JP5725284B2 - Integrated circuit, integrated circuit device, rotation detection device - Google Patents

Description

  The present invention relates to an integrated circuit, an integrated circuit device, a rotation detection device, and the like.

  There is known a technique for suppressing power consumption by switching a plurality of sampling periods with a detection device or the like. For example, in Patent Document 1, in an electronic water meter that is an example of a detection device, the rotation of a rotating body based on a flow rate is compared with a normal sampling result, and the sampling cycle is shortened only when it is determined to be abnormal. Therefore, power consumption can be reduced.

JP-A-8-94401

  Detection devices such as electronic water meters generally include a sensor and a processor that processes its output. The processor is, for example, a CPU or a microcontroller (hereinafter referred to as MCU). Patent Document 1 includes a sensor (rotation detector) and a CPU, but only the sensor can achieve low power consumption by the disclosed method. Therefore, it has been difficult to further reduce power consumption including the CPU.

  The present invention has been made in view of such problems. According to some aspects of the present invention, it is effective to intermittently drive the processor by outputting the detected rotation as an interrupt signal and to change the sampling period of the sensor according to the rotation stop period. In addition, an integrated circuit or the like that suppresses power consumption of the detection system can be provided.

(1) The present invention is an integrated circuit that detects rotation using a first pulse and a second pulse output from a sensor, and is based on the first pulse and the second pulse. At least one of a first circuit that performs rotation detection and a second circuit that performs reverse rotation detection; and a third circuit that counts a rotation stop period based on the first pulse and the second pulse. The first circuit outputs a first interrupt signal, the second circuit outputs a second interrupt signal, and the third circuit outputs a signal indicating the rotation stop period. To do.

  According to the present invention, an external processor is intermittently driven by outputting the detected rotation as an interrupt signal (first interrupt signal, second interrupt signal). Therefore, while the interrupt signal is not generated, the processor may be in a sleep state, for example, so that the power consumption of the system can be reduced.

  Further, according to the present invention, for example, the processor selects the sampling period of the sensor corresponding to the rotation stop period based on the signal indicating the rotation stop period from the third circuit. Therefore, the power consumed by the sensor can be suppressed, and the power consumption of the system can be reduced.

  In the present invention, since the first pulse and the second pulse output from the sensor are used, highly accurate rotation detection can be performed.

  The signal indicating the rotation stop period of the third circuit may be a count value indicating the rotation stop period or a pulse signal indicating that the rotation stop period has continued for a predetermined period. At this time, the pulse signal may be output as an interrupt signal.

(2) This integrated circuit may include an oscillation circuit, and the third circuit may count based on a clock output from the oscillation circuit.

  According to the present invention, it is possible to accurately measure the rotation stop period based on the clock output from the oscillation circuit by including the oscillation circuit. By selecting an appropriate sensor sampling period based on an accurate rotation stop period, it is possible to effectively reduce power consumption.

(3) In this integrated circuit, when the count value reaches a predetermined value, the third circuit may output a third interrupt signal as a signal indicating the rotation stop period.

  According to the present invention, the third circuit outputs a third interrupt signal as a signal indicating the rotation stop period. This eliminates the need for the processor to periodically read a count value indicating the rotation stop period, for example. While the interrupt signal is not generated, the processor may be in a sleep state, for example, so that the power consumption of the system can be reduced.

(4) In this integrated circuit, a power supply control signal for controlling the power supply of the sensor may be output.

  According to the present invention, it is possible to effectively reduce the power consumption by controlling the power source of the sensor by the power supply control signal. At this time, the power supply control signal can be selected by a signal indicating the rotation stop period from the third circuit. Therefore, it is possible to effectively suppress the power consumption of the sensor portion having a relatively large power consumption according to the situation.

(5) The present invention is an integrated circuit device including any of the integrated circuits described above.

  According to the present invention, the integrated circuit can be miniaturized by making the integrated circuit into a single chip, and the applicable range can be widened.

(6) The present invention includes the integrated circuit according to any one of the above and an MCU that receives an interrupt signal from the integrated circuit, and the MCU calculates a rotation amount in a first operation mode, In the operation mode, the rotation detection device operates with lower power consumption than the first operation mode and transitions from the second operation mode to the first operation mode when the interrupt signal is received.

  The MCU (Micro Controller Unit) is, for example, a processor and includes a memory such as a ROM and a RAM and peripheral functions related to an interface. For this reason, there is a possibility that the power consumption increases when the mode is always the normal operation mode (first operation mode). The MCU of the present invention has a mode (second operation mode) in which power consumption is made smaller than that during normal operation, such as a power save mode. The normal operation is, for example, calculation of the number of rotations performed by the rotation detection device.

  According to the present invention, when the interrupt signal is received from the integrated circuit, the second operation mode is changed to the first operation mode. The MCU is in the second operation mode while no interrupt occurs, and can reduce power consumption.

The block diagram of the integrated circuit of 1st Embodiment. An integrated circuit device including the integrated circuit of the first embodiment and a rotation detection device. FIG. 3A is a waveform diagram for explaining an interrupt. FIG. 3B is an enlarged view of a part of FIG. FIG. 4A is a flowchart of the first interrupt process. FIG. 4B is a flowchart of the second interrupt process. FIG. 5A is a flowchart of third interrupt processing. FIG. 5B is a flowchart of timer interrupt processing. The flowchart of a modification. FIG. 7A is a top view of a flow path in which the rotation detection device is installed. FIG. 7B is a partial cross-sectional view thereof. 8A to 8C are diagrams illustrating a magnetic sensor.

1. First Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 to 5B. Further, the operation of the rotation detection device will be described with reference to FIGS. 7 (A) to 8 (C). Below, operation | movement of a rotation detection apparatus is demonstrated first, and the integrated circuit etc. of 1st Embodiment are demonstrated after that.

1.1. Operation of Rotation Detection Device The operation of the rotation detection device will be described with reference to FIGS. 7 (A) to 8 (C). FIG. 7A is a top view of a flow path in which the rotation detection device is installed, and FIG. 7B shows a partial cross-sectional view thereof. In FIG. 7A, the magnetic sensor is not shown.

  In the rotation detection device, the amount to be measured (measured amount) is replaced with the rotation speed, and the rotation speed is detected by, for example, a magnetic sensor and an electric signal is output. The electric signal is processed by, for example, an MCU to obtain a measured amount. The amount to be measured may be a flow rate of a liquid such as water, or may be pressure, temperature, illuminance, or the like. Below, the rotation detection apparatus which measures the flow volume of a liquid is demonstrated. For example, the liquid is water, which can be applied to a water meter.

  In FIG. 7A, the impeller 100 is installed in the liquid flow path 104. When the liquid flows in the direction of the arrow X1, the impeller 100 rotates clockwise as indicated by the arrow X2. The liquid flow rate can be determined by measuring the number of rotations. Here, a magnet 102 is attached to the shaft of the impeller 100, and the magnetism changes as the impeller 100 rotates.

  FIG. 7B is a cross-sectional view of the liquid flow path 104 in FIG. Near the impeller 100, a magnetic sensor 106 is attached to the substrate 108 and installed. At this time, the magnetic sensor 106 is not in contact with the impeller 100. The magnetic sensor 106 detects magnetism that is changed by the magnet 102 when the impeller 100 rotates. Then, an electric signal is output based on the detection result, and for example, an MCU (not shown) attached to the substrate 108 receives the signal and calculates the rotation speed. The MCU also calculates the liquid flow rate based on the number of rotations.

  Here, the rotation of the impeller 100 clockwise is called forward rotation, and the rotation of the impeller 100 counterclockwise is called reverse rotation. The reverse rotation indicates that the liquid flows in the direction opposite to the arrow X1. The magnetic sensor 106 may be able to detect reverse rotation. At this time, the MCU may receive an electrical signal indicating reverse rotation and adjust the rotational speed and the liquid flow rate.

