JP2018074621A - Motor controller and motor drive system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control circuit and a motor drive system, which can suppress an increase in the number of terminals.SOLUTION: A motor controller comprises: a first common terminal; a selection terminal to which a selection signal is inputted; a mode signal generation section for generating a first mode signal which designates an exciting mode of a motor on the basis of an input signal from the first common terminal when the selection signal is a first value; a serial communication section for performing serial communication with an external device by using the input signal from the first common terminal when the selection signal is a second value; a target position generation section for generating a target position of the motor on the basis of the first mode signal; and a vector control section for generating a control signal that controls the motor on the basis of the target position.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a motor control device and a motor drive system.

  Stepping motors are widely used as positioning motors. In recent years, vector control capable of fine torque control has been used as a stepping motor control method with a reduction in the price of 32-bit microcomputers. In vector control, various parameters need to be set. As a parameter setting method, a method is used in which a register is provided in the motor control device, and the parameter is written to the register by serial communication from an external device.

  However, in the conventional method, it is necessary to provide a terminal for serial communication in the motor control device. When the number of terminals increases, there is a problem that the area of a chip (LSI: Large Scale Integration) increases and the manufacturing cost of the motor control device increases.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a motor control circuit and a motor drive system that can suppress an increase in terminals.

  A motor control device according to an embodiment includes a first common terminal, a selection terminal to which a selection signal is input, and, when the selection signal is a first value, a motor based on an input signal from the first common terminal. A mode signal generation unit for generating a first mode signal for designating an excitation mode of the device and, when the selection signal is a second value, serial communication with an external device is performed using an input signal from the first shared terminal A serial communication unit; a target position generation unit that generates a target position of the motor based on the first mode signal; a vector control unit that generates a control signal for controlling the motor based on the target position; Is provided.

  According to each embodiment of the present invention, it is possible to provide a motor control circuit and a motor drive system that can suppress an increase in terminals.

The figure which shows an example of a structure of a motor drive system. The figure which shows an example of a structure of the motor control part 11 which concerns on 1st Embodiment. The flowchart which shows an example of the process by a mode signal generation part and a serial communication part. The flowchart which shows an example of the process by a target position production | generation part, a vector control part, and a PWM signal generation part. The figure which shows an example of a structure of the motor control part 11 which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, regarding the description of the specification and the drawings according to each embodiment, constituent elements having substantially the same functional configuration are denoted by the same reference numerals and overlapping description is omitted.

<First Embodiment>
The motor drive system according to the first embodiment will be described with reference to FIGS. First, the configuration of the motor drive system will be described. FIG. 1 is a diagram illustrating an example of a configuration of a motor drive system. The motor drive system of FIG. 1 includes a motor M and a motor control device 1.

  The motor M is a motor capable of vector control, and is driven by the motor control device 1. The motor M is, for example, a permanent magnet type, a variable reluctance type, or a hybrid type stepping motor, but is not limited thereto. In the example of FIG. 1, the motor M is a two-phase (A-phase and B-phase) motor, but may be a three-phase motor or a five-phase motor.

  The motor control device 1 supplies power to the motor M and drives (rotates) the motor M in accordance with a signal input from an external device. The external device is an arbitrary device capable of serial communication with the motor control device 1 and capable of inputting various signals to be described later to the motor control device 1. The external device is a PC (Personal Computer) or a control board connected to the PC, but is not limited thereto. The motor control device 1 includes a motor control unit 11 and a driver unit 12.

  The motor control unit 11 performs vector control of the motor M based on an input signal from the outside. Specifically, the motor control unit 11 generates a PWM (Pulse Width Modulation) signal so that the rotor of the motor M is at a predetermined position (angle). In the example of FIG. 1, it is assumed that the motor control unit 11 is configured by a one-chip microcomputer, but the motor control unit 11 may be configured by a plurality of microcomputers. The motor controller 11 will be described in detail later.

  The driver unit 12 receives the PWM signal generated by the motor control unit 11, applies a voltage to each phase (A phase and B phase) of the motor M and supplies power to the motor M according to the input PWM signal. . The motor M is driven by the power supplied from the driver unit 12. The driver unit 12 is configured by an inverter, for example. In the example of FIG. 1, it is assumed that the driver unit 12 is configured by a one-chip IC (Integrated Circuit), but the motor control unit 11 may be configured by a plurality of ICs. The driver unit 12 may be configured integrally with the motor control unit 11.

