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金属探测器？ 大家估计会喜欢吧？！

如下是电路图和源码，大家可以按此制作DIY

BOM清单：

R1= 330 Ω, resistor

R2= 1 KΩ, resistor

C1= 10nF, ceramic capacitor

D1= 1N4148, diode

BUZ1= Buzzer

LED1= 5mm any color LED

Arduino UNO Board or equivalent

成品图：

#define vinPin A5

#define buz 9

#define pulsePin A4

#define led 10

long sumExpect=0; //running sum of 64 sums

long ignor=0; //number of ignored sums

long diff=0; //difference between sum and avgsum

long pTime=0;

long buzPeriod=0;

void setup()

{

Serial.begin(9600);

pinMode(pulsePin, OUTPUT);

digitalWrite(pulsePin, LOW);

pinMode(vinPin, INPUT);

pinMode(buz, OUTPUT);

digitalWrite(buz, LOW);

pinMode(led, OUTPUT);

}

void loop()

{

int minval=1023;

int maxval=0;

long unsigned int sum=0;

for (int i=0; i<256; i++)

{

//reset the capacitor

pinMode(vinPin,OUTPUT);

digitalWrite(vinPin,LOW);

delayMicroseconds(20);

pinMode(vinPin,INPUT);

applyPulses();

//read the charge of capacitor

int val = analogRead(vinPin); //takes 13x8=104 microseconds

minval = min(val,minval);

maxval = max(val,maxval);

sum+=val;

long unsigned int cTime=millis();

char buzState=0;

if (cTime

{

if (diff>0)

buzState=1;

else if(diff<0)

buzState=2;

}

if (cTime>pTime+buzPeriod)

{

if (diff>0)

buzState=1;

else if (diff<0)

buzState=2;

pTime=cTime;

}

if (buzPeriod>300)

buzState=0;

if (buzState==0)

{

digitalWrite(led, LOW);

noTone(buz);

}

else if (buzState==1)

{

tone(buz,2000);

digitalWrite(led, HIGH);

}

else if (buzState==2)

{

tone(buz,500);

digitalWrite(led, HIGH);

}

}

//subtract minimum and maximum value to remove spikes

sum-=minval;

sum-=maxval;

if (sumExpect==0)

sumExpect=sum<<6; //set sumExpect to expected value

long int avgsum=(sumExpect+32)>>6;

diff=sum-avgsum;

if (abs(diff)>10)

{

sumExpect=sumExpect+sum-avgsum;

ignor=0;

}

else

ignor++;

if (ignor>64)

{

sumExpect=sum<<6;

ignor=0;

}

if (diff==0)

buzPeriod=1000000;

else

buzPeriod=avgsum/(2*abs(diff));

}

void applyPulses()

{

for (int i=0;i<3;i++)

{

digitalWrite(pulsePin,HIGH); //take 3.5 uS

delayMicroseconds(3);

digitalWrite(pulsePin,LOW); //take 3.5 uS

delayMicroseconds(3);

}

}