JP2022064701A - Rotary encoder rotation detection method - Google Patents

Abstract

To provide a rotary encoder rotation detection method that suppresses a computation load of a control device such as a CPU and the like, and prevents wrong detection of rotation detection due to chattering and the like.SOLUTION: A rotary encoder rotation detection method according to the present invention is configured to: detect an interruption based on a change in a signal level of an A-phase or a B-phase; and start interruption processing as to one phase having the interruption detected. The starting interruption processing for the one phase has: a signal level acquisition step of acquiring a signal level of other phase different from the one phase; an interruption detection flag acquisition step of acquiring presence or absence of an interruption detection flag of the other phase; and a rotation detection step of performing rotation detection of a rotary encoder when the signal level of the A-phase and the signal level of the B-phase are identical, and the interruption detection flag of the other phase is present.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for detecting rotation of a rotary encoder. In particular, the present invention relates to a rotary encoder rotation detection method capable of preventing erroneous detection of the rotation direction of the rotary encoder due to chattering or the like and suppressing the calculation load of the CPU for rotation detection.

Conventionally, a rotary encoder has been adopted for the purpose of detecting the rotation of a dial or a motor.

There are optical and magnetic / electric induction methods for the rotation detection method of the rotary encoder, and the method suitable for the application and usage environment of the device equipped with the rotary encoder is adopted.

For example, an optical rotary encoder is composed of a light emitting element such as an LED, a light receiving element such as a photodiode, and a rotating slit disk provided with slits at equal pitches in the circumferential direction.

In the optical rotary encoder, the light emitting element and the light receiving element are arranged to face each other, and the light from the light emitting element is arranged so as to be received by the light receiving element. The rotary slit disk is arranged so as to be sandwiched between the light emitting element and the light receiving element, and rotates according to the rotation of the rotating mechanical element.

The light from the light emitting element passes through or is blocked from the slit provided in the rotary slit disk depending on the rotational position of the rotating rotary slit disk. As a result, the light receiving element receives the light from the light emitting element, and the signal level output from the light receiving element changes depending on the position of the slit. The signal level output from the light receiving element is processed by a peripheral circuit and output as a square wave.

Two phases (A phase and B phase) rectangular waves for identifying the rotation direction are output from the optical rotary encoder. The A-phase and B-phase square waves are output with a predetermined phase (for example, 1/4 period) shifted from each other. In order to output a square wave of A phase and B phase which are shifted by a predetermined phase from each other, for example, light receiving elements of A phase and B phase may be provided respectively, and these may be arranged so as to be offset from each other.

FIG. 1 shows an example of A-phase and B-phase square waves output from an optical rotary encoder that are offset by a quarter period from each other. The rotation direction of the rotary encoder is identified based on the relationship between the A-phase and B-phase square waves at the time of identification.

For example, in the method for identifying the rotation direction based on the relationship between the A-phase and B-phase square waves in FIG. 1, the A-phase is when the signal level of the B-phase drops from H (high level) to L (low level). When the signal level of is H, it is identified as having rotated one step clockwise, and conversely, when the signal level of the A phase drops from H to L, the signal level of the B phase is H. Is identified as having rotated one step counterclockwise.

By the way, the change (falling or rising) of the A-phase and B-phase signal levels that determine the time point for identifying the rotation direction of the optical rotary encoder is also generated by the noise transmitted to the signal level output from the optical rotary encoder. There is a risk of When the noise is a plurality of electrical pulses, a phenomenon called chattering occurs in which the signal levels of the A phase and the B phase vibrate violently in a short time. These noises may lead to malfunction of the rotational direction identification of the optical rotary encoder.

Patent Document 1 (Japanese Unexamined Patent Publication No. 6-137892) discloses a method for reading a rotary encoder that can prevent a malfunction of reading in the rotation direction even if chattering occurs at the signal level of the A phase and the B phase. Has been done.

