พอดีผมจะเขียนโค๊ดคู่กับ sensor วัดกระแส ac โดยเมื่อมีการใช้ไฟ เกิน 30 mA relayก็จะทำงาน มากว่า 700mA ก็จะตัดrelay
และเมื่อมีการเสียบปลั๊กเข้า แล้วชักออก 1 ครั้ง จะได้ 0 mA ผมจะเอาค่ามันมาใช้เมื่อมีการชักปลั๊ก 10 ครั้งให้มัน relay ไป10 ซม
ผมเขียนโค๊ดแบบนี้อะคับ


int sensorTA12 = A0; // Analog input pin that sensor is attached to
int relay1 = A2;
int buttonState = 0;
int lastButtonState = 0;
const int sensorMin = 0;      
const int sensorMax = 1000;
const int R70 =  70;
const int R0 =  0;
float count = 0;
int i = 1;
float nVPP;   // Voltage measured across resistor
float nCurrThruResistorPP; // Peak Current Measured Through Resistor
float nCurrThruResistorRMS; // RMS current through Resistor
float nCurrentThruWire;     // Actual RMS current in Wire

#include <Wire.h>
#include <SPI.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);
void setup()
{
  pinMode (relay1, HIGH);
   Serial.begin(9600);
   pinMode(sensorTA12, INPUT);
   analogReference(DEFAULT);
   display.begin(SSD1306_SWITCHCAPVCC, 0x3C); // adres I2C mojego wyświetlacza
   display.clearDisplay();
}


void loop()
{
  
  
   nVPP = getVPP();
  
   /*
   Use Ohms law to calculate current across resistor
   and express in mA
   */
  
   nCurrThruResistorPP = (nVPP/200.0) * 1000.0;
  
  
  
   nCurrThruResistorRMS = nCurrThruResistorPP * 0.707;
  
  
   nCurrentThruWire = nCurrThruResistorRMS * 1000 ;

  
   Serial.print("Volts Peak : ");
   Serial.println(nVPP,3);

  
   Serial.print("Peak) : ");
   Serial.print(nCurrThruResistorPP,3);
   Serial.println(" mA Peak to Peak");
  
   Serial.print("RMS) : ");
   Serial.print(nCurrThruResistorRMS,3);
   Serial.println(" mA RMS");
  
   Serial.print("Wire : ");
   Serial.print(nCurrentThruWire ,3);
   Serial.println(" mA RMS");
  
   Serial.println();
    
       display.clearDisplay();// usatwienia lcd
       display.setTextSize(2);
       display.setTextColor(WHITE);
       display.setCursor(25,0);
       display.println("Current");
       display.setTextSize(1);
       display.setTextColor(WHITE);
       display.setCursor(28,17);
       display.println(nCurrentThruWire ,3);
       display.setTextColor(WHITE);
       display.setCursor(80,17);
       display.println("mA");
       display.display();
////////////////////////////////////////////////
int analogValue = analogRead(nCurrentThruWire);{
  if (analogValue > 30){
    digitalWrite(relay1,LOW);
    Serial.println("50");
    delay(10000);
    return;
  }
  else {                ///////////////// โค๊ดส่วนนี้อะคับที่ รับค่า 0
      buttonState = digitalRead(nCurrentThruWire);  
        if (buttonState == HIGH) {
    i = i +1;
    if (i > 10) {
      i = 1;
      
    }
  }

  switch (i) {
    case 1:
      digitalWrite(relay1,HIGH);
      Serial.println("001");
      delay(5000);
      return;
    case 2:
      digitalWrite(relay1,HIGH);
      Serial.println("002");
       delay(5000);
     break;
  
    case 3:
      digitalWrite(relay1,HIGH);
      Serial.println("003");
      delay(5000);
      break;
     case 4:
      digitalWrite(relay1,HIGH);
      Serial.println("004");
       delay(5000);
      break;
    case 5:
      digitalWrite(relay1,HIGH);
      Serial.println("005");
       delay(5000);
      return;
  
    case 6:
      digitalWrite(relay1,HIGH);
      Serial.println("006");
      delay(5000);
     break;
       case 7:
      digitalWrite(relay1,HIGH);
      Serial.println("007");
      delay(5000);
      break;
    case 8:
      digitalWrite(relay1,HIGH);
      Serial.println("008");
      delay(5000);
      break;
  
    case 9:
      digitalWrite(relay1,HIGH);
      Serial.println("009");
      delay(5000);
      break;
          case 10:
      digitalWrite(relay1,HIGH);
      Serial.println("0010");
      delay(5000);
      return;
  }
      
}
if (analogValue > 700){
    digitalWrite(relay1,HIGH);
    Serial.println("700");
  
  }
} // Analog
/////////////////////////////////////////////////

}// loop





float getVPP()
{
  float result;
  int readValue;             //value read from the sensor
  int maxValue = 0;          // store max valu
   uint32_t start_time = millis();
   while((millis()-start_time) < 1000) //sample for 1 Sec
   {
       readValue = analogRead(sensorTA12);
      
       if (readValue > maxValue)
       {
          
           maxValue = readValue;
       }
   }
  
  
   result = (maxValue * 5.0)/1024.0;
  
   return result;
}