  FIG. 8A shows how the magnetic sensor 106 in FIG. 7B detects magnetism. The magnetic sensor 106 includes a Wheatstone bridge type magnetic detection circuit 70 </ b> A configured by magnetoresistive elements R <b> 1 to R <b> 4 whose electric resistance changes due to magnetism.

For example, in FIG. 8A, it is assumed that magnetism is generated across the magnetoresistive elements R2 and R3 (X3 in FIG. 8A). At this time, for example, the resistance values of the magnetoresistive elements R2 and R3 change from “r” to “r + Δr”, but the resistance values of the magnetoresistive elements R1 and R4 remain “r”. As a result, the signal A + potential rises, the signal A- is the potential decreases, the signal SR _A output from the comparator 72A is at a low level (hereinafter referred to as "0"). Conversely, when the magnetic is generated across the magneto-resistive element R1 and R4, the signal SR _A becomes high level (hereinafter referred to as "1").

Here, when the impeller 100 rotates, the magnetism generated by the magnet 102 also rotates. That is, θ in FIG. 8A changes with time. For example, the signal SR _A varies according to the value of θ as the upper waveform diagram of FIG. 8 (C). The magnetic sensor 106, the magnetic detection circuit 70A, it outputs a signal SR _A corresponding to the rotation of the magnetic.

  However, the magnetic detection circuit 70A performs the same detection even if the magnetic direction is reversed by 180 °. That is, the magnetic detection circuit 70A cannot distinguish even the direction of magnetism. Therefore, it is not possible to distinguish between forward rotation and reverse rotation with only one magnetic detection circuit 70A. Therefore, the magnetic sensor 106 needs to include a plurality of magnetic detection circuits.

  FIG. 8B shows the magnetic detection circuit 70A and the magnetic detection circuit 70B installed with a narrow angle of 45 °. The magnetoresistive elements R5 to R8 of the magnetic detection circuit 70B constitute a Wheatstone bridge in the same manner as the magnetic detection circuit 70A.

Magnetic detection circuit 70B is to detect the same magnetic magnetic detection circuit 70A, the signal SR _B outputted from the comparator 72B is signal SR _A and phase are different. The narrow angle of 45 °, as in the lower waveform diagram of FIG. 8 (C), the results in which the signal SR _B whose phases are shifted are output from the signal SR _A.

Therefore, it is possible to distinguish between forward rotation and reverse rotation by combining the signal SR _A and the signal SR _B. For example 1 bit signal SR _A, generates a sensor sampling value a 2-bit signal and the second bit signals SR _B. At this time, if the rotation is positive, the sensor sampling value changes in the order of 1, 0, 2, 3, 1, 0, 2, 3,... As shown in FIG. If the rotation is reverse, the sensor sampling value changes in the order of 3, 2, 0, 1, 3, 2, 0, 1,. The magnetic sensor 106 can distinguish between forward rotation and reverse rotation by changing a 2-bit sensor sampling value. And as FIG.8 (C) shows, the change of a sensor sampling value respond | corresponds to rotation of 45 degrees.

  Note that although the two magnetic detection circuits can distinguish between forward rotation and reverse rotation, the magnetic sensor 106 may include three or more magnetic detection circuits. At this time, the rotation detection accuracy can be further increased.

1.2. Configuration of Integrated Circuit of this Embodiment FIG. 1 is a block diagram of an integrated circuit 10 of this embodiment. The integrated circuit 10 includes a first circuit 11, a second circuit 12, and a third circuit 13. Further, as in the present embodiment, the integrated circuit 10 may include a timer 21, a power supply control circuit 22, and an oscillation circuit 23. Note that the integrated circuit 10 of this embodiment is used as a part of a rotation detection device that measures the flow rate of water, and assumes that there is an MCU that counts the number of positive rotations.

