Question

我正在为我的DHT传感器创建一个库。我有两个名称为AM_2301.cpp和AM_2301.h的文件：

AM_2301.h：

#ifndef AM2301_h
#define AM2301_h

#include "Arduino.h"

struct Two_float {
    float temp;
    float humidity;
};

extern int pinn;

class AM_2301
{
  public:
    AM_2301(int pin);
    void begin();
    struct Two_float read();
  private:
    int _pin;
};

#endif

AM_2301.cpp：

#include "Arduino.h"
#include "AM_2301.h"
#include "DHT.h"

//#define pinn 3
int pinn;
DHT dht(pinn, DHT21);

AM_2301::AM_2301(int pin)
{
    pinMode(pin, OUTPUT);
    Serial.print("pinn: ");
    Serial.println(pinn);
    _pin = pin;
    pinn = pin;
    //DHT dht(pinn, DHT21);
}


void AM_2301::begin(){
    dht.begin();
}

struct Two_float AM_2301::read()
{
    struct Two_float output;
    float h = dht.readHumidity();
    float t = dht.readTemperature();
    // check if returns are valid, if they are NaN (not a number) then something went wrong!
    if (isnan(t) || isnan(h))
    {
        Serial.println("Failed to read from DHT");
        t = 0;
        h = 0;
    }
    output = {t, h};
    return output;
}

和main.cpp：

#include "Arduino.h"
#include "AM_2301.h"

int pin =3 ;

AM_2301 AM(pin);

void setup() {
    // put your setup code here, to run once:
    Serial.begin(115200);
    AM.begin();
}

void loop() {

    struct Two_float val;
    val = AM.read();
    Serial.print("Temp: ");
    Serial.print(val.temp);
    Serial.print(" , ");
    Serial.print("Humidity: ");
    Serial.println(val.humidity);
    delay(2000);
    // put your main code here, to run repeatedly:
}

但问题是我想在构造函数中声明一个引脚号，并且该引脚转到AM_2301.cpp中的另一个构造函数但我不知道如何实现它。我想让dht对象成为我班级中所有其他函数的全局对象。

Answer 1

最后我根据paddy的answer找到了一个解决方案我必须使用来自我的静态实例的指针。以下是修改后的AM_2301.cpp：

#include "Arduino.h"
#include "AM_2301.h"
#include "DHT.h"

static DHT *dht = NULL;  //define the pointer


AM_2301::AM_2301(int pin)
{
    pinMode(pin, OUTPUT);
    Serial.print("_pin: ");
    Serial.println(_pin);
    _pin = pin;
    dht = new DHT(_pin, DHT21);  //pass the initialization
}


void AM_2301::begin(){
    dht->begin();
}

struct Two_float AM_2301::read()
{
    struct Two_float output;
    float h = dht->readHumidity();
    float t = dht->readTemperature();
    // check if returns are valid, if they are NaN (not a number) then something went wrong!
    if (isnan(t) || isnan(h))
    {
        Serial.println("Failed to read from DHT");
        t = 0;
        h = 0;
    }
    output = {t, h};
    return output;
}

Answer 2

您需要将<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:padding="10dp" android:layout_width="match_parent" android:layout_height="match_parent"> <ImageView android:id="@+id/movieImage" android:layout_width="match_parent" android:layout_height="70dp" android:layout_marginRight="5px" android:src="@drawable/fruits" /> <LinearLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_toEndOf="@id/movieImage" android:orientation="vertical"> //below text is to appear beneath the first image <TextView android:id="@+id/nameTxt" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginTop="5dp" android:text="Name" android:textSize="20sp" /> //below layout to appear beneath the above text <LinearLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="7dp" android:layout_marginTop="4dp" android:layout_toEndOf="@id/movieImage" android:orientation="horizontal"> <ImageView android:id="@+id/img1" android:layout_width="16dp" android:layout_height="16dp" android:layout_toEndOf="@id/movieImage" android:layout_marginRight="5px" android:src="@drawable/thumbsupr" /> <TextView android:id="@+id/exp1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="10" android:textSize="20sp" android:layout_toEndOf="@id/img1" /> <ImageView android:id="@+id/img2" android:layout_width="16dp" android:layout_height="16dp" android:layout_marginLeft="5dp" android:layout_toEndOf="@id/exp2" android:layout_marginRight="5px" android:src="@drawable/thumbsdownr" /> <TextView android:id="@+id/exp2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="5" android:textSize="20sp" android:layout_toEndOf="@id/img2" /> </LinearLayout> </LinearLayout> </RelativeLayout>对象作为DHT类的一部分，然后使用member initializer list对其进行初始化。

AM_2301.h

AM_2301

AM_2301.cpp

#ifndef AM2301_h
#define AM2301_h

#include "Arduino.h"

struct Two_float {
    float temp;
    float humidity;
};

class AM_2301
{
  public:
    AM_2301(int pin);
    void begin();
    struct Two_float read();
  private:
    DHT dht; // add a DHT object
};

#endif

在类中调用另一个构造函数作为全局

2 个答案: