Published March 27, 2019

Home Power Monitor

This device monitors the total current coming into your home and performs and FFT on it to determine what appliances are running.

IntermediateFull instructions provided4 hours8,913

Things used in this project

Hardware components

Particle Photon

Current Transformer

Resistor 15 Ohm

Resistor 470 Ohm

Breadboard (generic)

Capacitor 10 µF

Software apps and online services

Particle Build Web IDE

Google Sheets

Story

Graph made in Google Sheets

Overview

This document will describe building a Google Sheet which receives household current data from a Particle Photon. At the end of each 24 hour period, the data will be copied over to a new sheet, which will be analyzed by a script which compares current magnitude changes between samples against known appliance signatures to determine how much power was consumed by a given appliance. The total power usage for the day, as well as the power consumed by each appliance, is then copied over to a “DailyLog” sheet which tracks each day’s totals. This guide assumes you are using a Particle Photon (https://www.particle.io/) and have followed their instructions on initial setup, etc. You will also need access to a Google Drive and have some basic familiarity with spreadsheets.

Showing Amplitude of different frequencies

Chart showing when different devices are on

Google SpreadSheet Setup

Begin by going to your Drive and creating a new Google Sheet that will collect the data from your Particle Photon. Give your spreadsheet a name, anything you like. The first column header must be called “Timestamp” (case sensitive). Subsequent columns can be given any name, but for the purpose of this project we will fill them out as:

Row 1 must match the JSON keys described later on in this document exactly. Row 2 is informational so the user can see which frequencies are represented in each column. This is configurable by the user and will be described in the Photon code portion of this document.

Row 3 will contain some formulas which help track total power consumption. Cell A3 should contain the formula:

=sum(-1*A4,INDEX(A4:A, COUNT(A4:A)))*24

This formula subtracts the first timestamp from the last timestamp and multiplies by 24 to give the total amount of time in hours from the first sample to the last. Cells B3 and M3 should respectively contain the formulas:

=average(B4:B)*A3*120/1000
=average(M4:M)*A3*120/1000

These formulas find the average current, multiply by the number of hours (A3), multiply by 120V and then divide by 1000 to get the total number of kilowatt-hours consumed on each phase for the day.

Highlight column A and click Format>Number>Date time in order to show the date and the time on the timestamp. Then, highlight cell A3 and change its format to Number>Number, since it is a number of hours rather than a timestamp.

You should end up with something like this:

Make a note of the name of the particular sheet within the document (“Sheet1” by default), as you will need it for the script later on. The Photon will be sending data to this spreadsheet, adding a new row each time. Add an additional sheet within this spreadsheet and insert this function in the first cell(A1):

=SORT(QUERY(Sheet1!A:Z,"order by A desc limit 90"),1,1)

This will copy the last 90 entries from Sheet1 and continuously update them, which will allow us to create dynamically updating charts. You can create additional sheets changing 90 to whatever value you want, allowing you to create charts of different time periods.

Like this:

Sort Function

Query Function

Google Sheets NOTE: sometimes, when you change a cell in Sheets, it doesn’t appear to take effect until you do something in another cell. If nothing happens when you add this “sort” function, type a random character into a random cell and hit enter. (Don’t forget to delete it later.) Or, just continue with this how-to and trust that it’s about to pop in there.

The Google Sheets Script

In order to set the spreadsheet up to receive data from the Photon, we’re going to create the script described here. From Google Sheets click Tools>Script Editor. This will open the script editor in a new tab. Give your project any name you like. Then replace the default text inside the Code.gs with the Google Sheets JavaScript(attached below).

You should have ended up with something like this:

Note that in line two, the variable SHEET_NAME must coincide with the name of the particular sheet within your spreadsheet that is receiving the data. So if you change it from the default of “Sheet1”, be sure to change it here as well.

Click the save icon, then run the setup function by clicking Run>Run function>setup. You will get a popup window to review permissions. Click “Review Permissions”, then in the next window click on your Google account. After that, you may receive a prompt that says “This app isn’t verified, ''if so, click “Advanced”, and then “Go to GenericScriptName(unsafe).” Then you can click “Allow” to give the script permission to edit your spreadsheet.

While still in the script editor, click File>Manage versions to create an initial version of the script. Give it a description, such as “InitialVersion” and click “save new version” and then “ok”.

Next we need to set up triggers for these scripts. To do this, click Edit>Current project’s triggers, which will open the G Suite Developer Hub in a new tab. Click the “+ Add Trigger” button in the bottom right corner” and in the popup window, from the dropdowns select ''doPost”, “Head”, ''From Spreadsheet”, and “On form submit”, and then click save. The failure notification settings can be set according to your preference of how often you want to be notified when the script fails. There will probably be another popup window for you to select your Google account again, then ask permissions to allow the script to edit the sheet, click “Allow”.

You will also need to create a trigger to run the copy_delete function daily, which duplicates Sheet1, renames the duplicated sheet with the day’s date, and then deletes all of the rows on Sheet1 to start a new day’s data. Click “+ Add Trigger” once again and select “Copy_delete”, “Head”, “Time-driven”, “day timer”, and “10pm to 11pm” (or whatever your preference for time) from the dropdown options. Note that the script will rename sheet with the day’s date, so you’ll want the time to be before midnight. Once again, the failure notifications can be set to your preference.

Likewise, add triggers for the appliance_id and getDailyTotal functions. These scripts should run AFTER the copy_delete function has run, so if you selected “10pm to 11pm” you could select “midnight to 1am” for appliance_id and “1am to 2am” for getDailyTotal, which must be run last.

You should end up with something like this:

Return to your script (the script editor tab) and click Publish>Deploy as web app. From the dropdowns select the relevant project version (probably 1), execute app as “Me”, and who has access “Anyone, even anonymous.” Click “deploy” and you will be given a url, which you will need for your webhook. Copy it and click “ok.” (You can save the link in notepad or something similar.)

The Webhook

For the webhook, we’re going to be elaborating on the method described in this tutorial. From the Particle Console, go to the Integrations page, and click on the “+ NEW INTEGRATION” box, then click “Webhook.” Give the webhook an Event Name, which will be the Particle.publishevent that initiates the webhook. For our purposes, it will be called “GenericWebhookName” (case sensitive). For url, paste the address that you were given when you published your script as a web app. Request Type is “POST”, Request Format is “Web Form”, and Device can be left as “Any.” The small dropdown at the bottom is “Advanced Settings” -

Click the “Advanced Settings” menu at the bottom and toggle the “Custom” radio button. Begin filling out the form fields.The order of the rows isn’t particularly important here. What’s worth noting is that the left column correlates with the column headers on your spreadsheet, and the right column is the key from the JSON key/value pairs you’re going to be sending. I’ve given them the same names for simplicity. All the rows are not shown in the pic below, but continue filling it out until you have a row for every column in your spreadsheet except the “Timestamp.”

Everything else can be left at it’s default setting. Click “Create Webhook.” The complete webhook should look like this:

The Firmware

Start off by updating your photon to the latest version of firmware. Click on the crosshairs(devices) on the bottom left of the build.particle.iowebpage for your devices. Click the drop down for the device you want to use and select the most recent system firmware. 0.8.0-rc.14 or newer is recommended, although older rc’s may work. The selected firmware target will be downloaded to your device the next time it is flashed.

For our project, you can use this code to upload to your Photon. For the general case, however, the format of publishing data to a spreadsheet using this webhook will look something like this:

Particle.publish("GenericWebhookName","{\"IrmsA\":\"" + tIrmsA + "\",\"A1\":\"" + A_1 + "\",\"A2\":\"" + A_2 + "\",\"A3\":\"" + A_3 + "\",\"A4\":\"" + A_4 + "\",\"A5\":\"" + A_5 + "\",\"A6\":\"" + A_6 + "\",\"A7\":\"" + A_7 + "\",\"A8\":\"" + A_8 + "\",\"A9\":\"" + A_9 + "\",\"A10\":\"" + A_10 + "\",\"IrmsB\":\"" + tIrmsB + "\",\"B1\":\"" + B_1 + "\",\"B2\":\"" + B_2 + "\",\"B3\":\"" + B_3 + "\",\"B4\":\"" + B_4 + "\",\"B5\":\"" + B_5 + "\",\"B6\":\"" + B_6 + "\",\"B7\":\"" + B_7 + "\",\"B8\":\"" + B_8 + "\",\"B9\":\"" + B_9 + "\",\"B10\":\"" + B_10 + "\"}",5,PRIVATE);

There are a few things to keep in mind with regard to the constants defined in the Photon firmware below. The number of samples must be a power of 2, and the sampling frequency must be an integer multiple of the number of samples. We’ve found that 4096 seems to be about the max sample rate that the Photon can reliably achieve. The constant “harm” is the number of harmonics to be captured on each phase, and “base_harm” is the lowest one. For example, we’ve defined “base_harm” as 20 and there are 10 harmonics per phase (20-200 in multiples of 20). Our testing has shown this to be roughly the range of useful information for our project.

Verify and flash your firmware (download the code to your device). This command is publishing an event called “GenericWebhookName” and generating a string of JSON formatted text that is sent to our script we created earlier. The variables being appended to the string above are string type. If all goes well, in your Particle console, you should see something like this:

Go back to you spreadsheet now and you should start seeing rows being added with your data. On Sheet2, which you set up to show the last X entries from Sheet1, you can create charts by selecting columns, and the charts will continuously update with your data.

Additional Sheet Setup

Now that your sheet is receiving data, you’ll need to set up a sheet which holds the individual appliance signatures that you will be testing against. Create a new sheet and give it the name “Appliances” (needs this exact name for the appliance_id script to work). Row 1 should be headers used to identify the columns.

To obtain the appliance signature, turn the appliance on and note on Sheet1 where the current changes. You may need to turn the same appliance on and off several times, noting the time, so you can find it’s signature. Single phase appliances (like your microwave) will only show up under the “A” phase or the “B” phase. Appliances like your air conditioner will change across the whole row. Once you “see” your appliance turn on as you’re watching Sheet1:

Highlight and copy the row immediately before and after the change you noticed:

Next, return to the Appliances sheet and paste the data into some blank cells:

Insert a function below this data that calculates the difference:

And copy that formula under each column. Once you have the entire row finished highlight and paste it into the next empty row in the list. Paste using “Ctrl+shift+V” in order to paste the values only and not the formula. This difference is your appliance’s signature.

Once you’ve copied the signature data into the appropriate row, you can delete the extra data and fill in the appliance name. You can also place 0’s in each column that is blank. The appliance_id script ignores frequencies where the magnitude change is less than 1 anyway (because the signal is drowned out by the noise), so you can replace any numbers less than 1 with 0’s for the sake of neatness. When you’re finished, it should look something like this:

Next, you’ll need a sheet to log the daily power usage. Create a new sheet titled “DailyLog”. For row 1, columns A-E should be labeled “Date”, “Phase A”, “Phase B”, “Total Power”, and “Total Cost”, with the subsequent columns matching your individual appliance names in the same order they are listed on your Appliances sheet. It will look something like this:

Concluding Remarks

You should now have a Google Sheet document which is receiving real time data from your Particle Photon into Sheet1. Once per day at the times you’ve designated, the copy_delete script should run first, then the appliance_id script, and finally the getDailyTotal script. To start the project, because we are keeping seven days of data (if you followed this tutorial exactly), the getDailyTotal script is going to delete the seventh sheet (or tab) from the left. Because you don’t want the script to accidentally delete your “DailyLog” or “Appliances” sheets, you will need to add seven blank sheets to the document. The script is counting sheets from the left and deleting the seventh sheet by position, so move the sheets you want to keep all the way to the right. Something kind of like this:

The copy_delete trigger, that sheet will be duplicated and renamed with the day’s date, and Sheet1 will be wiped clean to start a new day.

The appliance_id script will then comb through that day’s data and compare the magnitude changes in each row to each of the appliance signatures on the Appliances sheet. It will create one new column for each appliance. The script basically begins by comparing the current change only. If the current change is within 2 amps of the current change on the appliance’s signature, it then goes on to compare each frequency which has a magnitude change greater than 1 on that appliance’s signature. If they are within the specified tolerance of each other (this can be changed in the variable “tolerance” on the appliance_id script (Line 104 in the Google script)), then the script will insert the power consumed (in kWh) for that particular sample in that row under that appliance’s column. Once it has been designated as “on”, it simply looks for the current to drop by the amount in the appliance’s signature to determine it is “off”. Total power consumed by each appliance is accumulated and placed in row 3 of that appliance’s column. After the script has run, that day’s data will look something like this:

Looking at row 3, we have the total number of hours in column A, power consumed in kWh for phases A and B in columns B&M, and the power consumed by each appliance in columns from X onward.

Finally, the getDailyTotal script will run and will copy these totals over to our DailyLog page. It should look something like this:

There are a couple of variables in the getDailyTotal script that you’ll want to consider. The first is the cost variable, which you’ll need to define as the cost/kWh of power from your provider. The second is the days2keep variable, which is the number of days of data you want to keep. Google Sheets allows a maximum of 5 million cells in a document (Google Drive Support), so you won’t be able to store them indefinitely. This is given a value of 7 in the code above to store 7 days.

As you come up with new and creative ways to make calculations, move data more efficiently, or create charts and graphs to impress your friends, please share your ideas! (Don’t forget to move those new sheets to the right!)

Current Transformers installed on home's main power source.

Code

//  1. Enter sheet name where data is to be written below
        var SHEET_NAME = "Sheet1";

//  2. Run > setup
//
//  3. Publish > Deploy as web app
//    - enter Project Version name and click 'Save New Version'
//    - set security level and enable service (most likely execute as 'me' and access 'anyone, even anonymously)
//
//  4. Copy the 'Current web app URL' and post this in your form/script action
//
//  5. Insert column names on your destination sheet matching the parameter names of the data you are passing in (exactly matching case)

var SCRIPT_PROP = PropertiesService.getScriptProperties(); // new property service

// If you don't want to expose either GET or POST methods you can comment out the appropriate function
function doGet(e){
  return handleResponse(e);
}

function doPost(e){
  return handleResponse(e);
}

function handleResponse(e) {
  // shortly after my original solution Google announced the LockService[1]
  // this prevents concurrent access overwriting data
  // [1] http://googleappsdeveloper.blogspot.co.uk/2011/10/concurrency-and-google-apps-script.html
  // we want a public lock, one that locks for all invocations
  var lock = LockService.getPublicLock();
  lock.waitLock(30000);  // wait 30 seconds before conceding defeat.

  try {
    // next set where we write the data - you could write to multiple/alternate destinations
    var doc = SpreadsheetApp.openById(SCRIPT_PROP.getProperty("key"));
    var sheet = doc.getSheetByName(SHEET_NAME);

    // we'll assume header is in row 1 but you can override with header_row in GET/POST data
    var headRow = e.parameter.header_row || 1;
    var headers = sheet.getRange(1, 1, 1, sheet.getLastColumn()).getValues()[0];
    var nextRow = sheet.getLastRow()+1; // get next row
    var row = [];
    // loop through the header columns
    for (i in headers){
      if (headers[i] == "Timestamp"){ // special case if you include a 'Timestamp' column
        row.push(new Date());
      } else { // else use header name to get data
        row.push(e.parameter[headers[i]]);
      }
    }
    // more efficient to set values as [][] array than individually
    sheet.getRange(nextRow, 1, 1, row.length).setValues([row]);
    // return json success results
    return ContentService
          .createTextOutput(JSON.stringify({"result":"success", "row": nextRow}))
          .setMimeType(ContentService.MimeType.JSON);
  } catch(e){
    // if error return this
    return ContentService
          .createTextOutput(JSON.stringify({"result":"error", "error": e}))
          .setMimeType(ContentService.MimeType.JSON);
  } finally { //release lock
    lock.releaseLock();
  }
}

function setup() {
    var doc = SpreadsheetApp.getActiveSpreadsheet();
    SCRIPT_PROP.setProperty("key", doc.getId());
}

function Copy_delete() {
  var spreadsheet = SpreadsheetApp.getActive();
  spreadsheet.setActiveSheet(spreadsheet.getSheetByName('Sheet1'), true);
  spreadsheet.duplicateActiveSheet();
  spreadsheet.setActiveSheet(spreadsheet.getSheetByName('Sheet1'), true);
  var tz = spreadsheet.getSpreadsheetTimeZone();
  var sheets = spreadsheet.getSheets();
  var date = Utilities.formatDate(new Date(), tz, 'MM-dd-yyyy');
  sheets[1].setName(date);  // Rename second sheet
  var LastRow = spreadsheet.getLastRow();
  var rowString = "4:"+LastRow;
  spreadsheet.getRange(rowString).activate();
  spreadsheet.getActiveSheet().deleteRows(spreadsheet.getActiveRange().getRow(), spreadsheet.getActiveRange().getNumRows());
  
