Arduino添加作業

Question

我使用Arduino進行了一些編程，但是我遇到了問題。在loop()函數中，我想爲每個執行loop()函數的變量添加值pwm。我從我寫的一些函數中獲得這個值，並用命令pwm += result將它添加到pwm，但它不起作用。如果我打印pwm，我總是得到零。即使打印result給了我一些非零值。整個代碼：

float pwm = 0; 
float result = 0; 

void loop(){ 

    .... 

    errV = w - cm; 
    errDtV = errOldV - errV; 

    result = flc->cog(errV, errDtV); 

    Serial.print("RESULT: "); 
    Serial.println(result); 

    pwm += result; 
    Serial.println(pwm); 
} 

和輸出是這樣的：

RESULT: 31.98 
0.00 

可能是什麼問題？

編輯：這裏是整個小品

#include "FSet.h" 
#include "FRule.h" 
#include "Flc.h" 
#include <NewPing.h> 
#include "MotorControl.h" 

MotorControl* m; 
Flc* flc; 
FRule* rule1,*rule2,*rule3,*rule4,*rule5,*rule6,*rule7,*rule8,*rule9; 

NewPing sonar1(32,33,200); 

static int dirA = 9; 
static int pwmA = 8; 

// Setup the FSets 
FSet errZ(0,5,0); 
FSet errMP(-15,15,0); 
FSet errLP(-30,15,-1); 

FSet errDtLN(-4,2,-1); 
FSet errDtMN(-2,2,0); 
FSet errDtZ(0,2,0); 
FSet errDtMP(2,2,0); 
FSet errDtLP(4,2,1); 

FSet cntLN(-40,20,0); 
FSet cntMN(-20,20,0); 
FSet cntZ(0,20,0); 
FSet cntMP(20,20,0); 
FSet cntLP(40,20,0); 

void setup(){ 
    Serial.begin(4800); 
    pinMode(dirA,INPUT); 

    //Creating FRules for test  
    rule1 = new FRule(&errZ,&errDtMP,&cntMN); 
    rule2 = new FRule(&errZ,&errDtZ,&cntZ); 
    rule3 = new FRule(&errZ,&errDtMN,&cntMP); 
    rule4 = new FRule(&errMP,&errDtLP,&cntMN); 
    rule5 = new FRule(&errMP,&errDtMN,&cntMP); 
    rule6 = new FRule(&errLP,&errDtMP,&cntMP); 
    rule7 = new FRule(&errLP,&errDtZ,&cntLP); 
    rule8 = new FRule(&errLP,&errDtMN,&cntLP); 
    rule9 = new FRule(&errLP,&errDtLN,&cntLP); 

    flc = new Flc(9); 
    flc->addRule(rule1); 
    flc->addRule(rule2); 
    flc->addRule(rule3); 
    flc->addRule(rule4); 
    flc->addRule(rule5); 
    flc->addRule(rule6); 
    flc->addRule(rule7); 
    flc->addRule(rule8); 
    flc->addRule(rule9); 

} 

int errV = 0; 
int errOldV = 0; 
int errDtV = 0; 
int w = 30; 
unsigned int uS; 
unsigned int cm; 

float pwm1 = 0; 
float result = 0; 

void loop(){ 
    uS = sonar1.ping(); 
    cm = (uS/US_ROUNDTRIP_CM); 

    errV = w - cm; 
    errDtV = errOldV - errV;  

    result = flc->cog(errV,errDtV); 

    Serial.print("RESULT: "); 
    Serial.println(result); 

    pwm1 = pwm1 + result; 

    Serial.println(pwm1); 
    analogWrite(pwmA,pwm1); 

    errOldV = errV; 

} 

FLC類的頭文件： 的#ifndef FLC_H 的#define FLC_H 的#include 「Arduino.h」 的#include 「FRule.h」

class Flc { 
    public: 
     Flc(int size); 
     ~Flc(); 
     int addRule(FRule* rule); 
     int mom(float x1,float x2); 
     float cog(float x1,float x2); 

     FRule** rules; 

    private: 
     int last; 
     int size; 
     float h; 
     float numerator = 0; 
     float denominator = 0; 
     float result = 0; 

}; 

#endif 

FLC類源： ＃包括 「Arduino.h」 的#include 「Flc.h」

Answer 1

你的函數cog（）中的某些東西正在跺腳變量pwm。一旦float變量損壞，Serial.print（）將只顯示零。下面的示例顯示浮點數設置爲0xffffff時，浮點數學庫將停止對該變量進行任何操作。

運行下面的示例程序，您將看到一次pwm正確打印。在第一次錯誤的通話之後，它會打印零。所佔用的內存也不再改變。

pwm=0.50 zpwm=0.50 
pwm=0.00 zpwm=3.95 result=3.45 
255-255-255-255 
pwm=0.00 zpwm=4.45 
pwm=0.00 zpwm=7.90 result=3.45 
255-255-255-255 

示例程序顯示寫入錯誤內存位置的函數。 查看鏈接器輸出的內存映射，變量按列出的順序放置在內存中。所以寫過var的結尾，會破壞pwm。

float zpwm = 0; 
byte var = 0; 
float pwm = 0; 
float result = 0; 


float badactor() { 
    *((long*)(&var+1)) = -1; 
    return 3.45; 
} 

void setup() { 
    Serial.begin(57600); 
} 

void loop() { 

    zpwm += 0.5; 
    pwm += 0.5; 

    Serial.print("pwm="); 
    Serial.print(pwm); 
    Serial.print(" zpwm="); 
    Serial.println(zpwm); 

    result = badactor(); 
    pwm += result; 
    zpwm += result; 

    Serial.print("pwm="); 
    Serial.print(pwm); 
    Serial.print(" zpwm="); 
    Serial.print(zpwm); 
    Serial.print(" result="); 
    Serial.println(result); 

    uint8_t* ptr; 
    ptr = (uint8_t*)&pwm; 
    Serial.print((int)*(ptr)); 
    Serial.print("-"); 
    Serial.print((int)*(ptr+1)); 
    Serial.print("-"); 
    Serial.print((int)*(ptr+2)); 
    Serial.print("-"); 
    Serial.println((int)*(ptr+3)); 

    delay(1000); 
}