  Next, the configuration of the motor control unit 11 according to the present embodiment will be described. FIG. 2 is a diagram illustrating an example of the configuration of the motor control unit 11 according to the present embodiment. The motor control unit 11 in FIG. 2 includes terminals Tc, Td, Ts, T1 to T3, Tout, a mode signal generation unit 111, a serial communication unit 112, a target position generation unit 113, a register 114, and a vector control unit. 115 and a PWM signal generation unit 116.

  The configuration from the mode signal generation unit 111 to the PWM signal generation unit 116 may be configured by dedicated hardware, or may be configured by software (program) executed by a microcomputer. As hardware, an FPGA (Field Programmable Gate Array), an ASIC (Application Specified IC), a DSP (Digital Signal Processor), and the like can be used. The motor control unit 11 may be provided with a driver unit 12.

  The terminal Tc is an input terminal to which the clock CLK is input. The clock CLK is a pulse signal and is used for generating a target position of the motor M. The clock CLK is input to the target position generator 113.

  The terminal Td is an input terminal to which the direction signal DIR is input. The direction signal DIR is a signal that designates the rotation direction of the motor M, and the two values correspond to the positive and negative rotation directions, respectively. The direction signal DIR is input to the target position generation unit 113.

  The terminal Ts (selection terminal) is an input terminal to which the selection signal SEL is input. The selection signal SEL is a signal for designating whether the terminals T1 to T3 are used for generating the mode signal MODE1 (first mode signal) or for serial communication. It corresponds to each of two applications. Hereinafter, the value 0 (first value) of the selection signal SEL indicates that the terminals T1 to T3 are used for generation of the mode signal MODE1, and the value 1 (second value) indicates that the terminals T1 to T3 are serial. It shall be used for communication. The selection signal SEL is input to the mode signal generation unit 111 and the serial communication unit 112, respectively.

  The terminal T1 (first shared terminal) is an input terminal shared for generating the mode signal MODE1 and serial communication. Specifically, the terminal T1 receives the mode signal mode1 when the value of the selection signal SEL is 0, and receives the serial reception data RXD when the value of the selection signal SEL is 1. An input signal (mode signal mode1 or serial reception data RXD) from the terminal T1 is input to the mode signal generation unit 111 and the serial communication unit 112, respectively. The mode signal mode1 is used to generate the mode signal MODE1. The serial reception data RXD is data received from an external device by serial communication.

  The terminal T2 (second shared terminal) is an input / output terminal shared for generating the mode signal MODE1 and serial communication. Specifically, the terminal T2 receives the mode signal mode2 when the value of the selection signal SEL is 0, and outputs the serial transmission data TXD when the value of the selection signal SEL is 1. An input signal (mode signal mode2) from the terminal T2 is input to the mode signal generation unit 111 and the serial communication unit 112, respectively. The mode signal mode2 is used for generating the mode signal MODE1. The serial transmission data TXD is data transmitted to an external device by serial communication.

  The terminal T3 (third shared terminal) is an input terminal shared for generating the mode signal MODE1 and serial communication. Specifically, the terminal T3 receives the mode signal mode3 when the value of the selection signal SEL is 0, and receives the clock SCK when the value of the selection signal SEL is 1. An input signal (mode signal mode3 or clock SCK) from the terminal T3 is input to the mode signal generation unit 111 and the serial communication unit 112, respectively. The mode signal mode3 is used for generating the mode signal MODE1. The clock SCK is a pulse signal and is used for sampling a serial signal.

  The terminal Tout is an output terminal that outputs a PWM signal. The PWM signal output from the terminal Tout is input to the driver unit 12.

  When the value of the selection signal SEL is 0, the mode signal generation unit 111 generates the mode signal MODE1 based on the input signals (mode signal mode1, mode signal mode2, and mode signal mode3) from the terminals T1 to T3. The mode signal MODE1 is a signal that designates the excitation mode of the motor M. A corresponding excitation mode is preset for each value of the mode signal MODE1. The settable excitation modes include one-phase excitation, two-phase excitation, 1-2 phase excitation, W1-2 phase excitation, and 2W1-2 phase excitation. In other words, when specifying the excitation mode of the motor M, the external device performs motor control on the selection signal SEL having a value of 0 and the mode signal mode1, the mode signal mode2, and the mode signal mode3 having values corresponding to the specified excitation mode. Input to device 1.

  When the mode signal MODE1 is a 3-bit signal, the mode signal MODE1 can take eight values from 000 to 111. When the excitation mode corresponding to each value of the mode signal MODE1 is set, one excitation mode can be designated from among the eight excitation modes by the mode signal MODE1. Note that the number of bits of the mode signal MODE1 is arbitrary.