In the method of reading the rotary encoder of Patent Document 1, the level state of the A-phase / B-phase signal read in a predetermined sampling cycle is compared with the level state of the A-phase / B-phase signal read before one sampling cycle. A sub-counter that increases / decreases the count value is provided, and if the transition of the level state of the A-phase / B-phase signal is due to the normal rotation of the rotary encoder, the count value of the sub-counter is increased / decreased according to the rotation direction. , The rotation direction of the rotary encoder is identified based on the count value of the sub-counter at the time when the level state of the A-phase / B-phase signal is in a predetermined state.

Japanese Unexamined Patent Publication No. 6-137892

However, the method for reading a rotary encoder disclosed in Patent Document 1 has the following problem, although it can prevent a malfunction of reading in the rotation direction due to chattering.

In Patent Document 1, in order to detect the rotation of a rotary encoder rotating at high speed without being affected by chattering, a predetermined sampling cycle for monitoring a sub-counter must be shortened. Further, even when the rotary encoder is not actually rotating, the sub-counter must be constantly monitored with a shorter sampling cycle in order to cope with the rotation detection of the rotary encoder rotating at high speed. Therefore, the reading method of the rotary encoder disclosed in Patent Document 1 imposes a large computational load on a control device such as a CPU.

Furthermore, when the rotary encoder rotates at high speed in a predetermined sampling cycle or longer, the monitoring in the predetermined sampling cycle by the sub counter cannot keep up with the speed of change in the signal level of the A phase and B phase, and the sub counter counts. Since the value cannot be increased or decreased correctly, the rotation direction of the rotary encoder may be erroneously identified.

In order to solve the above problems, the rotation detection method of the rotary encoder of the first invention according to the present invention is a rotary encoder that detects rotation based on two signal levels of A phase and B phase which are out of phase with each other. In the rotation detection method, an interrupt is detected by a change in the signal level of the A phase or the B phase, interrupt processing is started for one phase that has detected the interrupt, and the interrupt processing started for the one phase is described above. A signal level acquisition step for acquiring the signal level of the other phase different from one phase, an interrupt detection flag acquisition step for acquiring the presence / absence of the interrupt detection flag of the other phase, and a signal level of the A phase and the B phase. It is characterized by having a rotation detection step for detecting the rotation of the rotary encoder when the signal levels are the same and the interrupt detection flag of the other phase is present.

The rotation detection method of the rotary encoder of the second invention according to the present invention detects an interrupt by a change in the signal level of the A phase or the B phase, and in the interrupt processing for one of the detected interrupts. If there is an interrupt detection flag for the other phase that is different from the one acquired in the interrupt detection flag acquisition step, an interrupt detection flag clear step for clearing the interrupt detection flag for the other phase is further added. It is characterized by having.

The rotation detection method of the rotary encoder of the third invention according to the present invention detects an interrupt by a change in the signal level of the A phase or the B phase, and in the interrupt processing for one of the detected interrupts, the interrupt is started. When the signal level of the one phase in which the interrupt is detected and the signal level of the other phase different from the one acquired in the signal level acquisition step are different, the interrupt detection flag of the one phase is set. It is characterized by further having an interrupt detection flag set step to be present.

The rotation detection method of the rotary encoder according to the fourth aspect of the present invention detects an interrupt due to a change in the signal level of the A phase or the B phase, and in interrupt processing for one of the detected interrupts. The rotation direction detected by the rotation detection step is opposite to the rotation direction detected by the rotation detection step of the interrupt processing of the other phase, which is different from the one phase.

The rotation detection method of the rotary encoder according to the present invention prevents the rotation detection from malfunctioning due to chattering or the like, suppresses the calculation load of the control device such as the CPU even during high-speed rotation, and suppresses the rotation detection malfunction. Can be prevented.

It is a figure which shows the rectangular wave of A phase and B phase output from a rotary encoder. It is a block diagram which shows the rotary encoder in the digital camera of this Example. It is a figure which shows the rectangular wave of A phase and B phase output from a rotary encoder. It is a figure explaining the principle of the rotation detection method of the rotary encoder of this Example. It is a flowchart which shows the rotation detection method of a rotary encoder. It is a flowchart which shows A phase interrupt processing. It is a flowchart which shows the B phase interrupt processing. It is a figure which shows the case where noise occurs in the signal level of A phase.

