection circuit, a memory, and the event detection circuit, and the time data generated by the time measurement circuit And a control circuit for recording the data in the memory.

  According to the real-time clock having such a configuration, the user can know the operation state of the real-time clock when the event data is recorded, and the reliability of the event data can be improved.

  Application Example 2 The real-time clock according to Application Example 1, including a voltage drop detection circuit that detects a drop in power supply voltage applied to a power supply terminal, and the additional data is detected by the voltage drop detection circuit. A real-time clock comprising voltage drop information, which is information indicating a drop in the power supply voltage.

  With such a configuration, it becomes possible to know the transition of the current voltage supplied to the real-time clock, in addition to improving the reliability of the event data.

  [Application Example 3] The real-time clock according to Application Example 2, wherein the voltage drop detection circuit includes a first voltage comparison unit that detects that the power supply voltage is lower than a first threshold value. The voltage drop detection information indicates that the first voltage comparison unit of the voltage drop detection circuit indicates that the power supply voltage is below the first threshold when the event detection circuit detects the input of the event detection signal. A real-time clock including information indicating whether or not it is detected.

  With such a configuration, it is possible to know what operating state the real-time clock is in depending on how the threshold is set.

  Application Example 4 The real-time clock according to Application Example 3, wherein the voltage drop detection circuit detects that the power supply voltage is lower than a second threshold value set lower than the first threshold value. The voltage drop detection information is detected by the second voltage comparison unit of the voltage drop detection circuit that the power supply voltage is lower than the second threshold value. A real-time clock characterized by including information indicating whether or not.

  With such a configuration, it is possible to improve analysis accuracy when a system error or the like occurs.

  Application Example 5 The real-time clock according to any one of Application Examples 1 to 4, further comprising an oscillation stop detection circuit that detects that the oscillation circuit has stopped oscillating, wherein the additional data is the oscillation stop A real-time clock comprising oscillation stop information indicating whether or not a detection circuit detects the oscillation stop.

  With such a configuration, even when the oscillation of the oscillator is stopped due to a factor other than a decrease in the power supply voltage, the detection can be performed, and whether the event data recorded in the memory is correct or not, specifically, the event data It is possible to determine whether the time data added to is correct or not. Therefore, the reliability of event data can be improved.

  [Application Example 6] The real-time clock according to any one of Application Examples 2 to 5, wherein a rising edge detection mode for detecting a rising edge of a voltage waveform of the event detection signal and a falling edge detection mode for detecting a falling edge A setting register capable of setting either one of the rising detection mode and the falling detection mode when the additional data is detected by the event detection circuit as input of the event detection signal; A real-time clock including detection information indicating whether or not is set in the setting register.

  With such a configuration, it is possible to detect the occurrence of events of various external devices. For example, in the case of an object that performs a pair of operations, such as opening and closing a door or lid, select either by assigning "Close → Open: Rise Signal" or "Open → Close: Fall Signal" Can be detected automatically. When a plurality of terminals are provided, both opening and closing operations can be detected.

  Application Example 7 The real-time clock according to any one of Application Examples 2 to 6, wherein a plurality of terminals for inputting the event detection signal are provided, and the control circuit is configured to input the event detection signal by the event detection circuit. And detecting the event data having the additional data, the time data, and the port number of the terminal to which the event detection signal is input, in the memory.

  According to such a configuration, different event occurrence signals are input and recorded for each input terminal, but by adding a port number for each terminal to the additional information, It is possible to know the terminal, that is, which event has occurred.

  Application Example 8 A data recording method of a real time clock having a function of recording time data at the time of event occurrence in a memory, the time data, and additional data for determining an operation state of the real time clock at the time of the event occurrence A real-time clock data recording method comprising: recording as event data having

  According to such a data recording method, the reliability of event data can be improved.

  Application Example 9 In the real-time clock data recording method according to Application Example 8, the additional data includes information that determines whether or not the power supply voltage applied to the power supply terminal is below a threshold value. A real time clock data recording method.

  By setting the determination information as described above, it becomes possible to know what operating state the real-time clock is in based on the determination information depending on the setting of the threshold value.

  Application Example 10 In the real-time clock data recording method according to Application Example 8, it is preferable that the additional data includes information that determines which of the plurality of voltage value ranges the applied voltage is included in. A real time clock data recording method.

  By making the determination information as described above, it becomes possible to grasp and analyze the operation state of the real-time clock based on the determination information in more detail, and to improve the reliability of the recorded event data. it can.

  Application Example 11 In the real-time clock data recording method according to Application Example 8, the additional data includes information indicating whether or not the oscillation stop of the oscillation circuit of the real-time clock is detected. Real-time clock data recording method.

  By including the information as described above in the additional data, it is possible to detect the information even when the oscillation of the oscillator is not caused by the power supply voltage. For this reason, it becomes possible to improve the reliability of the recorded event data.

It is a block diagram which shows the structure of the real-time clock which concerns on 1st Embodiment. It is a flow which shows operation | movement of a real-time clock. It is a block diagram which shows the structure of the real-time clock which concerns on 2nd Embodiment. It is a graph which shows the flow of flag raising accompanying the power supply voltage fall of the real time clock concerning a 2nd embodiment. It is a block diagram which shows the structure of the real-time clock which concerns on 3rd Embodiment.

Hereinafter, embodiments of the real-time clock according to the present invention will be described in detail with reference to the drawings. First, a first embodiment according to the real-time clock of the present invention will be described with reference to FIG.
As shown in FIG. 1, the real-time clock 10 according to the present embodiment includes an oscillator 12, a clock circuit 18, an event detection circuit 20, a voltage drop detection circuit 26, a setting register 34, a memory 40, a control circuit 42, and input / output processing. The circuit 46 is basically configured.

  The oscillator 12 includes a vibrator 14 and an oscillation circuit 16, and the vibrator 14 vibrates at a predetermined frequency when an electric signal is input through the oscillation circuit 16. The oscillation circuit 16 amplifies and outputs the signal output from the vibrator 14. Here, the configuration of the vibrator 14 is not particularly limited. However, in order to obtain a stable oscillation frequency in a wide temperature range, it is desirable to use one having good frequency-temperature characteristics. For example, when the vibrator 14 is a piezoelectric vibrator, the vibrating piece may be made of quartz.

  The clock circuit 18 is connected to the oscillator 12. When the signal output from the oscillator 12 is divided to obtain a frequency of 1 [Hz], the signal is output using this 1 [Hz] signal. , Month, day, hour, minute, and second are measured in each time register (not shown). By having such a timer circuit 18, time data can be obtained, and the date and time when an event occurs (every event detection cycle) can be recorded in the memory. In addition to the above year, month, day, hour, minute, and second, the timer circuit 18 can store data on the day of the week by setting.

  The event detection circuit 20 is connected to an event input terminal 22 that is an external terminal of the real-time clock 10. The event detection circuit 20 is configured to set an event generation flag when an electrical signal indicating that an event has occurred is input to the event input terminal 22. Thus, by indicating the occurrence of an event by a flag, it is possible to determine the presence or absence of the event based on the flag. Specifically, the event occurrence flag is set to 1 (changed from 0 to 1).

  The voltage drop detection circuit 26 is connected to a power supply terminal 28 that is an external terminal of the real-time clock 10 and includes a voltage comparison unit 30 therein. A voltage of a reference current is set in advance in the voltage comparison unit 30, and the voltage of the current (applied voltage) input to the power supply terminal 28 is compared with the reference voltage. The voltage drop detection circuit 26 is configured to set the voltage drop flag 32 when it is determined that the value of the input voltage compared by the voltage comparison unit 30 is lower than the value of the reference voltage. Specifically, when the voltage of the current input from the power supply terminal 28 becomes lower than the value of the reference voltage, the voltage drop flag 32 is set to 1 (changed from 0 to 1). For example, the reference voltage can be about 1.2V.