  In addition, each value of the mode signal may be set to the operation state of the corresponding motor control device 1 instead of the excitation mode. The settable operating states include a standby state and a test state. The standby state is an operation state in which the operation of at least a part of the configuration of the motor control device 1 is stopped. In the standby state, the power consumption of the motor control device 1 is reduced. The test state is an operation state for testing the control of the motor M by the motor control device 1.

  The mode signal mode1, the mode signal mode2, and the mode signal mode3 may be any signals that can generate the mode signal MODE1 as described above. Here, consider a case where the mode signal MODE1 is a 3-bit signal. In this case, the mode signal mode1, the mode signal mode2, and the mode signal mode3 may be signals indicating the first bit, the second bit, and the third bit of the mode signal MODE1, respectively.

  The first bit, the second bit, and the third bit are the first bit (LSB: Least Significant Bit), the second bit, and the third bit (MSB: Most Significant Bit) of the mode signal MODE1, respectively. Also good. Also, the first bit, the second bit, and the third bit may be the first bit (MSB), the second bit, and the third bit (LSB) of the mode signal MODE1, respectively.

  In this case, the mode signal generation unit 111 can generate the mode signal MODE1 by arranging the values of the mode signal mode1, the mode signal mode2, and the mode signal mode3 in a predetermined order.

  Note that the mode signal mode1, the mode signal mode2, and the mode signal mode3 are not limited to the above example. For example, when the mode signal MODE1 is a 2-bit signal, any one of the mode signal mode1, the mode signal mode2, and the mode signal mode3 may not be used to generate the mode signal MODE1. For example, when the mode signal MODE1 is a signal of 4 bits or more, a terminal for inputting a signal indicating the fourth bit of the mode signal MODE1 to the motor control unit 11 may be provided.

  Further, when the value of the selection signal SEL changes from 0 to 1, the mode signal generation unit 111 holds the mode signal MODE1 immediately before the change. This is because when the value of the selection signal SEL is 1, a signal for serial communication (such as serial reception data RXD) is input from the terminals T1 to T3. When the mode signal MODE1 is generated based on this input signal, an unexpected mode signal MODE1 is generated. Since the mode signal generation unit 111 holds the mode signal MODE1 immediately before the value of the selection signal SEL changes from 0 to 1, generation of the unexpected mode signal MODE1 as described above can be suppressed.

  When the value of the selection signal SEL is 1, the serial communication unit 112 performs serial communication with an external device using input / output signals (serial reception data RXD, serial transmission data TXD, and clock SCK) from the terminals T1 to T3. I do. In other words, when the external device performs serial communication with the motor control device 1, the selection signal SEL having a value of 1 and the serial reception data RXD are input to the motor control device 1. In addition, the external device receives serial transmission data TXD from the motor control device 1. Any standard such as RS-232 or RS-423 can be used as a serial communication standard.

  Specifically, the serial communication unit 112 samples the serial reception data RXD input from the terminal T1 according to the clock SCK, and writes the obtained data to the register 114. The data written to the register 114 includes parameters used for vector control. The serial communication unit 112 preferably increases the impedance of the terminal T1 when receiving the serial reception data RXD.

  Also, the serial communication unit 112 reads data from the register 114 in response to a request from the external device, generates serial transmission data TXD based on the read data, and generates the generated serial transmission data TXD from the terminal T2 as a clock SCK. According to the output. The data read from the register 114 includes parameters used for vector control.

  The target position generator 113 generates a target position for the motor M based on the clock CLK, the direction signal DIR, and the mode signal MODE1. The target position of the motor M corresponds to the target value (command value) of the electrical angle of the rotor of the motor M.

  Specifically, the target position generation unit 113 detects the edge of the input clock CLK. The edge to be detected may be a rising edge, a falling edge, or both a rising edge and a falling edge.

  The target position generator 113 increases or decreases the target position by a predetermined change amount each time an edge is detected. Whether to increase or decrease the target position depends on the rotation direction specified by the direction signal DIR. The target position generation unit 113 increases the target position when the direction signal DIR specifies a positive rotation direction, and decreases the target position when the direction signal DIR specifies a negative rotation direction.

