Current Sensor Module (ACS712ELCTR-20A) เป็นโมดูลวัดกระแสขนาด 20 แอมป์ โดยอาศัยหลักการ ฮอลเอฟเฟค สามารถใช้ได้ทั้งไฟ AC และ DC

Sensing and controlling current flow is a fundamental requirement in a wide variety of applications including, over-current protection circuits, battery chargers, switching mode power supplies, digital watt meters, programmable current sources, etc. This ACS721 current module is based on ACS712 sensor, which can accurately detect AC or DC current. The maximum AC or DC that can be detected can reach 20A, and the present current signal can be read via analog I / O port of Arduino.

Features:

• AC/DC Current to Voltage Conversion
• Accuracte Sensing Range: -20A to +20A 
• Current to Voltage Ratio: 100mV/A
• Operating Voltage: 5V
• Total Output Error: ±1.5%
• On-board Power Indicator

Size: 

• 30.48 x 12.7mm

• เอกสารเพิ่มเติม (Datasheet)
• ตัวอย่างการใช้งาน 

โค้ดตัวอย่าง

วัดแอมป์ไฟกระแสตรง

void setup() {
 Serial.begin(9600);
} 

void loop() {

  float average = 0;

  for(int i = 0; i < 1000; i++) {

    average = average + (.0264 * analogRead(A0) -13.51) / 1000;

    //5A mode, if 20A or 30A mode, need to modify this formula to 

    //(.19 * analogRead(A0) -25) for 20A mode and 

    //(.044 * analogRead(A0) -3.78) for 30A mode

    delay(1);

  }

  Serial.println(average);  

}

วัดแอมป์ไฟกระแสสลับ

#define CURRENT_SENSOR A0  // Define Analog input pin that sensor is attached

float amplitude_current;      // Float amplitude current

float effective_value;       // Float 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 Arduino interface of the sensor is 5v

    amplitude_current=(float)(sensor_max-512)/1024*5/185*1000000; // for 5A mode,you need to modify this with 20 A and 30A mode;

    effective_value=amplitude_current/1.414;

    //for minimum current=1/1024*5/185*1000000/1.414=18.7(mA)

    //Only sinusoidal alternating current

    Serial.println("The amplitude of the current is(in mA)");

    Serial.println(amplitude_current,1);

    //Only one number after the decimal poin

    Serial.println("The effective value of the current is(in mA)");

    Serial.println(effective_value,1);

}

void pins_init()
{
  pinMode(CURRENT_SENSOR, INPUT);
}

/*Function: Sample for 1000ms and get the maximum value from the S 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(CURRENT_SENSOR);

        if (sensorValue > sensorMax)

        {

            /*record the maximum sensor value*/

           sensorMax = sensorValue;

        }

    }

    return sensorMax;

}

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