Hereinafter, examples of a digital camera that employs the rotation detection method of the rotary encoder according to the present invention will be described.

Conventionally, a digital camera is equipped with an operation dial for setting shooting conditions, menu items, and the like. By operating the operation dial, the user can set shooting modes such as auto, aperture priority, and shutter speed priority, and set values such as aperture value, shutter speed, and exposure compensation, as well as menus and playback. You can manipulate the image.

When the operation dial is operated by the user, the digital camera must accurately detect the rotation of the operation dial and operate as the user intends. In addition, even if the operation dial is not operated by the user, it must be on standby so that rotation detection can be performed at any time. A rotary encoder is used to detect the rotation of the operation dial.

FIG. 2 is a configuration diagram showing a rotary encoder in the digital camera of this embodiment. In FIG. 2, 10 is an operation dial, 20 is a rotary encoder, 30 is a peripheral circuit, 40 is a control device, 41 is an interrupt detection unit, 42 is an A-phase interrupt processing unit, 43 is a B-phase interrupt processing unit, and 44 is a storage unit. Is shown.

The operation dial 10 is rotated by a user who intends to set setting values of shooting conditions, menu operations, and the like.

The rotary encoder 20 is composed of a rotating shaft, a rotating slit disk, a light emitting element such as an LED, and a light receiving element such as a photodiode.

The rotation shaft is connected to the operation dial and rotates according to the rotation of the operation dial. The rotary slit disk is fixed to the rotary shaft and rotates according to the rotation of the rotary shaft. The rotary slit disk is provided with slits at equal pitches in the circumferential direction. The light emitting element and the light receiving element are arranged so as to sandwich the rotating slit disk, and the light from the light emitting element transmitted through the slit of the rotating slit disk is received by the light receiving element. The light from the light emitting element passes through the slit or is blocked according to the rotation of the rotating slit disk. The light receiving element outputs an output signal of the light received from the light emitting element according to the presence or absence of a slit in the rotating slit disk. Two light receiving elements are provided so as to be able to acquire output signals of A phase and B phase which are out of phase by 1/4 period from each other.

The peripheral circuit 30 amplifies the A-phase and B-phase output signals output from the rotary encoder 20 and converts them into a square wave composed of signal levels binarized to high level (H) and low level (L). Or

As shown in FIG. 3, the output signal output from the peripheral circuit 30 is a square wave of A phase and B phase which are out of phase by 1/4 period from each other. H and L signal levels appear alternately in the rectangular wave normally output by the rotation of the rotary encoder 20.

The rotation direction of the rotary encoder 20 can be identified based on the A-phase and B-phase square waves output from the peripheral circuit 30. For example, if the A-phase and B-phase square waves are constantly monitored and the B-phase signal level is H at the time when the A-phase signal level falls, the normal rotation (CW) direction is obtained. It can be identified as the rotation direction, and when the signal level of the B phase is L, it can be identified as the rotation direction in the inversion (CCW) direction.

The control device 40 detects the rotation of the rotary encoder 20 from the A-phase and B-phase output signals output from the peripheral circuit 30. The control device 40 is, for example, a CPU or a control block thereof.

The control device 40 includes an interrupt detection unit 41, an A-phase interrupt processing unit 42, a B-phase interrupt processing unit 43, and a storage unit 44.

The interrupt detection unit 41 detects that there is a change in the signal level in either the A-phase or B-phase square wave output from the peripheral circuit 30, and detects the A-phase or B-phase interrupt. In this embodiment, an interrupt is detected by detecting that one of the output signals of the A phase and the B phase has a fall.

The A-phase interrupt processing unit 42 and the B-phase interrupt processing unit 43 perform interrupt processing for the A-phase or B-phase in which an interrupt is detected by the interrupt detection unit 41, and detect the rotation of the rotary encoder 20. The contents of the interrupt processing for the A phase or the B phase will be described later.

The storage unit 44 temporarily holds an interrupt detection flag or the like indicating the presence / absence of an A-phase / B-phase interrupt detected by the interrupt detection unit 41 inside the control device 40. The role of the interrupt detection flag in interrupt processing will be described later.