  The amount of change in the target position that is increased or decreased each time an edge is detected is determined by the excitation mode designated by the mode signal MODE1. For example, when the excitation mode is 1-2 phase excitation, the amount of change is 45 °. When the excitation mode is 2W1-2 phase excitation, the amount of change is 11.25 °. The excitation mode corresponding to the value of the mode signal MODE1 and the change amount corresponding to the excitation mode may be stored in the target position generation unit 113 or may be stored in the register 114.

  The register 114 stores data including various parameters used for vector control of the motor M. The external device can read data stored in the register 114 using serial communication. The external device can write data to the register 114 using serial communication.

  The vector control unit 115 generates a control signal for controlling the motor M based on the target position generated by the target position generation unit 113 and the parameters stored in the register 114. Specifically, the vector control unit 115 performs vector calculation based on the target position and parameters, calculates the q-axis component (torque component) and the d-axis component (magnetic flux component) of the current command value, and calculates the voltage command value A q-axis component and a d-axis component are calculated. Then, the vector control unit 115 converts the calculated voltage command value from the rotating coordinate system composed of the d-axis and the q-axis to a fixed coordinate system corresponding to the motor M, and generates a control signal (voltage command value). . In the example of FIG. 1, an A-axis voltage command value and a B-axis voltage command value are generated as control signals.

  In the example of FIG. 2, it is assumed that the motor control unit 11 performs open loop control of the motor M. However, by feeding back the measured value of the current flowing through the motor M to the vector control unit 115, the motor control unit 11 can also feedback control the motor M. Thereby, the motor M can be controlled with higher accuracy.

  The PWM signal generation unit 116 performs pulse width modulation on the control signal, and generates a PWM signal corresponding to the control signal. The PWM signal generated by the PWM signal generation unit 116 is output from the terminal Tout.

  Next, processing of the motor control device 1 will be described. FIG. 3 is a flowchart illustrating an example of processing performed by the mode signal generation unit 111 and the serial communication unit 112. In the following, it is assumed that signals are input from the terminals Ts and T1 to T3 at the start of processing.

  When signals are input from the terminals Ts and T1 to T3, the mode signal generation unit 111 and the serial communication unit 112 confirm the value of the selection signal SEL input from the terminal Ts (step S101).

  When the value of the selection signal SEL is 0 (YES in step S101), the mode signal generation unit 111 generates the mode signal MODE1 based on the mode signal mode1, the mode signal mode2, and the mode signal mode3 (step S102). The mode signal generation unit 111 inputs the generated mode signal MODE1 to the target position generation unit 113. At this time, the serial communication unit 112 does not perform processing.

  On the other hand, when the value of the selection signal SEL is 1 (NO in step S101), the mode signal generation unit 111 holds the mode signal MODE1 immediately before the value of the selection signal SEL changes to 1, and the target position generation unit 113. (Step S103).

  The serial communication unit 112 performs serial communication with an external device via the terminals T1 to T3 (step S104). That is, the serial communication unit 112 receives the serial reception data RXD from the terminal T1 and transmits the serial transmission data from the terminal T2 in accordance with the clock SCK input from the terminal T3.

  The motor control device 1 repeats the processes of steps S101 to S104. The motor control device 1 ends the above processing when the power is turned off or the end of processing is notified from an external device.

  FIG. 4 is a flowchart illustrating an example of processing performed by the target position generation unit 113, the vector control unit 115, and the PWM signal generation unit 116. In the following, it is assumed that the clock CLK, the direction signal DIR, and the mode signal MODE1 are input to the target position generation unit 113 at the start of processing. The value of the selection signal SEL may be 0 or 1. This is because, as described above, the mode signal MODE1 is input to the target position generation unit 113 regardless of the value of the selection signal SEL. Further, it is assumed that each value of the mode signal MODE1 is associated with an excitation mode and a standby state.

  When the mode signal MODE1 is input, the target position generation unit 113 checks the contents specified by the input mode signal MODE1 (step S201). When the mode signal MODE1 designates any excitation mode (YES in step S201), the target position generation unit 113 detects the edge of the clock CLK (step S202).

  When the target position generation unit 113 detects the edge, the target position generation unit 113 generates a target position of the motor M based on the mode signal MODE1 and the direction signal DIR (step S203). The method for generating the target position is as described above. The target position generation unit 113 inputs the generated target position to the vector control unit 115.

  When the target position is input, the vector control unit 115 generates a control signal using the parameter read from the register 114 (step S204). The method for generating the control signal is as described above. The vector control unit 115 inputs the generated control signal to the PWM signal generation unit 116.