  The setting register 34 stores recording digit setting data 36 and an event detection period 38. Here, when the time is recorded in the memory 40, the control circuit 42, which will be described in detail later, provides a data area of 1 byte (8 bits) for each of year, month, day, hour, minute, and second, and the data The year, month, day, hour, minute, and second are serially arranged in a packed BCD (Binary Coded Decimal) for the area. The maximum value of the number shown as time data is “99” in the unit of “year”. When this numerical value is represented by an 8-bit binary number, it becomes “10011001”.

  The recording digit setting data 36 defines the number of digits of data (data combining time data and additional data) constituting event data described later. When the year, month, day, hour, minute, and second are each indicated by 1 byte as time data, 6 bytes (48 digits) are required, and 1 byte (8 digits) or 2 bytes (16 digits) are added as additional data. Set the value. The event detection period 38 is a period for confirming whether or not an event is detected in the event detection circuit 20 (whether or not the event occurrence flag 24 is standing). The recording digit setting data 36 and the event detection period 38 may be set by the user after the real-time clock 10 is shipped. What is necessary is just to write.

  The memory 40 is storage means for recording the time data, the data related to the event occurrence, and the data related to the voltage drop. In the memory 40, event data configured by a control circuit 42, which will be described in detail later, is recorded in an area allocated for each write address.

  The control circuit 42 is connected to the above-described timing circuit 18, event detection circuit 20, voltage drop detection circuit 26, setting register 34, memory 40, and interrupt output terminal 44 as an external terminal. The control circuit 42 is configured to be able to read the time data when it is detected that the flag is set based on the flag information input from the event detection circuit 20 or the voltage drop detection circuit 26 from the time measuring circuit 18. Yes. In the control circuit 42, various information detected by the event detection circuit 20 or the voltage drop detection circuit 26 is used as additional data, and processing for linking to the previous stage (first) of the time data at the time of event occurrence is performed. Here, the 8-bit data constituting the additional data may be indicated by at least the first two digits starting with “11”, that is, in the form of “11XXXXXXX”. As described above, since the maximum value of the 8-bit data constituting the time data starts with “10”, it is easy to distinguish it from the time data by adding the data starting with “11” to the head. . By displaying in this format, even if the user reads a plurality of event data all together and the data is displayed continuously, the top portion (“11”) of the additional data is It plays a role as a header of event data, and it becomes possible to easily determine the break of event data. When data related to voltage drop (applied voltage determination information) and data related to event occurrence are shown in one byte, the first two digits of the preceding four bits are used as a header, and the voltage drop is caused by either the last two digits. It is only necessary to indicate data and indicate unique data of an event that occurs in the subsequent 4 bits. That is, “11 (header) 01 (voltage drop data) XXXX (event specific data)” may be used.

  The interrupt output terminal 44 plays a role of interrupting and outputting a signal to the CPU simultaneously with recording of time data, data related to event occurrence, and data related to voltage drop when an arbitrary event input occurs.

  The input / output processing circuit 46 is an input / output interface, is connected to the setting register 34 and the memory 42, and is connected to a data input / output terminal 48 as an external terminal of the real-time clock 10. The input / output processing circuit 46 plays a role of outputting write data input via the data input / output terminal 48 to the setting register 34 and the memory 40 and reading event data recorded in the memory 40.

  Next, the operation of the real-time clock 10 configured as described above will be described with reference to FIG. First, when an electrical signal indicating that an event has occurred (for example, ON / OFF of a switch, etc.) is input to the event input terminal 22 from an event generation device (not shown), the event detection circuit 20 detects the signal, An event occurrence flag 24 is set. Specifically, as described above, the event occurrence flag 24 is changed from “0”, which is displayed when an electrical signal due to event occurrence is not detected, to “1”, which indicates that an electrical signal due to event occurrence has been detected. Perform the change process.

  In addition, the voltage of the current input from the power supply terminal 28 is compared with the reference voltage by the voltage comparison unit 30 in the voltage drop detection circuit 26. When the comparison determines that the applied voltage is lower than the reference voltage, the voltage drop detection circuit 26 sets the voltage drop flag 32. Specifically, as described above, the voltage drop flag 32 changes from “0”, which is indicated when the applied voltage is equal to or higher than the reference voltage, to “1”, which indicates that the applied voltage is lower than the reference voltage. Process to change.