The integrated circuit 10 receives the first sampling value 200 </ b> A and the second sampling value 200 </ b> B, and these signals are input to the first circuit 11, the second circuit 12, and the third circuit 13. The first sampling value 200A and the second sampling value 200B correspond to the signals SR _A and SR _B , respectively (see FIGS. 8A to 8B). The sensor sampling value is generated by the first sampling value 200A and the second sampling value 200B. From the change in sensor sampling value, the presence or absence of rotation can be determined, and it is possible to distinguish between forward rotation and reverse rotation.

  The first circuit 11 performs forward rotation detection (forward rotation detection), and the second circuit 12 performs reverse rotation detection (reverse rotation detection). When it is determined that there is a normal rotation by detecting the normal rotation, the first interrupt signal 211 is output from the first circuit 11. If it is determined by the reverse rotation detection that the reverse rotation has occurred, the second interrupt signal 212 is output from the second circuit 12. By outputting the detected rotation as an interrupt signal, the MCU can be intermittently driven, so that the power consumption of the system including the integrated circuit 10 can be reduced.

  The direction in which water flows in a water meter or the like is determined. Therefore, the direction in which the impeller rotates due to the flow of water when there is no abnormality is defined as the direction of forward rotation (see FIG. 7A). The reverse rotation occurs when, for example, the connection is wrong in the installation work or when an abnormality occurs. When reverse rotation occurs, for example, the MCU may or may not adjust to reduce the normal rotation speed. Further, when reverse rotation occurs, for example, the MCU may notify the abnormality by display or the like.

  The third circuit 13 outputs a signal indicating the rotation stop period. The rotation stop period is a period during which both the first sampling value 200A and the second sampling value 200B, which are outputs from the sensor (not shown), remain unchanged. The third circuit 13 counts the rotation stop period. The counter (rotation stop period counter) of the third circuit 13 may be an up counter as in this embodiment or a down counter.

  The third circuit 13 outputs a third interrupt signal 213 that changes when the rotation stop period continues for a predetermined period as a signal indicating the rotation stop period. Therefore, for example, it is not necessary for the MCU to periodically read the count value indicating the rotation stop period. In addition, since the MCU can be intermittently driven as described above, the power consumption of the system including the integrated circuit 10 can be reduced. Note that the MCU may receive the third interrupt signal 213 to set the sensor sampling period longer than the current time, thereby further reducing the power consumption of the system.

  The integrated circuit 10 of this embodiment also includes an oscillation circuit 23, a timer 21, and a power supply control circuit 22. The oscillation circuit 23 may be connected to a vibrator 74 (for example, a crystal vibrator) to generate an oscillation loop and output the clock 223. At this time, the third circuit 13 may count the rotation stop period by the clock 223. By using the clock 223 of the oscillation circuit 23 included in the integrated circuit 10, information such as the frequency can be grasped, and the rotation stop period can be accurately measured.

  For example, the timer 21 may output a timer interrupt signal 221 periodically generated at an interval set by a control signal 201 from the MCU. For example, the MCU can update the display periodically by the timer interrupt signal 221.

  The power supply control circuit 22 selects a cycle of a pulse signal that turns on a power source of a sensor or the like by a control signal 202 from the MCU, for example. Sensors and the like operate when the power is on to sample data. That is, the power supply control circuit 22 determines the sampling period. The power supply control signal 222 output from the power supply control circuit 22 may be a pulse signal having this sampling period.

  For example, the MCU can determine that the rotation is stopped by the third interrupt signal 213. At this time, selection of a mode (low speed mode) in which the sampling period is 1/16 second may be instructed to the power supply control circuit 22 by the control signal 202. For example, the MCU can determine that water is flowing by the first interrupt signal 211. At this time, the power supply control circuit 22 may be instructed by the control signal 202 to change from the low speed mode to a mode (high speed mode) in which the sampling period is 1/1024 seconds. By selecting an appropriate sensor sampling period, it is possible to effectively reduce power consumption.

  Note that the clock 223 from the oscillation circuit 23 may be supplied to a module outside the figure. Further, although the clock 223 is supplied to blocks other than the third circuit 13 in the integrated circuit 10, it is not shown in FIG.