Next, the flow of the rotation detection method of the rotary encoder in the digital camera of this embodiment will be described. As shown in FIG. 4, in the rotation detection method of the rotary encoder of the present embodiment, interrupt processing is performed for one of the phases that have detected the interrupt by detecting the interrupt of the A phase and the B phase, and both the A phase and the B phase are performed. Rotation detection is performed when an interrupt is generated in and the signal level of the other phase is the same as the signal level of the one phase. As a result, when detecting the rotation of the rotary encoder, it is possible to confirm the occurrence of interrupts for both the A phase and the B phase, so that more reliable rotation detection that is not affected by noise due to chattering or the like can be performed. can.

FIG. 5 is a flowchart showing a rotation detection method of the rotary encoder in the digital camera of this embodiment. Each step of the flowchart of FIG. 5 will be described.

First, when the interrupt detection unit 41 of the control device 40 detects an interrupt for either the A phase or the B phase, interrupt processing is performed for one of the A phase and the B phase in the interrupt processing start step S101. To start. The interrupt is detected because there is a drop in either the A-phase or B-phase signal level in the output signal output from the peripheral circuit 30. The falling edge of the signal level is the change of the signal level from H to L in the output signal output as a square wave.

Then, either the A-phase interrupt process S102 or the B-phase interrupt process S103 started in the interrupt process start step S101 is performed. When the A-phase interrupt process S102 or the B-phase interrupt process S103 is completed, the flowchart of FIG. 5 is terminated.

Next, the A-phase interrupt process S102 will be described with reference to the flowchart of FIG.

First, in the B phase signal level acquisition step S201, the signal level of the B phase, which is the other phase of the A phase, is acquired. In this embodiment, the signal level of the B phase at the time immediately after the interrupt where the signal level of the A phase has a fall is acquired. As a result, it is possible to prevent noise from being generated in the B phase during the A phase interrupt processing S102 and erroneous rotation detection.

Next, in the B-phase interrupt detection flag acquisition step S202, the B-phase interrupt detection flag temporarily held in the storage unit 44 of the control device 40 is acquired, and the presence or absence of the B-phase interrupt is determined. The B-phase interrupt detection flag is a flag for indicating the presence / absence of a B-phase interrupt before the A-phase interrupt processing.

When it is determined in the B-phase interrupt detection flag acquisition step S202 that there is a B-phase interrupt, the B-phase detection flag is cleared in the B-phase detection flag clear step S203. That is, the B-phase detection flag is cleared and the B-phase interrupt is eliminated. As a result, it is possible to prevent the history of B-phase interrupts before this after the A-phase interrupt processing S102 from being carried over.

If the history of B-phase interrupts before this is carried over after the A-phase interrupt process S102, if a continuous fall occurs at the signal level of the A phase due to chattering or the like, the A-phase is all dropped. There is a possibility that rotation detection will be performed in the interrupt process S102. By clearing the B-phase interrupt detection flag when it is present, rotation detection in the A-phase interrupt process S102 occurs even if the signal level of the A-phase continuously drops after the A-phase interrupt process S102. Can be done only once.

Next, in the B phase signal level determination step S204, it is determined whether or not the signal level of the B phase acquired in the B phase signal level acquisition step S201 is H. Here, since the A-phase interrupt process S102 is started by detecting the falling edge of the A-phase signal level as an A-phase interrupt, the A-phase signal level in the A-phase interrupt process S102 is L. That is, when it is determined in the B phase signal level determination step S204 that the signal level of the B phase is H, it is equivalent to the fact that the signal levels of the A phase and the B phase are different, and the signal level of the B phase is L. When it is determined that the signal level is the same, it is equivalent to that the signal levels of the A phase and the B phase are the same.

When it is determined in the B phase signal level determination step S204 that the signal level of the B phase is L, rotation detection is performed assuming that the signal level is rotated one step in the normal rotation (CW) direction in the CW rotation detection step S205. The rotation amount (rotation angle) of the operation dial 10 per step is set in the control device 40 in advance, and the actual rotation amount (rotation angle) of the operation dial 10 is obtained by multiplying this by the number of steps detected for rotation. You can ask.

