不能在库中使用 attachInterrupt [英] Can't use attachInterrupt in a library

问题描述

我正在为超声波距离传感器编写一个简单的库，并想尝试使用中断.

I'm writing a simple library for an ultrasonic distance sensor and thought i'd try using interrupts.

但是我无法在 attachCallback 方法中正确设置我的函数.

However i can't set my functions in the attachCallback method properly.

我希望 HCSR04Interrupt::echoHigh() 和 HCSR04Interrupt::echoLow() 在引脚分别变为高电平和低电平时调用.

I want HCSR04Interrupt::echoHigh() and HCSR04Interrupt::echoLow() called when the pin goes high and low respectively.

我已经用谷歌搜索了无济于事.Ardiuno IDE 说明如下:

I've Googled this to no avail. The Ardiuno IDE says the following:

./Arduino/libraries/HCSR04/HCSR04Interrupt.cpp: In member function 'void HCSR04Interrupt::getDistance()':
./Arduino/libraries/HCSR04/HCSR04Interrupt.cpp:31: error: argument of type 'void (HCSR04Interrupt::)()' does not match 'void (*)()'
./Arduino/libraries/HCSR04/HCSR04Interrupt.cpp: In member function 'void HCSR04Interrupt::echoHigh()':
./Arduino/libraries/HCSR04/HCSR04Interrupt.cpp:47: error: argument of type 'void (HCSR04Interrupt::)()' does not match 'void (*)()'

这是我的标题:

#ifndef _HCSR04Interrupt_
#define _HCSR04Interrupt_

#include "Arduino.h"

#define HCSR04_CM_FACTOR 58.0
#define HCSR04_IN_FACTOR 148.0
#define HCSR04_CM_MODE 0
#define HCSR04_IN_MODE 1

class HCSR04Interrupt {
  public:
    double distance;

    HCSR04Interrupt(int trigger_pin, int echo_pin, void (*callback)());

    void setUnits(int units);

    void getDistance();
  private:
    int _trigger_pin;
    int _echo_pin;
    int _units;
    unsigned long _micros_start;
    void (*_callback)();

    void initialize();
    void echoHigh();
    void echoLow();
};

#endif

还有我的实现(不完整，因为我无法通过 attachInterrupt 步骤):

And my implementation (not complete since i cant get past the attachInterrupt step):

#include "Arduino.h"
#include "HCSR04Interrupt.h"

HCSR04Interrupt::HCSR04Interrupt(int trigger_pin, int echo_pin, void (*callback)()) {
  _trigger_pin = trigger_pin;
  _echo_pin = echo_pin;
  _callback = callback;

  initialize();
}

void HCSR04Interrupt::setUnits(int units) {
  _units = units;
}

void HCSR04Interrupt::initialize() {
  pinMode(_trigger_pin, OUTPUT);
  pinMode(_echo_pin, INPUT);

  digitalWrite(_trigger_pin, LOW);
}

void HCSR04Interrupt::getDistance() {
  //Listen for the RISING interrupt
  attachInterrupt(_echo_pin - 2, echoHigh, RISING);

  //The trigger pin should be pulled high,
  digitalWrite(_trigger_pin, HIGH);

  //for 10 us.
  delayMicroseconds(20);

  //Then reset it.
  digitalWrite(_trigger_pin, LOW);
}

void HCSR04Interrupt::echoHigh() {
  _micros_start = micros();

  detachInterrupt(_echo_pin - 2);
  attachInterrupt(_echo_pin - 2, echoLow, FALLING);
}

void HCSR04Interrupt::echoLow() {
  detachInterrupt(_echo_pin - 2);

  unsigned long us = micros() - _micros_start;

  distance = us;

  (*_callback)();
}

推荐答案

所以 编译器(不是 IDE)会准确地告诉您问题所在:

So the compiler (not the IDE) tells you exactly what's wrong:

argument of type 'void (HCSR04Interrupt::)()' does not match 'void (*)()

因此，虽然 attachInterrupt() 使用 void (*)() 类型的函数指针，但您试图将它传递给 非静态成员函数， 你不能.您可以尝试使成员函数 static 和强制转换:

So, while attachInterrupt() takes a function pointer of type void (*)(), you're trying to pass it a non-static member function, which you can't. You can try making the member function static and casting:

static void echoHigh();

// ...

attachInterrupt(_echo_pin - 2, reinterpret_cast<void (*)()>(&echoHigh), RISING);

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