  When the control signal is input, the PWM signal generation unit 116 generates a PWM signal based on the input control signal (step S205). The method for generating the PWM signal is as described above. The PWM signal generation unit 116 outputs the generated PWM signal from the terminal Tout. The PWM signal output from the terminal Tout is input to the driver unit 12. When the PWM signal is input, the driver unit 12 supplies power corresponding to the input PWM signal to the motor M (step S205). Thereby, the motor M is driven so that the position of the rotor becomes the target position.

  On the other hand, when the mode signal MODE1 designates the standby state (NO in step S201), the target position generator 113 determines that the time during which the mode signal MODE1 continuously designates the standby state is the first threshold time Tth1. Is determined (step S206). The target position generation unit 113 may determine whether the number of times that the mode signal MODE1 continuously designates the standby state exceeds a predetermined number. For example, setting 64 as the predetermined number of times corresponds to setting 1.28 us as the first threshold time Tth1 when the frequency of the clock CLK is 50 MHz.

  When the time during which the mode signal MODE1 continuously designates the standby state has not passed the first threshold time Tth1 (NO in step S206), the process proceeds to step S202. On the other hand, when the time during which the mode signal MODE1 continuously designates the standby state has exceeded the first threshold time Tth1 (YES in step S206), the target position generation unit 113 shifts to the standby state ( Step S207).

  In this way, by setting the insensitive time (first threshold time Tth1), the target position generation unit 113 shifts to the standby state when the mode signal MODE1 erroneously designates the standby state due to the influence of noise or the like. This can be suppressed.

  The target position generation unit 113 stops the target position generation processing (steps S202 to S205) in the standby state. In addition to the target position generation unit 113, the vector control unit 115, the PWM signal generation unit 116, and the driver unit 12 may shift to a standby state and stop operating.

  Thereafter, the target position generation unit 113 confirms the contents specified by the input mode signal MODE1 (step S208). When the mode signal MODE1 designates any excitation mode (YES in Step S208), the target position generation unit 113 determines that the time during which the mode signal MODE1 designates the excitation mode continuously is the second threshold time. It is determined whether Tth2 has elapsed (step S209). The target position generation unit 113 may determine whether the number of times that the mode signal MODE1 continuously designates the excitation mode exceeds a predetermined number. For example, setting 64 as the predetermined number of times is equivalent to setting 1.28 us as the second threshold time Tth2 when the frequency of the clock CLK is 50 MHz.

  If the time during which the mode signal MODE1 continuously designates the excitation mode has not passed the second threshold time Tth2 (NO in step S209), the process returns to step S208. On the other hand, when the time during which the mode signal MODE1 continuously designates the excitation mode has passed the second threshold time Tth2 (YES in step S209), the target position generator 113 returns from the standby state ( Step S210). Thereafter, the process proceeds to step S202.

  In this way, by setting the insensitive time (second threshold time Tth2), the target position generator 113 returns from the standby state when the mode signal MODE1 erroneously specifies the excitation mode due to the influence of noise or the like. This can be suppressed.

  The motor control device 1 repeats the processes of steps S201 to S210. The motor control device 1 ends the above processing when the power is turned off or the end of processing is notified from an external device.

  As described above, according to the present embodiment, since the terminals T1 to T3 can be shared as terminals for serial communication and generation of the mode signal MODE1, an increase in the number of terminals can be suppressed. Thereby, the area of the chip constituting the motor control device 1 can be reduced, and the manufacturing cost of the motor control device 1 can be reduced.

  Further, according to the present embodiment, the motor control device 1 can perform serial communication with an external device while driving the motor M. Therefore, the external device can update the vector control parameters while the motor control device 1 is driving the motor M. Further, the external device can acquire the internal state of the motor control device 1 driving the motor M in real time.

Second Embodiment
A motor drive system according to the second embodiment will be described with reference to FIG. In the present embodiment, a motor control drive system capable of changing the excitation mode of the motor M during execution of serial communication (while the value of the selection signal SEL is 1) will be described. Hereinafter, the difference from the first embodiment will be mainly described.

  FIG. 5 is a diagram illustrating an example of the configuration of the motor control unit 11 according to the present embodiment. The motor control unit 11 in FIG. 5 includes a selector 117. Other configurations are the same as those of the first embodiment.

  The selector 117 receives the mode signal MODE1 from the mode signal generator 111, and receives the mode signal MODE2 (second mode signal) and the selection signal sel from the register 114. The selector 117 inputs the mode signal MODE1 or the mode signal MODE2 to the target position generation unit 113 in accordance with the selection signal sel. The target position generation unit 113 generates a target position based on the input mode signal MODE1 or mode signal MODE2.