  In this embodiment, the first interrupt signal 211, the second interrupt signal 212, the third interrupt signal 213, and the timer interrupt signal 221 are all cleared by an interrupt clear signal to clear the interrupt flag. Shall. Interrupt clear signals exist corresponding to these interrupt signals, but are not shown in FIG.

1.3. Integrated Circuit Device, Rotation Detection Device FIG. 2 shows an integrated circuit device 2 including the integrated circuit 10 of this embodiment and the rotation detection device 1. In addition, the same number and code | symbol are attached | subjected about the same element as FIG. 1, FIG.7 (A)-FIG.8 (C), and description is abbreviate | omitted.

  As shown in FIG. 2, the integrated circuit 10 of this embodiment may be used as a part of the rotation detection device 1. At this time, the integrated circuit 10 may be integrated into one chip as the integrated circuit device 2 together with the magnetic detection circuits 70A and 70B, the comparators 72A and 72B, and the switch 76. The magnetic detection circuits 70A and 70B and the comparators 72A and 72B correspond to the magnetic sensor 106 (see FIG. 7B) .Hereinafter, the magnetic detection circuits 70A and 70B and the comparators 72A and 72B are collectively expressed as sensors.

  The integrated circuit device 2 controls the power supply of the sensor by the power supply control signal 222. For example, the switch 76 is turned on only when the power supply control signal 222 is 1, and sampling is performed by the sensor. Other than that, the sensor does not consume power, so power consumption can be reduced.

  In the rotation detection device 1, the MCU 3 may select the sampling period by specifying the low speed mode or the high speed mode by the control signal 202.

  The integrated circuit device 2 outputs interrupt signals 211, 212, 213, and 221 to the MCU 3. The MCU 3 may operate in the second operation mode that consumes less power than the normal operation mode (first operation mode) except when receiving an interrupt signal. Thereby, low power consumption can be achieved.

  When receiving an interrupt signal, the MCU 3 first enters the first operation mode. The MCU 3 may have a positive rotation number counter, for example, and may increment and decrement when receiving the first interrupt signal and the second interrupt signal, respectively. The value of the positive rotation number counter corresponds to the flow rate of water. Further, when the third interrupt signal is received, the control signal 202 may be changed. Then, when the timer interrupt signal 221 is received, the water flow rate data displayed on the display device (not shown) may be updated.

  In the integrated circuit device 2, the comparators 72A and 72B may have a hysteresis function to prevent erroneous detection. The hysteresis function may be switched on and off by a control signal (not shown). Further, the integrated circuit device 2 may be formed as a single chip including the MCU 3.

1.4. Waveform Diagram FIGS. 3A to 3B are waveform diagrams of the integrated circuit 10. In addition, the same number and code | symbol are attached | subjected to the same element as FIGS. 1-2, FIG.7 (A)-FIG.8 (C), and description is abbreviate | omitted.

  FIG. 3A shows the generation timing of the interrupt signal. The sensor sampling value is a 2-bit value in which the first sampling value 200A is the first bit and the second sampling value 200B is the second bit.

  As described above, the power supply control signal 222 indicates the sampling period because it gives the timing to turn on the sensor. The sampling period of the present embodiment includes a low speed mode for reducing power consumption when rotation is stopped and a high speed mode for performing accurate detection.

In the case of low-speed mode, the sampling period is longer T _S than the high-speed mode. For example, _{T S} is 1/16 seconds. In the case of the high speed mode, the sampling period is _TF . For example, _TF is 1/1024 seconds.

In the example of FIG. 3 (A), an initial low-speed mode, it is changed to the first time point t ₀ to a high speed mode the interrupt signal 211 occurs first of which represents a positive rotation. Then, the changed predetermined between, the low-speed mode at the time t ₈ the third interrupt signal 213 indicating that the rotation stop period continues occurs. The low speed mode and the high speed mode are designated by the control signal 202 by the MCU 3 (see FIG. 2) that has received the interrupt signal.

