JP5988038B2 - Control circuit - Google Patents

Description

  The present invention relates to a control circuit, and more particularly to a control circuit that performs output control of a PWM (pulse width modulation) signal using a microcomputer.

  In LED lighting control, motor rotation control, and the like, there is a method of performing control using a pulse signal. This method generally uses a PWM output function of a microcomputer (hereinafter abbreviated as “microcomputer”).

  For example, a control circuit has been devised that performs complementary PWM output (outputs a pulse waveform with an opposite phase) with a duty ratio of 0% to 100% without burdening software (see Patent Document 1).

Japanese Patent No. 3687861

Renesas Microcomputer M16C Family / M16C / 50 Series User's Manual: Hardware

  When driving a plurality of loads using a plurality of PWM signal output functions, if the rising or falling timings of the plurality of pulse waveforms coincide with each other, a strong noise is generated, and a radio or smart keyless system (a user is connected to a wireless terminal). The ID verification by wireless communication is performed between the vehicle and the key only by approaching the vehicle with the key as follows: When the ID verification matches, the operation of the predetermined actuator is permitted and the user operates the key Without affecting the operation of other equipment, such as a door unlocking / locking or engine starting system).

  Since the configuration of Patent Document 1 relates to output control of a complementary PWM signal, the above-described noise generation is not taken into consideration. Further, in other prior arts, there is no disclosure or suggestion about countermeasures for noise generated by the coincidence of timings at a plurality of PWM signal outputs or the coincidence of the timings of PWM signal output and other signal outputs.

  Against the background of the above problems, an object of the present invention is to provide a control circuit capable of reducing noise generated by a pulse width modulation signal output and other signal outputs.

Means for Solving the Problems and Effects of the Invention

A control circuit for solving the above-described problems outputs a pulse width modulation signal based on a first setting unit that sets parameters including a period and a duty ratio of a pulse width modulation signal, and parameters set by the first setting unit An output timing adjustment parameter for adjusting the output timing of the pulse width modulation signal based on the output start timing of a pulse signal different from the pulse width modulation signal. After the first output unit starts outputting the pulse width modulation signal based on the parameter, the first setting unit sets a first parameter different from the output timing adjustment parameter, and the first output unit , when the first setting unit sets the first parameter based on the output timing adjusting parameters, leaving a pulse width modulated signal for at least one period After outputs a pulse width modulation signal based on the first parameter.

  With the above configuration, when outputting a PWM signal, it is possible to delay the output for a desired time, and it is possible to eliminate or reduce a phenomenon in which the rising or falling timing coincides with other signals. Therefore, generation of strong noise can be suppressed, and the influence on the operation of other devices such as a radio and a smart key can be prevented or reduced.

The figure which shows the structural example of the electronic control system to which the control circuit of this invention was applied. The figure which shows the structural example of a register group. The figure which shows the reference example of the structure for solving the problem which arises by a prior art. The flowchart explaining the PWM signal output control processing of this invention. The figure which shows the state of the PWM signal output in FIG.

  Hereinafter, the control circuit of the present invention will be described with reference to the drawings. FIG. 1 shows the overall configuration of an electronic control system 1 to which the control circuit of the present invention is applied. The electronic control system 1 includes, for example, an ECU 10 and a switch group 21, a sensor group 22, and an actuator group 31 that are mounted on the vehicle and connected to the ECU 10.

  The ECU 10 includes a microcomputer 11 (control circuit of the present invention) and a memory 12 (which may be built into the microcomputer 11) which is a nonvolatile storage medium such as a flash memory. The microcomputer 11 stores the control stored in the memory 12. Various functions of the ECU 10 are realized by executing the program.

  The microcomputer 11 includes a register group 110. By setting the register group, the function of the microcomputer 11 can be selected and executed / stopped. Note that the configuration of the microcomputer 11 (particularly related to the PWM function) is described in detail in, for example, Non-Patent Document 1, and therefore only an outline will be described in this embodiment. The microcomputer 11 and the register group 110 correspond to a first setting unit and a second setting unit of the present invention.

  In addition, the ECU 10 includes, for example, a signal for waveform shaping and A / D conversion of input signals from the switch group 21 on which the user performs operation input and the sensor group 22 including, for example, a rotation sensor, a pressure sensor, a temperature sensor, and the like. An input circuit 13 that performs processing, for example, a driver circuit 14 that drives and controls an actuator group 31 including a motor, a solenoid, and the like is included.

  With the above configuration, the ECU 10 calculates the operation control command value based on the data acquired from the switch group 21, the sensor group 22, or another ECU and the operation state of the actuator group 31, and performs drive control of the actuator group 31. .

  For the drive control of the actuator group 31, for example, a plurality of PWM signal output terminals of ch 1 (second output unit of the present invention) and ch 2 (first output unit of the present invention) of the microcomputer 11 are used. A PWM signal is output from the terminal to the driver circuit 14, and the driver circuit 14 generates a signal for driving the actuator group 31 and outputs the signal from the out1 terminal and the out2 terminal of the ECU 10, respectively.