  In the present embodiment, the mode signal generation unit 111 inputs the generated mode signal MODE1 to the selector 117 instead of the target position generation unit 113. The register 114 stores in advance a mode signal MODE2 for designating the excitation mode of the motor M. The mode signal MODE2 can be changed from an external device by serial communication.

  The selection signal sel is a signal that specifies which of the mode signals MODE1 and MODE2 is input to the target position generation unit 113, and the two values correspond to the mode signals MODE1 and MODE2, respectively. Hereinafter, a value 0 of the selection signal sel indicates that the mode signal MODE1 is input, and a value 1 indicates that the mode signal MODE2 is input. The value of the selection signal sel is set to 0 by default and can be changed to 1 by serial communication.

  The operation of the motor control device 1 when the value of the selection signal sel is 0 is the same as in the first embodiment. That is, when the value of the selection signal SEL is 0, the mode signal MODE1 generated by the mode signal generation unit 111 is input to the target position generation unit 113. When the value of the selection signal SEL is 1, the mode signal MODE 1 held by the mode signal generation unit 111 is input to the target position generation unit 113.

  On the other hand, the operation of the motor control device 1 when the value of the selection signal sel is 1 is different from that of the first embodiment. That is, when the value of the selection signal sel is 1, the mode signal MODE2 stored in the register 114 is input to the target position generation unit 113 regardless of the value of the selection signal SEL. However, since the serial communication is not performed when the value of the selection signal SEL is 0, the value of the mode signal MODE2 is constant. On the other hand, when the value of the selection signal SEL is 1, the value of the mode signal MODE2 can be changed by serial communication.

  As described above, according to the present embodiment, the excitation mode of the motor M is changed by changing the value of the mode signal MODE2 by serial communication during execution of serial communication (while the value of the selection signal SEL is 1). Can be changed.

  It should be noted that the present invention is not limited to the configuration shown here, such as a combination with other elements in the configuration described in the above embodiment. These points can be changed without departing from the spirit of the present invention, and can be appropriately determined according to the application form.

1: Motor control device 11: Motor control unit 12: Driver unit 111: Mode signal generation unit 112: Serial communication unit 113: Target position generation unit 114: Register 115: Vector control unit 116: PWM signal generation unit 117: Selector M: motor

JP 2011-010388 A

Claims (12)

A first shared terminal;
A selection terminal to which a selection signal is input;
When the selection signal is a first value, a mode signal generation unit that generates a first mode signal that specifies an excitation mode of a motor based on an input signal from the first shared terminal;
When the selection signal is a second value, a serial communication unit that performs serial communication with an external device using an input signal from the first shared terminal;
A target position generator for generating a target position of the motor based on the first mode signal;
A vector control unit that generates a control signal for controlling the motor based on the target position;
A motor control device comprising: A second shared terminal;
The mode signal generation unit generates the first mode signal based on an input signal from the second shared terminal,
The motor control device according to claim 1, wherein the serial communication unit performs serial communication with the external device by using an output signal from the second shared terminal. A third shared terminal;
The mode signal generation unit generates the first mode signal based on an input signal from the third shared terminal,
The motor control device according to claim 1, wherein the serial communication unit performs serial communication with the external device using an output signal from the third shared terminal. 2. The motor control device according to claim 1, wherein the first shared terminal receives a first bit of the first mode signal or serial reception data. The motor control device according to claim 2, wherein the second shared terminal receives a second bit of the first mode signal and outputs serial transmission data. 4. The motor control device according to claim 3, wherein the third shared terminal receives a third bit or a clock of the first mode signal. The said mode signal generation part hold | maintains the said 1st mode signal immediately before changing, when the said selection signal changes from the said 1st value to the said 2nd value. The motor control apparatus described. The motor control device according to any one of claims 1 to 7, wherein the excitation mode includes at least one of one-phase excitation, two-phase excitation, 1-2 phase excitation, and a standby state. The motor control device according to claim 1, further comprising a PWM signal generation unit that generates a PWM (Pulse Width Modulation) signal according to the control signal. The motor control device according to claim 9, further comprising a driver unit that supplies electric power to the motor in accordance with the PWM signal. A register for storing a second mode signal designating the excitation mode of the motor;
A selector for inputting the first mode signal or the second mode signal to the target position generation unit;
The motor control device according to any one of claims 1 to 10, further comprising: The motor;
A motor control device according to any one of claims 1 to 11,
A motor drive system comprising:

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