The Electricity sensor module is a member of Grove. It is based on the TA12-200 current transformer which can transform the large AC into small amplitude. You can use it to test large alternating current up to 5A.
Features
Grove compatible interface
Maximum 5A input
High accuracy
Small size
!!!Tip More details about Grove modules please refer to Grove System
The following sketch demonstrates a simple application of measuring the amplitude of the alternating voltage. The SIG pin will output a alternating voltage based on the alternating current being measured. You can measure the value using ADC.
Put the alternating current wire through the hole of the current transformer.
Copy and paste code below to a new Arduino sketch.
/****************************************************************************/
// 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;
}
Upload the code.
Note The minimum effective current that can be sensed by the code can be calculated using the equation below. minimum_current=1/1024*5/800*2000000/1.414=8.6(mA).
Open the serial monitor, The results is as follows：
With Raspberry Pi
1.You should have got a raspberry pi and a grovepi or grovepi+.
2.You should have completed configuring the development enviroment, otherwise follow here.
3.Connection
Plug the sensor to grovepi socket A0 by using a grove cable.
4.Navigate to the demos' directory:
cd yourpath/GrovePi/Software/Python/
To see the code
nano grove_electricity_sensor.py # "Ctrl+x" to exit #
import time
import grovepi
# Connect the Grove Electricity Sensor to analog port A0
# SIG,NC,NC,GND
sensor = 0
grovepi.pinMode(sensor,"INPUT")
# Vcc of the grove interface is normally 5v
grove_vcc = 5
while True:
try:
# Get sensor value
sensor_value = grovepi.analogRead(sensor)
# Calculate amplitude current (mA)
amplitude_current = (float)(sensor_value / 1024 * grove_vcc / 800 * 2000000)
# Calculate effective value (mA)
effective_value = amplitude_current / 1.414
# minimum_current = 1 / 1024 * grove_vcc / 800 * 2000000 / 1.414 = 8.6(mA)
# Only for sinusoidal alternating current
print "sensor_value", sensor_value
print "The amplitude of the current is", amplitude_current, "mA"
print "The effective value of the current is", effective_value, "mA"
time.sleep(1)
except IOError:
print "Error"