  //deleting the data causes reference errors in the formulas in row 3, these lines restore them
  spreadsheet.getRange('A3').setFormula('=sum(-1*A4,INDEX(A4:A, COUNT(A4:A)))*24');
  spreadsheet.getRange('B3').setFormula('=average(B4:B)*A3*120/1000');
  spreadsheet.getRange('M3').setFormula('=average(M4:M)*A3*120/1000');
};


function appliance_id () {
  var spreadsheet = SpreadsheetApp.getActive();
  var last = spreadsheet.getSheets().length; //index of last sheet
  var sheet = spreadsheet.getSheets()[1]; //sheet with yesterday's data that we will be analyzing
  var appliances = spreadsheet.getSheetByName("Appliances"); //sheet with appliance signatures
  var LastApp = appliances.getLastRow(); //number of appliances
  var sigRange = appliances.getRange('A2:W'+LastApp); //data range of appliance signatures
  var sigs = sigRange.getValues(); //this creates 2 dimension array of appliance signatures
  var LastRow = sheet.getLastRow(); //number of rows in yesterday's data
  var dataRange = sheet.getRange('A4:W'+LastRow); //data range of yesterday's data
  var data = dataRange.getValues(); //create 2 dimensional array of yesterday's data
  var tolerance = .3; //how close harmonic deltas must be to signature to match appliance
  
  for (i=0; i<LastApp-1; i++){ //loop for each appliance on appliance sheet, i will be row number on appliance sheet
    sheet.insertColumnsAfter(sheet.getLastColumn(),1); //add new column to data sheet for this appliance
    var col = sheet.getLastColumn()+1; //new column number
    sheet.getRange(1,col).setValue(sigs[i][0]); //add the appliance name to new column
    var flag = 0; //flag variable will be 0 for off and 1 for on
    var totpower = 0; //this variable will accumulate total power used by appliance
    for (j=2; j<=LastRow-4; j++){ //loop for each row of data, j will be row number on appliance sheet
      var Acurrent_delta = data[j][1]-data[j-2][1]; //A phase current change
      var Bcurrent_delta = data[j][12]-data[j-2][12]; //B phase current change
      if (flag==0 && Math.abs(Acurrent_delta-sigs[i][1])<2 && Math.abs(Bcurrent_delta-sigs[i][12])<2) { //check current change and see if it's within 2 amps of this appliances signature
        flag = 1; //if so, appliance may have turned on, so set flag to 1
        for (k=1; k<23; k++){ //after matching current, then check harmonics, k will represent column numbers for both sheets
          if (sigs[i][k]>1) { //only test the magnitude change if it's greater than 1, otherwise noise is too much
            var magdelta = data[j][k]-data[j-2][k]; //magnitude change of harmonic being tested 
            if (Math.abs(sigs[i][k]-magdelta)>tolerance*sigs[i][k]) { //tests the magnitude change, if more than tolerance from signature sets to 0. Adjust tolerance to your taste
              flag = 0;
            }
          }
        }
      }
      var time = (data[j][0]-data[j-1][0])/3600000; //calculates the time in hours from last sample
      var kwh = time*(sigs[i][1]+sigs[i][12])*120*flag/1000; //calculates the kWh of this sample
      if (flag==1 && Math.abs(Acurrent_delta+sigs[i][1])<2 && Math.abs(Bcurrent_delta+sigs[i][12])<2) { //if flag is already 1, check for negative current change to see if appliance turned off
          flag = 0;
        }  
     sheet.getRange(j+4,col).setValue(kwh); //add kWh for this sample to appropriate cell
     totpower+=kwh; //accumulate total kWh
     