In the A-phase interrupt process S102, rotation detection is performed only when a B-phase interrupt occurs before this, so rotation detection of the rotary encoder 20 is performed only in the forward rotation (CW) direction.

When rotation detection is not performed in the A-phase interrupt process S102, the A-phase interrupt detection flag is set in the A-phase interrupt detection flag setting steps S206 and S208. That is, the A-phase detection flag is set to enable the A-phase interrupt. The A-phase interrupt detection flag is temporarily held in the storage unit 44 of the control device 40.

When it is determined that the B-phase interrupt detection flag is present in the B-phase interrupt detection flag acquisition step S202 and the B-phase signal level is determined to be H in the B-phase signal level determination step S204, the A-phase interrupt detection flag is determined. In the set step S206, the A-phase interrupt detection flag is set. This is mainly because the B-phase interrupt detection flag is set in the B-phase interrupt process S103 when the rotary encoder 20 rotates in the forward rotation (CW) direction, and then immediately inverted (when it rotates in the inversion (CCW) direction (CCW). This is to enable rotation detection in the CCW) direction.

When it is determined in the B-phase interrupt detection flag acquisition step S202 that the B-phase interrupt detection flag is absent, and in the B-phase signal level determination step S207 it is determined that the B-phase signal level is H, the A-phase interrupt detection flag is determined. In the set step S208, the A-phase interrupt detection flag is set. This is mainly so that the rotation detection in the inversion (CCW) direction can be performed by setting the A-phase interrupt detection flag when the rotary encoder 20 rotates in the inversion (CCW) direction and leaving the history of the A-phase interrupt. To do.

If it is determined in the B-phase interrupt detection flag acquisition step S202 that the B-phase interrupt detection flag is absent, and if it is determined in the B-phase signal level determination step S207 that the B-phase signal level is L, the A-phase interrupt is interrupted. It is determined that the drop in the signal level of the A phase that triggered the start of the process S102 is due to noise, for example, and the A phase interrupt detection flag is not set. Since it is determined that there is no B-phase interrupt detection flag, naturally, the rotation detection of the rotary encoder 20 in the forward rotation (CW) direction is not performed.

After the A-phase interrupt process S102 is completed, the interrupt detection unit 41 of the control device 40 waits until an interrupt is detected for either the A-phase or the B-phase.

Next, the B-phase interrupt process S103 will be described with reference to the flowchart of FIG.

First, in the A phase signal level acquisition step S301, the signal level of the A phase, which is the other phase of the B phase, is acquired. In this embodiment, the signal level of the A phase at the time immediately after the interrupt where the signal level of the B phase has a fall is acquired. As a result, it is possible to prevent noise from being generated in the A phase during the B phase interrupt processing S103 and erroneous rotation detection.

Next, in the A-phase interrupt detection flag acquisition step S302, the A-phase interrupt detection flag temporarily held in the storage unit 44 of the control device 40 is acquired, and the presence or absence of the A-phase interrupt is determined. The A-phase interrupt detection flag is a flag for indicating the presence / absence of an A-phase interrupt before the B-phase interrupt processing.

When it is determined in the A phase interrupt detection flag acquisition step S302 that there is an A phase interrupt, the A phase detection flag is cleared in the A phase detection flag clear step S303. That is, the A-phase detection flag is cleared and there is no A-phase interrupt. As a result, it is possible not to carry over the history of the A-phase interrupt before the B-phase interrupt process S103.

If the history of the interrupts of the A phase before this is carried over after the B phase interrupt process S103, when the signal level of the B phase continuously falls due to chattering or the like, the B phase for all the falls. There is a possibility that rotation detection will be performed in the interrupt process S103. By clearing the A-phase interrupt detection flag when it is present, even if the B-phase signal level drops continuously after the B-phase interrupt process S103, rotation detection in the B-phase interrupt process S103 occurs. Can be done only once.