Until time _{t 4,} the sensor sampling values it can be seen that the forward rotation is changing with 2,3,1,0,2,3,1 (see FIG. 8 (C)). Therefore, the first interrupt signal 211 is generated with a change in the sensor sampling value (time t ₀ , t ₁ , t ₂ , t ₃ ). Upon receiving the first interrupt signal 211 once, the MCU 3 increments the positive rotation number counter on the assumption that 45 ° forward rotation has occurred (see FIG. 8C).

Until time _{t 4} after the time _{t 8,} the sensor sampling values it can be seen that the reverse rotation is changing with 1,3,2,0,1,3 (see FIG. 8 (C)). Therefore, the second interrupt signal 212 is generated with the change in the sensor sampling value (time t ₄ , t ₅ , t ₆ , t ₇ ). Upon receiving the second interrupt signal 212 once, the MCU 3 decrements the normal rotation number counter on the assumption that 45 ° reverse rotation has occurred (see FIG. 8C). Further, the MCU 3 may be set so as not to change the positive rotation number counter depending on the second interrupt signal 212.

At time t _8, the third interrupt signal 213 is generated, MCU 3 may determine the rotation stopping period for a predetermined, followed by that with. Therefore, the MCU 3 sets the sampling cycle to the low-speed mode, lengthens the sampling interval of the sensor, and suppresses power consumption.

Incidentally, the timer interrupt signal 221 may be independently generated from other interrupt signals at a predetermined time interval T _C. In this case, MCU 3 may update the display every time interval _{T C.} Incidentally, MCU 3 may change the interval _{T C} by the control signal 201 times.

FIG. 3B is an enlarged view of part of FIG. 3A in which necessary signals are added and some signals are deleted. The first sampling value 200A and the second sampling value 200B are the first bit and the second bit of the sensor sampling value, respectively. These signals change at the falling edge of the power supply control signal 222, that is, the timing at which sampling data is determined. Pulse width _{T A} of the power supply control signal 222 is 5μs, for example. In the example of FIG. 3 (B), the power is supplied to the sensor, for example, from the time _{t 10} by 5 .mu.s.

The rotation stop period counter is included in the third circuit 13 (see FIG. 1), and counts the rotation stop period in synchronization with the clock 223. The rotation stop period counter is reset by the first interrupt signal 211 and the second interrupt signal 212 (time t ₁₁ ). The rotation stop period counter may be reset by the MCU 3 that has received the first interrupt signal 211 or the second interrupt signal 212. Note that the first interrupt signal 211 and the second interrupt signal 212 may be generated several clocks after the sensor sampling value changes (after 4 clocks in FIG. 3B).

Each of the interrupt signals is cleared by an interrupt signal clear signal. In FIG. 3B, after the first interrupt signal 211 is generated, the MCU 3 generates a first interrupt clear signal (time t ₁₂ ). Then, for example, the first interrupt clear signal is cleared after one clock (time t ₁₃ ).

The time _t 14 _{~t 17} is a repeat of states at each time _t 10 _{~t 13} omitted. At time t ₁₈ , the third interruption signal 213 is generated because the rotation stop period counter has reached a predetermined value 511.

1.5. Flowchart The integrated circuit 10 of the present embodiment is used as a part of a rotation detection device that measures the flow rate of water, such as a water meter, for example. This is assumed (see FIG. 2). The MCU 3 controls the integrated circuit 10. Here, the control when the MCU 3 receives an interrupt signal will be described with reference to the flowcharts of FIGS. 4 (A) to 5 (B). In the present embodiment, it is assumed that the interrupt signals are independent of each other, and the interrupt processing of the MCU 3 is performed independently for each of the interrupt signals.

  FIG. 4A shows a first interrupt process that is executed when the MCU 3 receives the first interrupt signal 211. First, the MCU 3 generates a first interrupt clear signal and performs a clear process (S11). Then, assuming that 45 ° forward rotation has occurred (see FIG. 8C), the forward rotation number counter is incremented (S12). Then, the sampling cycle is set to a high-speed mode for performing accurate detection (S13). In the high speed mode, sampling is performed every 1/1024 seconds. In this embodiment, only the low speed mode and the high speed mode exist. Therefore, the mode does not change when the sampling period is already set to the high-speed mode.

  However, three or more modes may be prepared as another embodiment. In this case, the mode is switched to a mode in which the sampling cycle becomes shorter. For example, there are first to seventh modes in which the sampling period is 1/1024 seconds, 1/512 seconds, 1/256 seconds, 1/128 seconds, 1/64 seconds, 1/32 seconds, and 1/16 seconds. And For example, when the current state is the fourth mode (1/128 seconds) and the first interrupt signal 211 is received, the mode may be shifted to the fifth mode (1/64 seconds). Further, when the first interrupt signal 211 is received, the mode may be shifted to the sixth mode (1/32 seconds). At this time, by switching the sampling cycle step by step, it is possible to avoid a sudden change in setting and perform more accurate flow rate measurement.

  FIG. 4B shows a second interrupt process that is executed when the MCU 3 receives the second interrupt signal 212. First, the MCU 3 generates a second interrupt clear signal and performs a clear process (S21). At this time, it can be determined that 45 ° reverse rotation has occurred, but the processing may be divided depending on the setting. If the setting is to be reflected in the forward rotation counter when reverse rotation occurs (S22Y), the forward rotation counter is decremented (S23). However, if the settings are different (S22N), the positive rotation number counter is not changed. Thereafter, as in the first interrupt process, the sampling period may be set to a high-speed mode in which accurate detection is performed (S24).

  In addition, since it is judged that it is abnormal when reverse rotation occurs, the step (S24) of setting the sampling cycle to the high speed mode may be omitted. Further, when step S24 is executed and three or more modes are prepared, the mode may be switched to a mode in which the sampling cycle is further shortened.

  FIG. 5A shows a third interrupt process that is executed when the MCU 3 receives the third interrupt signal 213. First, the MCU 3 generates a third interrupt clear signal and performs a clear process (S31). Then, the operation of the rotation stop period counter is stopped (S32). In order to reduce power consumption, the sampling cycle is set to the low speed mode (S33).

  When three or more modes are prepared, the mode may be switched to a mode in which the sampling period is longer. At this time, it is not necessary to stop the operation of the rotation stop period counter until the mode with the longest sampling cycle is reached (S32).

  FIG. 5B shows timer interrupt processing that is executed when the MCU 3 receives the timer interrupt signal 221. First, the MCU 3 generates a timer interrupt clear signal and performs a clear process (S41). Then, based on the value of the positive rotation number counter, the positive rotation number is displayed on the display device (S42). Since the data is updated at regular intervals, the user can always get the latest information. The displayed data may be the flow rate of water obtained by calculation instead of the normal rotation speed.

  Thus, the MCU 3 only needs to execute the interrupt process when an interrupt occurs. For example, it is assumed that the MCU 3 has a normal operation mode (first operation mode) and a mode (second operation mode) in which power consumption is made smaller than that during normal operation. At this time, the MCU may be in the second operation mode as long as no interrupt occurs, and power consumption can be kept low.

  Further, the MCU 3 sets the sampling cycle to the low speed mode in the third interrupt processing. In other words, the power consumption of the system can be reduced by selecting the sampling period of the sensor according to the state where the rotation is stopped.

  Note that the integrated circuit of this embodiment can detect rotation with high accuracy of 45 ° by inputting two pulse signals output from the sensor. At this time, since only two sets of magnetic detection circuits and comparators are required as sensors, the area does not increase significantly even in an integrated circuit device including the sensors, for example.

2. Modification A modification of the present embodiment will be described with reference to FIG. The same elements as those in FIGS. 1 to 5B and FIGS. 7A to 8C are denoted by the same reference numerals and description thereof is omitted.

  The interrupt process of the MCU 3 in the modified example is a process in which the first to third interrupt processes are incorporated into the timer interrupt process with a high occurrence frequency.