FIG. 2 shows a configuration example of registers related to the PWM function in the register group 110.
PWM setting register: Sets whether to use the output terminal for PWM signal output (hereinafter referred to as “PWMn”).
Timer register: sets the period of the PWM signal (hereinafter referred to as “TMRn”).
Duty ratio setting register: Sets the duty ratio of each PWM signal (hereinafter referred to as “DUTYn”).
Count start flag: Start / stop of PWM signal output is controlled by starting / stopping the count (hereinafter referred to as “CNTn”).

  “N” is the channel number of the PWM signal output, n = 1 and 2, and corresponds to ch1 and ch2 in FIG. 1, respectively. In addition, for setting for each bit, bit 0 (b0) corresponds to ch1 and bit 1 (b1) corresponds to ch2.

  In the configuration of FIG. 2, first, 1 is set in each bit of the PWM setting register (PWMn), and the output terminal is set to be used for the output of the PWM signal. Next, the period of the PWM output signal is set by the timer register (TMRn), and the duty ratio is set by the duty ratio setting register (DUTYn). Then, 1 is set to each bit of the PWM output start flag (CNTn), and output of the PWM signal is started. The PWM signal is output while 1 is set in the PWM output start flag (CNTn).

  A reference example of a configuration for solving the problem caused by the conventional technique will be described with reference to FIG. In FIG. 3, the frequency of the two PWM signals (ch1 and ch2) is 2 kHz (period: 500 μsec), and the duty ratio (H-level time ratio) is 25%.

  As described above, first, interrupts by other functions of the microcomputer are prohibited. Next, when the output of the PWM signal of ch1 is started (time T1), the timer starts counting. This timer is for generating the start timing of the ch2 PWM signal output. When the timer reaches a predetermined value (time T2), the output of the ch1 PWM signal is started and interrupts are permitted. The interruption is performed to accurately adjust the output timing of the PWM signal of ch1 by the timer.

  In the configuration of FIG. 3, the output timing adjustment parameter includes a timer setting value for adjusting the output timing of the pulse width modulation signal. As a result, the rise and fall of the output waveforms of the ch1 and ch2 PWM signals do not overlap, and the problem as in the prior art does not occur. However, if the interrupt prohibition time (T2-T1: 250 μsec, for example) becomes longer, the possibility of affecting the operation of other functions increases. For example, in communication with a high baud rate such as CAN (Controller Area Network), there is a possibility that data cannot be received normally.

  FIG. 4 shows a flowchart of a PWM signal output control process for solving the problem occurring in FIG. This process is included in the control program described above, and is executed by the microcomputer 11 at a predetermined timing. The frequency of the two PWM signals (ch1 and ch2) is 2 kHz (cycle: 500 μsec) as in FIG. 3, and the duty ratio (H-level time ratio) is 25%.

  The configuration of the present invention is suitable when the frequencies of the two PWM signals are the same. It is also suitable when one of the frequencies of the two PWM signals is a multiple of the other. Even when the frequencies of the two PWM signals are other than the above, the rising or falling timings coincide with each other at the timing of the least common multiple of them, so that noise can be removed or suppressed at that time.

  First, the ch1 parameters (PWM1, TMR1, DUTY1, and the second parameter of the present invention) are set to have a frequency of 2 kHz and a duty ratio of 25% (S11). The duty ratio is a percentage obtained by dividing the Hi width in FIG. 4 by the sum (period) of the Hi width and the Low width.

In the above-described configuration, the second parameter includes a period and a duty ratio for making the pulse signal a pulse width modulation signal. With this configuration, even when the output from the second output unit is a pulse width modulation signal, the phenomenon that coincides with the rising or falling timing of the two signals can be eliminated or reduced.

  Next, each parameter of ch2 (PWM2, TMR2, DUTY2, output timing adjustment parameter of the present invention) is set to have a frequency of 4 kHz and a duty ratio of 0% (always outputs L level) (S12). It is desirable that the cycle be shorter than the cycle when performing drive control of the actuator group 31.

  In step S12 described above, the output timing adjustment parameter is such that the duty ratio is determined so that the output level of the pulse width modulation signal is constant within the output period, and the first parameter is the output target of the pulse width modulation signal. It is for performing operation control. With this configuration, for example, if the duty ratio is set to 0% (in the case of positive logic) or 100% (in the case of negative logic), the pulse width modulation signal is not affected without affecting the operation of the output target of the pulse width modulation signal. Output timing can be adjusted.

  In the configuration of step S12 described above, the period of the pulse width modulation signal in the output timing adjustment parameter is set shorter than the period of the pulse width modulation signal in the first parameter. With this configuration, an appropriate output timing can be set between the periods of the first parameter.

  Next, interrupts by other functions of the microcomputer are prohibited (S13). Then, output of the ch1 PWM signal is started (CNT1 set, S14). Subsequently, output of the PWM signal of ch2 is started (CNT2 set, S15), each parameter (TMR2, DUTY2, first parameter of the present invention) of ch2 is set to frequency 2 kHz, and the duty ratio is set to 25% (DUTY2, S16). ). Thereafter, the interruption is permitted (S17).

  The configuration of steps S13 and S17 described above prohibits interrupts by other functions of the control circuit before the first output unit or the second output unit starts outputting the pulse width modulation signal, respectively. Will allow interrupts after setting the first parameter. With this configuration, the output timing can be set more accurately.

  In the configuration of FIG. 4, when the frequency (TMRn) or the duty ratio (DUTYn) is rewritten while the PWM signal is being output, the microcomputer 11 maintains the state before being rewritten and the output for one cycle is completed. After that, output at a new frequency or duty ratio is started (so-called “double buffer”, see page 302 of Non-Patent Document 1).

  FIG. 5 shows the state of the output waveform of each channel in the configuration of FIG. ch1 always outputs a pulse signal having a frequency of 2 kHz and a duty ratio of 25% after the start of output. Ch2 outputs a signal (L level) having a frequency of 4 kHz and a duty ratio of 0% immediately after the start of output, and after one cycle (250 μsec) has elapsed, starts outputting a pulse signal at a frequency of 2 kHz and a duty ratio of 25%.

  The output state of the pulse waveform is the same as in FIG. 3, but the interrupt inhibition time (T11) is significantly shortened (˜several μsec). As a result, the possibility of affecting the operation of other functions due to the prohibition of interrupts is reduced.

In the above example, two PWM signals have been described as an example, but one (ch1) may be a pulse waveform output signal that does not use the PWM function. This configuration is, for outputting a pulse signal, comprising a second setting unit for setting a second parameter, and a second output section for outputting a pulse signal based on the second parameter, the first setting portion and the second The setting unit sets the output timing adjustment parameter and the second parameter, respectively. After the first output unit and the second output unit start outputting signals based on these parameters, the first setting unit Is set. With this configuration, even when the control circuit outputs another pulse signal that does not use PWM, a phenomenon that coincides with the rising or falling timing of the pulse signal can be eliminated or reduced.

  In addition to the continuous output of the pulse signal, the timing at which a pulse signal of an arbitrary width is generated only once (also called a one-shot pulse) at a predetermined timing coincides with the start timing of the ch2 PWM signal output. Also, the configuration of the present invention can be applied.

  Although the embodiments of the present invention have been described above, these are merely examples, and the present invention is not limited to these embodiments, and the knowledge of those skilled in the art can be used without departing from the spirit of the claims. Various modifications based on this are possible.

1 Electronic control system 11 Microcomputer (control circuit, first setting unit, second setting unit)
110 register group (first setting unit, second setting unit)
ch1 PWM signal output terminal (second output part)
ch2 PWM signal output terminal (first output part)

Claims (6)

A first setting unit for setting parameters including a period and a duty ratio of the pulse width modulation signal;
Based on the parameters set by the first setting unit, a first output unit that outputs the pulse width modulation signal;
With
The first setting unit sets an output timing adjustment parameter for adjusting an output timing of the pulse width modulation signal with reference to an output start timing of a pulse signal different from the pulse width modulation signal; After one output unit starts outputting a pulse width modulation signal based on the parameter,
The first setting unit sets a first parameter different from the output timing adjustment parameter,
When the first setting unit sets the first parameter, the first output unit outputs a pulse width modulation signal for at least one cycle based on the output timing adjustment parameter, and then sets the first parameter to the first parameter. A control circuit which outputs a pulse width modulation signal based thereon. The output timing adjustment parameter has a duty ratio determined so that the output level of the pulse width modulation signal is constant within the output period,
The control circuit according to claim 1, wherein the first parameter is for performing operation control of an output target of the pulse width modulation signal.   3. The control circuit according to claim 1, wherein a cycle of the pulse width modulation signal in the output timing adjustment parameter is set shorter than a cycle of the pulse width modulation signal in the first parameter. For outputting the pulse signal ;
A second setting unit for setting a second parameter;
A second output unit that outputs the pulse signal based on the second parameter;
With
The first setting unit and the second setting unit set the output timing adjustment parameter and the second parameter, respectively,
The first setting unit sets the first parameter after the first output unit and the second output unit start outputting signals based on these parameters. The control circuit according to item. The control circuit according to claim 4, wherein the second parameter includes a cycle and a duty ratio for making the pulse signal a pulse width modulation signal.   Before the first output unit or the second output unit starts outputting the pulse width modulation signal, interrupts by other functions of the control circuit are prohibited, and the first setting unit sets the first parameter. The control circuit according to claim 5, wherein the interrupt is permitted after the setting.

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