    }
    sheet.getRange(3,col).setValue(totpower); //add total kWh consumed by appliance at top of appropriate column
  }
}
  
function getDailyTotal() {
  var spreadsheet = SpreadsheetApp.getActive();
  var sheet = spreadsheet.setActiveSheet(spreadsheet.getSheetByName('DailyLog'), true);
  var yesterday_data = spreadsheet.getSheets()[1];
  var LastRow = sheet.getLastRow()+1;
  var date = yesterday_data.getName();
  var Apow = yesterday_data.getRange('B3').getValue();
  var Bpow = yesterday_data.getRange('M3').getValue();
  var cost = .097; //this should be the cost/kWh for your utility company
  var days2keep = 7; //this is how many days of data you wish to keep
  sheet.getRange('A'+LastRow).setValue(date);
  sheet.getRange('B'+LastRow).setValue(Apow);
  sheet.getRange('C'+LastRow).setValue(Bpow);
  sheet.getRange('D'+LastRow).setValue(Apow+Bpow);
  sheet.getRange('E'+LastRow).setValue((Apow+Bpow)*cost);
  
  //appliance totals
  sheet.getRange('F'+LastRow).setValue(yesterday_data.getRange('X3').getValue());
  sheet.getRange('G'+LastRow).setValue(yesterday_data.getRange('Y3').getValue());
  sheet.getRange('H'+LastRow).setValue(yesterday_data.getRange('Z3').getValue());
  //likewise add a row like this for each appliance
  
  spreadsheet.setActiveSheet(spreadsheet.getSheets()[days2keep]);
  spreadsheet.deleteActiveSheet();
 
}

// This #include statement was automatically added by the Particle IDE.
#include <EmonLib.h>

#include "math.h"

double IrmsA, IrmsB, lastIrmsA, lastIrmsB, diff;
const int A=0;  //analog channel for phase A
const int B=1;  //analog channel for phase B
const int samples=1024; //number of samples to collect for FFT
const int harm=10; //number of harmonics to store
const int sampling_freq=4096; //sampling frequency
const int base_harm=20; //lowest frequency to record
const int pause=5000; //amount of time in milliseconds to pause between each sample; recommend at least 5000
int res = sampling_freq/samples; //resolution (how many Hz are represented by each index)
int step = (base_harm/res); //used to grab harmonics in for loop

float current1[samples], current2[samples], imag1[samples], imag2[samples]; //arrays for FFT
float magA[harm], magB[harm];   //array of magnitudes from most recent FFT

unsigned int period;    //sampling period
unsigned long microseconds; 

EnergyMonitor emon1;
EnergyMonitor emon2;

void setup() {
    Serial.begin(115200);
    period=round(1000000*(1.0/sampling_freq));  //calculate period based on frequency

    Particle.variable("CurrentA", IrmsA); //exposes current data to Particle cloud
    Particle.variable("CurrentB", IrmsB);

    emon1.current(A,222); //the second parameter in this function is used to calibrate to your specific current transformer/burder resistor combo. You may want to use a clamp on meter to verify your actual current draw so your power usage is accurate, otherwise you may have inaccurate results.
    emon2.current(B,97);//the second parameter in this function is used to calibrate to your specific current transformer/burden resistor combo. You may want to use a clamp on meter to verify your actual current draw so your power usage is accurate, otherwise you may have inaccurate results.
}

void loop() {
    //collect samples for FFT

	for (int i=0; i<samples; i++){
	    microseconds=micros();
	    current1[i]=analogRead(A);
	    current2[i]=analogRead(B);
	    imag1[i]=0;
	    imag2[i]=0;

	    while(micros() < (microseconds+period)){
	        
	    }
	}


    //Run the FFT function (direction, power of 2, real array, imag array)

    FFT(1,log2(samples),current1,imag1);
    FFT(1,log2(samples),current2,imag2);

    //compute magnitudes
  	for (int i=1;i<=harm;i++){
        magA[i-1]=sqrt(current1[step*i]*current1[step*i]+imag1[step*i]*imag1[step*i]);
        magB[i-1]=sqrt(current2[step*i]*current2[step*i]+imag2[step*i]*imag2[step*i]);
    }

    //calculate RMS current
    IrmsA = emon1.calcIrms(2000);
    IrmsB = emon2.calcIrms(2000);    

    //Convert magnitudes to strings to send to Google Sheets
    String tIrmsA = String(IrmsA,2);
    String A_1 = String(magA[0],2);
    String A_2 = String(magA[1],2);
    String A_3 = String(magA[2],2);
    String A_4 = String(magA[3],2);
    String A_5 = String(magA[4],2);
    String A_6 = String(magA[5],2);
    String A_7 = String(magA[6],2);
    String A_8 = String(magA[7],2);
    String A_9 = String(magA[8],2);
    String A_10 = String(magA[9],2);
   
