FablabSU

Ceci est une ancienne révision du document !

---

//

  //  Function: Measure the amplitude current of the alternating current and 
  //            the effective current of the sinusoidal alternating current.
  //  Hardware: Grove - Electricity Sensor        
  //  Date:    Jan 19,2013
  //  by www.seeedstudio.com
  #define ELECTRICITY_SENSOR A0 // Analog input pin that sensor is attached to

  float amplitude_current;               //amplitude current
  float effective_value;       //effective current 

  void setup() 
  {
      Serial.begin(9600); 
      pins_init();
  }
  void loop() 
  {
      int sensor_max;
      sensor_max = getMaxValue();
      Serial.print("sensor_max = ");
      Serial.println(sensor_max);
      //the VCC on the Grove interface of the sensor is 5v
      amplitude_current=(float)sensor_max/1024*5/800*2000000;
      effective_value=amplitude_current/1.414;//minimum_current=1/1024*5/800*2000000/1.414=8.6(mA) 
                          //Only for sinusoidal alternating current
      Serial.println("The amplitude of the current is(in mA)");
      Serial.println(amplitude_current,1);//Only one number after the decimal point
      Serial.println("The effective value of the current is(in mA)");
      Serial.println(effective_value,1);
  }
  void pins_init()
  {
      pinMode(ELECTRICITY_SENSOR, INPUT);
  }
  /*Function: Sample for 1000ms and get the maximum value from the SIG pin*/
  int getMaxValue()
  {
      int sensorValue;             //value read from the sensor
      int sensorMax = 0;
      uint32_t start_time = millis();
      while((millis()-start_time) < 1000)//sample for 1000ms
      {
          sensorValue = analogRead(ELECTRICITY_SENSOR);
          if (sensorValue > sensorMax) 
          {
              /*record the maximum sensor value*/
              sensorMax = sensorValue;
          }
      }
      return sensorMax;
  }