Next, in the A phase signal level determination step S304, it is determined whether or not the signal level of the A phase acquired in the A phase signal level acquisition step S301 is H. Here, since the B-phase interrupt process S103 is started by detecting the falling edge of the B-phase signal level as a B-phase interrupt, the B-phase signal level in the B-phase interrupt process S103 is L. That is, when it is determined in the A phase signal level determination step S304 that the signal level of the A phase is H, it is equivalent to the fact that the signal levels of the B phase and the A phase are different, and the signal level of the A phase is L. When it is determined that the signal level is the same, it is equivalent to that the signal levels of the B phase and the A phase are the same.

When it is determined in the A phase signal level determination step S304 that the signal level of the A phase is L, rotation detection is performed assuming that the signal level is rotated by one step in the inversion (CCW) direction in the CCW rotation detection step S305. The rotation amount (rotation angle) of the operation dial 10 per step is set in the control device 40 in advance, and the actual rotation amount (rotation angle) of the operation dial 10 is obtained by multiplying this by the number of steps detected for rotation. You can ask.

In the B-phase interrupt process S103, rotation detection is performed only when there is an A-phase interrupt before this, so rotation detection of the rotary encoder 20 is performed only in the inversion (CCW) direction.

When rotation detection is not performed in the B-phase interrupt process S103, the B-phase interrupt detection flag is set in the B-phase interrupt detection flag setting steps S306 and S308. That is, the B-phase detection flag is set to enable the B-phase interrupt. The B-phase interrupt detection flag is temporarily held in the storage unit 44 of the control device 40.

When it is determined in the A-phase interrupt detection flag acquisition step S302 that the A-phase interrupt detection flag is present and the A-phase signal level is determined to be H in the A-phase signal level determination step S304, the B-phase interrupt detection flag is determined. In the set step S306, the B-phase interrupt detection flag is set. This is mainly because the A-phase interrupt detection flag is set in the A-phase interrupt process S103 when the rotary encoder 20 is rotated in the reverse (CCW) direction, and then the rotary encoder 20 is immediately rotated in the forward rotation (CW) direction. This is to enable rotation detection in the (CW) direction.

When it is determined in the A-phase interrupt detection flag acquisition step S302 that the A-phase interrupt detection flag is absent, and in the A-phase signal level determination step S307, it is determined that the A-phase signal level is H, the B-phase interrupt detection flag is determined. In the set step S308, the B-phase interrupt detection flag is set. This can mainly detect rotation in the forward rotation (CW) direction by setting a B-phase interrupt detection flag when the rotary encoder 20 rotates in the forward rotation (CW) direction and leaving a history of B-phase interrupts. To do so.

If it is determined in the A-phase interrupt detection flag acquisition step S302 that the A-phase interrupt detection flag is absent, and if it is determined in the A-phase signal level determination step S307 that the A-phase signal level is L, the B-phase interrupt is interrupted. It is determined that the drop in the signal level of the B phase that triggered the start of the process S103 is due to noise, for example, and the B phase interrupt detection flag is not set. Since it is determined that there is no A-phase interrupt detection flag, naturally, the rotation of the rotary encoder 20 in the inversion (CCW) direction is not detected.

After the B-phase interrupt process S103 is completed, the interrupt detection unit 41 of the control device 40 waits until an interrupt is detected for either the B-phase or the A-phase.

Next, in the rotation detection method of the rotary encoder of this embodiment, a state of preventing erroneous detection of rotation detection due to chattering or the like will be described.

FIG. 8 shows an example in which noise due to chattering or the like is generated at the signal level of the A phase when the operation dial 10 is rotated in the forward rotation (CW) direction. As described in the flow of the rotation detection method of the rotary encoder in the digital camera of this embodiment, the falling edge of the signal level of the A phase starts the A phase interrupt process S102 for detecting the rotation in the forward rotation (CW) direction. It will be a trigger.

In FIG. 8, after the falling D1 of the signal level of the B phase is followed by the falling D2 of the signal level of the A phase and the rotation detection in the normal rotation (CW) direction is performed, the noise N1 is the signal of the A phase. When it occurs at the level, the B-phase interrupt detection flag is cleared and the B-phase signal level is L. Therefore, the noise N1 is judged as noise, and neither the A-phase interrupt detection flag is set nor the rotation detection is performed. ..