  As shown in FIG. 6, first, it is confirmed whether or not the timer interrupt signal 221 is generated (S1). If the timer interrupt signal 221 is not generated, nothing is executed (S1N). When the timer interrupt signal 221 is generated (S1Y), the clear process is performed (S41). Note that step S41 is the same as FIG.

  Thereafter, whether or not the first interrupt signal 211, the second interrupt signal 212, and the third interrupt signal 213 are generated is confirmed (S2, S4, S6). If these interrupt signals are not generated, nothing is executed (S2N, S4N, S6N). If they occur (S2Y, S4Y, S6Y), the first interrupt process S3 and the second interrupt process are performed. S5 and third interrupt processing S7 are executed.

  Here, the first interrupt process S3 corresponds to the process of FIG. 4A, and the second interrupt process S5 corresponds to the process of FIG. 4B. The third interrupt process S7 corresponds to the process of FIG.

  Thereafter, the positive rotation speed is displayed on the display device (S42). Step S42 is the same as FIG.

  This modification can be applied even when the first to third interrupt signals are obtained only as interrupt flags mapped to, for example, a register. Therefore, it may be used when the number of interrupt input ports of the MCU is limited.

  The present invention is not limited to these exemplifications, and includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects).

  For example, although the present embodiment and the modification have been described using the magnetic sensor, the pressure sensor, the illuminance sensor, and the temperature sensor may be used instead of the magnetic sensor. For example, these sensors can be replaced by corresponding to the forward and reverse rotations of pressure, illuminance, and temperature, respectively.

  In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 ... Rotation detection apparatus, 2 ... Integrated circuit apparatus, 3 ... MCU, 10 ... Integrated circuit, 11 ... 1st circuit, 12 ... 2nd circuit, 13 ... 3rd circuit, 21 ... Timer, 22 ... Power supply Control circuit 23 ... Oscillation circuit 70A ... Magnetic detection circuit 70B ... Magnetic detection circuit 72A ... Comparator 72B ... Comparator 74 ... Vibrator 76 ... Switch 100 ... Impeller 102 ... Magnet 104 ... Flow path, 106 ... magnetic sensor, 108 ... substrate, 200A ... first sampling value, 200B ... second sampling value, 201 ... control signal, 202 ... control signal, 211 ... first interrupt signal, 212 ... second 213 ... third interrupt signal, 221 ... timer interrupt signal, 222 ... power supply control signal, 223 ... clock

Claims (7)

An integrated circuit that detects rotation using a first pulse and a second pulse output from a sensor,
At least one of a first circuit that performs forward rotation detection and a second circuit that performs reverse rotation detection based on the first pulse and the second pulse;
Anda third circuit for counting based on the clock of the first based rather rotation stop period in the second pulse and pulses,
The first circuit outputs a first interrupt signal to a processor external to the integrated circuit ;
The second circuit outputs a second interrupt signal to the processor ;
The third circuit is an integrated circuit that outputs a signal indicating the rotation stop period to the processor . The integrated circuit of claim 1, wherein
Including an oscillation circuit,
The clock is
The output Ru current product circuit from the oscillator circuit. The integrated circuit according to claim 1,
The third circuit includes:
An integrated circuit that outputs a third interrupt signal as a signal indicating the rotation stop period when the count value reaches a predetermined value. The integrated circuit according to any one of claims 1 to 3,
An integrated circuit for outputting a power supply control signal for controlling power supply of the sensor.   An integrated circuit device comprising the integrated circuit according to claim 1. An integrated circuit according to any one of claims 1 to 4;
As the processor, including the rotation detecting apparatus, and a MCU for receiving at least one of said first interrupt signal and the second interrupt signal from the integrated circuit. The rotation detection device according to claim 6,
The MCU
Calculating the amount of rotation in the first operation mode;
Operate in the second operation mode with lower power consumption than in the first operation mode;
A rotation detection device that transitions from the second operation mode to the first operation mode when the first interrupt signal or the second interrupt signal is received.