  Since the event detection cycle 38 is input from the setting register 34 to the control circuit 42, it is determined whether or not an event occurrence is detected by the event detection circuit 20 according to this cycle (S10). Here, when the event occurrence flag 24 of the event detection circuit 20 is “0”, it is determined that the occurrence of the event has not been detected (in the case of No). When it is determined in the determination of whether or not an event has occurred that an event has not been detected, it is determined whether or not a decrease in applied voltage has been detected in order to determine whether the determination is correct (S20). Here, when the drop of the applied voltage is not detected (in the case of No), the process ends without performing the event data writing process, and waits until the timing of the next event detection cycle 38.

  On the other hand, when a decrease in the applied voltage is detected in S20 (in the case of Yes), the occurrence of the voltage decrease is shifted to event data writing processing as one additional data.

  If it is determined in S10 that an event has been detected (Yes), it is determined whether or not a decrease in applied voltage has been detected (S30). Here, even when a decrease in applied voltage is not detected (in the case of No) or when a decrease in applied voltage is detected (in the case of Yes), the process proceeds to the event data writing process. This is because whether or not a decrease in the applied voltage has been detected is for determining whether or not an event has been detected.

When shifting to the event data writing process, the control circuit 42 reads the current time stored in the timer circuit 18.
Thereafter, the control circuit 42 configures event data in which the additional data indicating the occurrence of the event and the voltage drop and the time data are combined, and the event data is written. In the event data write processing, first, event data is written to the address of the memory 40 (S40). Next, a process of writing event data to the data recording area in the memory 40 is performed (S50). Then, after the writing is completed, a process of adding “1” to the write address of the memory 40 is performed (S60). In order to write the event information to the memory 40, the event information may be written sequentially from the lower memory address to the upper memory address, or may be sequentially written from the upper memory address to the lower memory address. When writing is performed in order from the upper memory address to the lower memory address, “1” is subtracted from the write address.

  After the process of adding “1” to the write address of the memory 40 is finished, the process of writing the event information to the memory 40 is finished and the standby state is maintained until the next event detection cycle 38.

  According to the real-time clock 10 having such a configuration, a decrease in applied voltage for each event detection period 38 is also detected. Here, when the voltage (applied voltage) of the input current decreases, the reliability of the information (event occurrence flag 24) recorded in the register (not shown) of the event detection circuit 20 decreases. For this reason, with the above configuration, it is possible to improve the reliability of the determination as to whether or not the determination of the occurrence of an event is correct.

  Further, by recording the additional data together with the time data in the memory 40, the user can obtain information other than the time data when the event occurs. For example, if event-specific data is recorded as additional data, the type of event that has occurred can be specified.

  In addition, by recording the information when a drop in the applied voltage is detected as a single event, it is possible to confirm how long normal power supply has been made to the real-time clock 10, and the system The analysis accuracy when an error occurs is dramatically improved.

  In addition, when the vibrator 14 is a piezoelectric vibrator and crystal is used for the vibrating piece, it is possible to increase the accuracy of the event data recording time, and high-resolution event recording is possible.

  Next, a second embodiment according to the real-time clock of the present invention will be described with reference to FIG. Most configurations of the real-time clock according to the present embodiment are the same as those of the real-time clock 10 according to the first embodiment described above. Therefore, portions having the same function are denoted by reference numerals added with 100 in the drawings, and detailed description thereof is omitted. The difference between the real-time clock 110 according to the present embodiment and the real-time clock 10 according to the first embodiment is that the detection voltage by the voltage drop detection circuit 126 can be detected for each of a plurality of levels (voltage value ranges). It is in the point.