Further, in FIG. 8, when noise N2 or noise N3 is generated at the signal level of the A phase, the B phase interrupt detection flag is cleared and the B phase signal level is H, so that the A phase interrupt detection flag is set. Although it is set, rotation detection in the forward rotation (CW) direction is not performed. Since the A-phase interrupt detection flag is used for rotation detection in the inversion (CCW) direction, it does not affect rotation detection in the forward rotation (CW) direction.

Further, in FIG. 8, when the noise N4 is generated at the signal level of the A phase, the noise N4 is generated before the falling D2 of the signal level of the A phase, so that the falling of the signal level of the A phase due to the noise N4 is caused. Rotation detection in the forward rotation (CW) direction is performed as an interrupt. However, since the B-phase interrupt detection flag is cleared at that time, even if a falling D2 occurs after the noise N4, the rotation detection is performed only once, which affects the rotation detection in the normal rotation (CW) direction. Do not give. Further, even when the noise N4 is generated a plurality of times in succession, the B-phase interrupt detection flag is cleared when the first noise N4 is generated, so that the rotation detection in the forward rotation (CW) direction is not affected.

In this embodiment, the fall of the signal level of the A phase and the B phase is used as an interrupt to start the interrupt processing of the A phase and the B phase, but this is the trigger for starting the interrupt processing of the A phase and the B phase. The same effect as that of the present invention can be obtained as a rising edge.

As described above, according to the rotation detection method of the rotary encoder of the present invention, it is not necessary to increase the sampling frequency of the control device such as the CPU in order to support the rotation detection of the rotary encoder rotating at high speed. Further, even when the rotary encoder is not rotating, it is not necessary to constantly monitor the signal levels of the A phase and the B phase by a control device such as a CPU at a predetermined cycle. As a result, the calculation load of a control device such as a CPU can be suppressed.

Even if noise occurs at the signal levels of A phase and B phase due to chattering, etc., it rotates only when there is an interrupt in both A phase and B phase and the signal levels of A phase and B phase are the same. Since the detection is performed, there is no possibility that a malfunction will occur in the rotation detection of the rotary encoder.

10 Operation dial 20 Rotary encoder 30 Peripheral circuit 40 Control device 41 Interrupt detection unit 42 A-phase interrupt processing unit 43 B-phase interrupt processing unit 44 Storage unit

Claims (4)

In the rotation detection method of a rotary encoder that detects rotation based on two signal levels, A phase and B phase, which are out of phase with each other.
An interrupt is detected by a change in the signal level of the A phase or the B phase, and interrupt processing for one of the detected phases is started.
The interrupt processing started for one of the phases
A signal level acquisition step for acquiring the signal level of the other phase different from the one phase,
The interrupt detection flag acquisition step for acquiring the presence / absence of the interrupt detection flag in the other phase, and
It is characterized by having a rotation detection step for detecting the rotation of the rotary encoder when the signal level of the A phase and the signal level of the B phase are the same and the interrupt detection flag of the other phase is present. How to detect the rotation of the rotary encoder. In the interrupt processing for one phase in which an interrupt is detected by a change in the signal level of the A phase or the B phase and the started interrupt is detected.
If there is an interrupt detection flag of the other phase different from the one phase acquired in the interrupt detection flag acquisition step, an interrupt detection flag clear step for clearing the interrupt detection flag of the other phase is further added. The rotation detection method for a rotary encoder according to claim 1, wherein the rotary encoder has. In the interrupt processing for one phase in which an interrupt is detected by a change in the signal level of the A phase or the B phase and the started interrupt is detected.
If the signal level of the one phase that detected the interrupt is different from the signal level of the other phase that is different from the one phase acquired in the signal level acquisition step, the interrupt detection flag of the one phase is set. The rotation detection method for a rotary encoder according to claim 1 or 2, further comprising an interrupt detection flag set step to be present. In the interrupt processing for one phase in which an interrupt is detected by a change in the signal level of the A phase or the B phase and the started interrupt is detected.
Claim 1 is characterized in that the rotation direction detected in the rotation detection step is opposite to the rotation direction detected in the rotation detection step of the interrupt processing of the other phase different from the one phase. The method for detecting rotation of a rotary encoder according to any one of claims 3.

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