    String tIrmsB = String(IrmsB,2);
    String B_1 = String(magB[0],2);
    String B_2 = String(magB[1],2);
    String B_3 = String(magB[2],2);
    String B_4 = String(magB[3],2);
    String B_5 = String(magB[4],2);
    String B_6 = String(magB[5],2);
    String B_7 = String(magB[6],2);
    String B_8 = String(magB[7],2);
    String B_9 = String(magB[8],2);
    String B_10 = String(magB[9],2);

    //This event publishes data to Google Sheets

    Particle.publish("GenericWebhookName","{\"IrmsA\":\"" + tIrmsA + "\",\"A1\":\"" + A_1 + "\",\"A2\":\"" + A_2 + "\",\"A3\":\"" + A_3 + "\",\"A4\":\"" + A_4 + "\",\"A5\":\"" + A_5 + "\",\"A6\":\"" + A_6 + "\",\"A7\":\"" + A_7 + "\",\"A8\":\"" + A_8 + "\",\"A9\":\"" + A_9 + "\",\"A10\":\"" + A_10 + "\",\"IrmsB\":\"" + tIrmsB + "\",\"B1\":\"" + B_1 + "\",\"B2\":\"" + B_2 + "\",\"B3\":\"" + B_3 + "\",\"B4\":\"" + B_4 + "\",\"B5\":\"" + B_5 + "\",\"B6\":\"" + B_6 + "\",\"B7\":\"" + B_7 + "\",\"B8\":\"" + B_8 + "\",\"B9\":\"" + B_9 + "\",\"B10\":\"" + B_10 + "\"}",5,PRIVATE);
   
    delay(pause);   
    
}

//FFT function from http://paulbourke.net/miscellaneous/dft/
short FFT(short int dir, int m, float *rx, float *iy) {
	
	int n, i, i1, j, k, i2, l, l1, l2;
	float c1, c2, tx, ty, t1, t2, u1, u2, z;

	/* Calculate the number of points */
	n = 1;
	for (i=0;i<m;i++) 
		n *= 2;

	/* Do the bit reversal */
	i2 = n >> 1;
	j = 0;
	for (i=0;i<n-1;i++) {
		if (i < j) {
			tx = rx[i];
			ty = iy[i];
			rx[i] = rx[j];
			iy[i] = iy[j];
			rx[j] = tx;
			iy[j] = ty;
		}
		k = i2;
		while (k <= j) {
			j -= k;
			k >>= 1;
		}
		j += k;
	}

	/* Compute the FFT */
	c1 = -1.0; 
	c2 = 0.0;
	l2 = 1;
	for (l=0;l<m;l++) {
		l1 = l2;
		l2 <<= 1;
		u1 = 1.0; 
		u2 = 0.0;
		for (j=0;j<l1;j++) {
			for (i=j;i<n;i+=l2) {
				i1 = i + l1;
				t1 = u1 * rx[i1] - u2 * iy[i1];
				t2 = u1 * iy[i1] + u2 * rx[i1];
				rx[i1] = rx[i] - t1; 
				iy[i1] = iy[i] - t2;
				rx[i] += t1;
				iy[i] += t2;
			}
			z =  u1 * c1 - u2 * c2;
			u2 = u1 * c2 + u2 * c1;
			u1 = z;
		}
		c2 = sqrt((1.0 - c1) / 2.0);
		if (dir == 1) 
			c2 = -c2;
		c1 = sqrt((1.0 + c1) / 2.0);
	}

	/* Scaling for forward transform */
	if (dir == 1) {
		for (i=0;i<n;i++) {
			rx[i] /= n;
			iy[i] /= n;
		}
	}

	return(0);
}

Credits

Terabull

1 project • 1 follower

Keith Snyder

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Home Power Monitor

Home Power Monitor

Things used in this project

Hardware components

Software apps and online services

Story

Overview

Google SpreadSheet Setup

The Google Sheets Script

The Webhook

The Firmware

Additional Sheet Setup

Concluding Remarks

Schematics

Voltage Divider Cicuit

Photon Schematic

Code

Google Sheets JavaScript

Photon Program

Credits

Terabull

Keith Snyder

Comments

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