  Specifically, the voltage drop detection circuit 126 includes two voltage comparison units, and different threshold values (reference current voltages) are set for the two voltage comparison units. For example, as illustrated in FIG. 3, when the first voltage comparison unit 130 a and the second voltage comparison unit 130 b are provided, the threshold value (first threshold value) set in the first voltage comparison unit 130 a The lower limit value (for example, about 1.0 V to 1.5 V) of the current voltage for which the oscillation operation is guaranteed is set, and the threshold value (second threshold value) set in the second voltage comparison unit 130b is determined by the oscillation of the oscillator 112. What is necessary is just to set the oscillation stop voltage (for example, about 0.8V) which stops.

  When it is determined that the value of the voltage input to the first voltage comparison unit 130a is lower than the lower limit value of the operation guaranteed voltage, the non-operation guaranteed voltage flag 132a is set and input to the second voltage comparison unit 130b. When it is determined that the value of the applied voltage is lower than the oscillation stop voltage, the oscillation stop voltage flag 132b is set. That is, when the value of the input voltage is lower than the oscillation stop voltage, both the non-operation guaranteed voltage flag 132a and the oscillation stop voltage flag 132b are set.

  Specifically, as shown in FIG. 4, the current input from the power supply terminal 128 is input to both the first voltage comparison unit 130a and the second voltage comparison unit 130b, and the input current voltage is within the range of the operation guarantee voltage. If it is within the range, none of the flags is raised (F1 = 0, F2 = 0 in FIG. 4). On the other hand, when the input power supply voltage falls below the lower limit value of the operation guarantee voltage, it is determined that the input voltage falls below the threshold value of the first voltage comparison unit 130a, and the non-operation guarantee voltage flag 132a is set (in FIG. 4). F1 = 1). Furthermore, when the input voltage falls below the oscillation stop voltage, it is determined that the threshold value of the second voltage comparison unit 130b is also below, and the oscillation stop voltage flag 132b is set in addition to the non-operation guaranteed voltage flag 132a ( In FIG. 4, it is changed to F2 = 1).

  By making it possible to detect the voltage drop of the input current step by step in this way, it becomes possible to analyze the operating state of the real-time clock 110 in detail, and the information recorded as event data. It is also possible to determine the correctness in more detail.

  Next, a third embodiment according to the real-time clock of the present invention will be described with reference to FIG. Note that most of the configuration of the real-time clock according to the present embodiment is the same as that of the real-time clocks 10 and 110 according to the first and second embodiments described above. Therefore, portions having the same function are denoted by reference numerals obtained by adding 200 to the drawings, and detailed description thereof will be omitted.

  The difference between the real-time clock 210 according to this embodiment and the real-time clocks 10 and 110 according to the first and second embodiments is that an oscillation stop detection circuit 250 that determines the oscillation state of the oscillator 212 is provided. The oscillation stop detection circuit 250 picks up a signal output from the oscillation circuit 216 to the timer circuit 218, and determines whether or not the oscillation of the oscillator 212 is stopped based on the presence or absence of the signal output from the transmission circuit 216. It is.

  Therefore, when the signal input from the oscillation circuit 216 is interrupted to the oscillation stop detection circuit 250, it is determined that the oscillation of the oscillator 212 is stopped, and the oscillation stop detection flag 252 is set (changed from 0 to 1). To be configured).

  With such a configuration, even when the oscillation of the oscillator 212 stops due to factors other than a decrease in the power supply voltage, it is possible to verify the stop, that is, the failure of the time stored with the event. Thus, it is possible to improve the reliability of the recorded data and determine whether the recorded data is correct or not with high accuracy.

  In FIG. 5, the oscillation stop detection circuit 250 is provided in addition to the configuration of the real-time clock 110 shown in the second embodiment, but the real-time clock 110 according to the first embodiment is different from that shown in FIG. The oscillation stop detection circuit 250 may be provided, or the oscillation stop detection circuit 250 may be provided for a real-time clock that does not include the voltage drop detection circuits 26, 126, and 226.

