Energy Monitoring using Pachube, Arduino 1.0 and SCT-013-030

Energy monitoring using Arduino through it’s serial monitor completely well explained by openenergymonitor.org. We need some modifications on it to increase the monitoring capability with real time and historical graphical interface like pachube.

There are stuffs we’re gonna use in this project:

Microcontroller:

1x Arduino + EthernetShield. (i used Uno + Wiznet EtherShield)

Voltage sensing electronics:

1x 230V/9V AC-AC Power Adapter

1x 100kOhm resistor for step down voltage divider.

1x 10kOhm resistor for step down voltage divider.

2x 10kOhm resistors for biasing voltage divider

1x 10uF capacitor (for noise filtering purpose)

Current sensing electronics

1x CT sensor SCT-013-030 (Max 30A)

2x 10kOhm resistors

1x 10uF capacitor

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Since we use SCT-013-030 for the CT sensor, we don’t need to use burden resistor because it’s include on the device with 62  Ohms resistance and 1800 turn ratio.

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In this project, we want to display Irms and Vrms pachube style graphical. Therefore, we need to get Irms and Vrms from arduino calculation with data source coming  from  Analog ports where sensors connected.

We modify the EmonLib at EmonLib.cpp by adding :

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double EnergyMonitor::calcVrms(int NUMBER_OF_SAMPLES)
{
  int SUPPLYVOLTAGE = readVcc();
    for (int n = 0; n < NUMBER_OF_SAMPLES; n++)
  {
    lastSampleV = sampleV;
    sampleV = analogRead(inPinV);
    lastFilteredV = filteredV;
    filteredV = 0.996*(lastFilteredV+sampleV-lastSampleV);      // Root-mean-square method current
    // 1) square voltage values
    sqV = filteredV * filteredV;
    // 2) sum
    sumV += sqV;
  }
  double V_RATIO = VCAL *((SUPPLYVOLTAGE/1000.0) / 1023.0);
  Vrms = V_RATIO * sqrt(sumV / NUMBER_OF_SAMPLES);
  //Reset accumulators
  sumV = 0;
//--
   return Vrms;
}

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On the EmonLib.h by adding :

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double calcVrms(int NUMBER_OF_SAMPLES);

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And the sketch gonna be :

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#include "EmonLib.h" // 
Include Emon Library EnergyMonitor emon1;             // Create an instance 
void setup() 
 {
 Serial.begin(9600);   
 emon1.voltage(2, 234.26, 1.7);  // Voltage: input pin, calibration, phase_shift   
 emon1.current(1, 29); // Current: input pin, calibration. Cur Const= Ratio/BurdenR. 1800/62 = 29. 
 } 
void loop() {   
double Irms = emon1.calcIrms(1480); // Calculate Irms only   
double Vrms = emon1.calcVrms(1480); // Calculate Vrms only   
Serial.print(Irms); // Irms   
Serial.print(","); //   
Serial.println(Vrms); // Vrms 
}

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with sketch shown  above, we can get Irms, Vrms from serial monitor Arduino.

In order to posting it to pachube to get historical and realtime graphics, use this sketch and modify it to suit your API_KEY on pachube.

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With a jQuery touch  plus a lil bit php coding, we can get the interface we want to show; the current status, Irms and Vrms detail  graph powered by pachube.

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Pachube and Arduino IDE 1.0

 

Doing some HTTP PUT and GET to pachube.com using embedded system like Arduino is really nice. Latest software version  when i post this is arduino IDE 1.0. There are additions to this IDE like DHCP, DNS, and another interesting features. For people who usually use previous version of arduino IDE, there are things you need know before use this IDE 1.0.

In order to use arduino work together with pachube, this complete tutorial is sufficient. I made some modifications on the sketches so it’s suitable for IDE 1.0. Just put the extract files to your sketch directory to make it installed.

Before you apply the arduino to work together with pachube, you need to create account, api_key with full access (read-write), feed and datastreams. This documentation will lead you to catch there.

mqtt, mosquitto, arduino 1.0, pubsubclient !

1. install mosquitto on linux (mine, lenny) :

– download from mosquitto. i choose tarball for my lenny.

– tar zxvf mosquitto-0.15.tar.gz ; make ; make install

– executed :

lenny:~# mosquitto
1333960851: Warning: Mosquitto should not be run as root/administrator.
1333960851: mosquitto version 0.15 (build date 2012-04-07 16:53:42+0700) starting
1333960851: Opening ipv6 listen socket on port 1883.
1333960851: Opening ipv4 listen socket on port 1883.

2. download mosquitto for windows, for testing mosquitto_pub purposes.

– install it

– try publish topic :

C:\Program Files\mosquitto>mosquitto_pub -h YOUR_MOSQUITTO_IP_ADDRESS -t bar -m 123

3. Arduino 1.0 IDE for this sketch :

#include <SPI.h>
 #include <Ethernet.h>
 #include <PubSubClient.h>
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
 byte server[] = { 202, 51, xxx, xx }; // IP server mosquitto
void callback(char* topic, byte* payload, unsigned int length) {
 // handle message arrived
 Serial.println("Callback");
 Serial.print("Topic:");
 Serial.println(topic);
 Serial.print("Length:");
 Serial.println(length);
 Serial.print("Payload:");
 Serial.write(payload,length);
 Serial.println();
 }
PubSubClient client(server, 1883, callback);
void setup()
 {
 Serial.begin(9600);
 Ethernet.begin(mac);
 if (client.connect("arduino")) {
 client.publish("foo","hello world");
 client.subscribe("bar");// subscribe di topic "bar"
 }
 }
void loop()
 {
 client.loop();
 }

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– upload it, check your serial monitor.