c++ - Arduino:如果在构造函数中使用 this->object.attach(pin)，Servo 类会破坏伺服行为

Question

我对解决方案有疑问，但我不理解该解决方案。它可能类似于 Arduino: initialise custom object in constructor但我认为这不是同一个问题。

上下文如下。我正在用 Arduino 板控制一个小腿机器人。每条腿都是一个包含两个 Helm 机的对象“MChLeg”。使用库控制伺服系统。

问题如下:如果我在构造函数中分配 Helm 机，程序编译正常但 Helm 机行为异常(我想我破坏了 Helm 机调度)；如果我在构造函数之外分配 Helm 机，一切都很好。

下面我只列出了 C++ 类的一部分，它是唯一在工作版本和非工作版本之间发生变化的部分。

初始程序(在构造函数中分配伺服)，代码有问题:

#include <Arduino.h>
#include <Servo.h>

class MChLeg{
    int kneeIndex, hipIndex;
    int kneeAngle, hipAngle;
    Servo kneeServo; 
    Servo hipServo;
public:
    MChLeg(int, int); // (knee servo index, hip servo index); use 0 if no servo
    ~MChLeg();
    void setLeg(int, int); // (knee angle, hip angle); in degrees, 0-180, 90 is straight
    void rollLeg();
};

MChLeg::MChLeg(int x, int y){
    this->kneeIndex = x;
    this->hipIndex = y;
    if (this->kneeIndex != 0) {
        this->kneeServo.attach(this->kneeIndex);
        this->kneeServo.write(90);   // this line can be removed with no impact on issue
    }
    if (this->hipIndex != 0) {
        this->hipServo.attach(this->hipIndex);
        this->hipServo.write(90);    // this line can be removed with no impact on issue
    }
}

新代码(使用方法分配伺服)，代码运行良好:

#include <Arduino.h>
#include <Servo.h>

class MChLeg{
    int kneeIndex, hipIndex;
    int kneeAngle, hipAngle;
    Servo kneeServo; 
    Servo hipServo;
public:
    MChLeg();
    ~MChLeg();
    void assignLeg(int, int); // (knee servo index, hip servo index); use 0 if no servo
    void setLeg(int, int); // (knee angle, hip angle); in degrees, 0-180, 90 is straight
    void rollLeg();
};

MChLeg::MChLeg(){
    this->kneeIndex = 0;
    this->hipIndex = 0;
}

void MChLeg::assignLeg(int x, int y){
    if (this->kneeIndex != 0) {
        this->kneeServo.detach();
    }
    if (this->hipIndex != 0) {
        this->hipServo.detach();
    }
    this->kneeIndex = x;
    this->hipIndex = y;
    if (this->kneeIndex != 0) {
        this->kneeServo.attach(this->kneeIndex);
    }
    if (this->hipIndex != 0) {
        this->hipServo.attach(this->hipIndex);
    }
}

为什么第二个代码会比第一个更好？

调用代码:

// Include application, user and local libraries
#include <Servo.h>
#include "MChButton.h"
#include "MChLeg.h"


// pin connections
const int buttonIndex = 2; //pin for button
const int greenLed = 3;//pin for green Led
const int yellowLed = 4;//pin for yellow Led
const int redLed = 5;//pin for red Led
const int servoPin1 = 9;//pin for servo
const int servoPin2 = 10;//pin for servo
const int servoPin3 = 11;//pin for servo


//define persitent objects
MChButton theButton(buttonIndex); // declare the switch pin as an input
MChLeg rightLeg; // declare right leg - was 'MChLeg rightLeg(0, servoPin1);' in first version
MChLeg leftLeg;  // declare left leg - was 'MChLeg leftLeg(servoPin2, servoPin3);' in first version


// Setup phase
void setup(){

    // declare the LED pins as outputs
    pinMode(greenLed,OUTPUT);
    pinMode(yellowLed,OUTPUT);
    pinMode(redLed,OUTPUT);

    leftLeg.assignLeg(0, servoPin1); //right knee - hip - did not exist in first version
    rightLeg.assignLeg(servoPin2, servoPin3); //right knee - hip - did not exist in first version

}

// Loop phase
void loop(){

    //state machine counter (persistant)
    static int machinestate = 0;
    const int machinestateMax = 4; //max statemachine
    const int machinestateMax1 = machinestateMax+1; //max statemachine for modulo counting

    //check if there is an event, if there is one increment state machine counter and mark event done
    //statemachine counter is limited for machinestateMac (modulus)
    if (theButton.buttonEventGet()==true) {
        machinestate = ++machinestate % machinestateMax1;
    }

    // set LEDs and Legs according to state
    switch (machinestate) {
        case 0:{
            digitalWrite(greenLed, HIGH); // turn the green LED on pin 3 on
            digitalWrite(yellowLed, LOW);  // turn the red LED on pin 4 off
            digitalWrite(redLed, LOW);  // turn the red LED on pin 5 off
            leftLeg.setLeg(10, 10); // set leg to 0°
            rightLeg.setLeg(10, 10); //set leg to 0°
            break;
        }
        case 1:{
            digitalWrite(greenLed, HIGH);
            digitalWrite(yellowLed, HIGH);
            digitalWrite(redLed, LOW);
            leftLeg.setLeg(45, 45);
            rightLeg.setLeg(45, 45);
            break;
        }
        default:{ // detect if I did it wrong :-)
            digitalWrite(greenLed, HIGH); 
            digitalWrite(yellowLed, HIGH); 
            digitalWrite(redLed, HIGH);  
        }
    }
    delay(10);
}

感谢您的帮助。

Answer 1

我现在没有带 Arduino，但我记得遇到过同样的问题。

据我所知，我在我的构造函数中使用了一个 for 循环 来处理一个无效的数组。所以我最后只是一个一个地赋值。

如果使用 if 语句，我假设您遇到的问题。

今晚晚些时候回到家后，我会尝试不同的事情。

编辑 - 2015/01/08

我做了一些测试试图重现我所说的问题，但没有成功。我会保留我的答案作为解决方案可能。