  In the real-time clock according to the above-described embodiment, it is simply described that an event occurrence flag is set when an electric signal indicating that an event has occurred is detected by the event detection circuit. However, the real-time clock according to the present invention may be set so as to set an event occurrence flag by detecting the rising or falling of a pulse of an input electric signal and setting this as additional data. Specifically, the detection method setting data in event detection (whether the rising of the electrical signal is detected or the falling is detected) is recorded in the setting register, and this is used as a command value for the event detection circuit, When recording time data, it may be recorded as additional data whether the detected signal is at the rising edge or the falling edge.

  According to such a configuration, information on whether the rising or falling of the electrical signal is detected is added to the recorded time data. For this reason, even if the contents of the setting register are rewritten and the recorded time data can no longer be read from the setting register whether it is caused by the rise or fall of the electrical signal, Based on the information added to the recorded time data, it becomes possible to know whether the signal was at the rising edge or at the falling edge. That is, by recording the setting of the event input terminal as additional information, the user can read the setting value from the recorded data without knowing the original setting value (setting value of the setting register). is there.

  Further, in each of the above embodiments, it is described that the number of event input terminals is one and additional information is attached to the electric signal input thereto. In this case, it is necessary to add specific information to the electric signal itself input to the event input terminal in advance. However, with the following configuration, the electric signal for each event is the same. In addition, event-specific information can be added to the signal output to the control circuit. That is, a plurality of event input terminals are provided, and individual event generation devices (not shown) are connected to each. Then, a port number assigned to each input terminal is added to the electric signal input to the event input terminal, and this is output to the control circuit as event-specific information, and the additional information is configured. Data. Even in such a configuration, it can be regarded as a real-time clock according to the present invention.

  10... Real time clock 12... Oscillator 14... Oscillator 16... Oscillator circuit 18. , 34... Setting register, 40... Memory, 42... Control circuit, 46.

Claims (7)

A real-time clock that outputs time data,
An event detection circuit for detecting that an event detection signal is input from the outside;
A timing circuit that generates the time data based on a signal output from the oscillation circuit;
Memory,
Control that records event data having additional data indicating an operation state of the real-time clock and the time data generated by the timing circuit in the memory when the event detection circuit detects the input of the event detection signal Circuit,
Real-time clock characterized by comprising. The real-time clock according to claim 1,
A voltage drop detection circuit that detects a drop in the power supply voltage applied to the power supply terminal,
The real time clock characterized in that the additional data includes voltage drop information which is information indicating a drop in the power supply voltage detected by the voltage drop detection circuit. The real-time clock according to claim 2,
The voltage drop detection circuit includes a first voltage comparison unit that detects that the power supply voltage is lower than a first threshold,
The voltage drop detection information indicates that when the event detection circuit detects the input of the event detection signal, the first voltage comparison unit of the voltage drop detection circuit indicates that the power supply voltage is below the first threshold value. A real-time clock characterized by including information indicating whether or not is detected. The real-time clock according to claim 3,
The voltage drop detection circuit further includes a second voltage comparison unit that detects that the power supply voltage is lower than a second threshold set lower than the first threshold.
The voltage drop detection information includes information indicating whether or not the second voltage comparison unit of the voltage drop detection circuit detects that the power supply voltage is lower than the second threshold. Real time clock. The real-time clock according to any one of claims 1 to 4,
An oscillation stop detection circuit for detecting that the oscillation circuit has stopped oscillating;
The real-time clock, wherein the additional data includes oscillation stop information indicating whether or not the oscillation stop detection circuit detects the oscillation stop. A real-time clock according to any one of claims 2 to 5,
A setting register capable of setting one of a rising detection mode for detecting a rising of a voltage waveform of the event detection signal and a falling detection mode for detecting a falling;
The additional data includes detection information indicating which of the rising detection mode and the falling detection mode is set in the setting register when the event detection circuit detects the input of the event detection signal. Real-time clock characterized by that. The real-time clock according to any one of claims 2 to 6,
Provide a plurality of terminals for inputting the event detection signal,
When the event detection circuit detects an input of the event detection signal, the control circuit includes the additional data, the time data, and the port number of the terminal to which the event detection signal is input. Is recorded in the memory.

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