In my last post I showed you how to configure the Seeeduino LoRaWAN module to connect to TheThingsNetwork (TTN). But this is only half the rent. You want to do something with the data the node sends, right? This post will show you how you can log the messages from the node to a Google Spreadsheet. It is relatively easy to do but not save, since it lacks security features.

In the first post of this series we had a look at a very specific LoRaWAN module, the Seeeduino LoRaWAN. We configured the module as well as TheThingsNetwork to allow the module to send data to the network. But TTN is just the network infrastructure. It doesn’t allow you to do anything with the data the nodes sends you beyond having a quick peek. Now I want to to show you how you can build a simple system which logs the data in a spread sheet. To get started you need:

• Configured Seeeduino LoRaWAN module (read more)
• Configured TheThingsNetwork account (read more)
• Google Docs account

 

Setting Up the Spreadsheet

Log into your Google Docs account and create an new Spreadsheet

Give the Spreadsheet a meaningful name, e.g. LoRaLogger

Then go to Tools > Script Editor…

Replace the few lines of code with the code below:

// 2017 by Daniel Eichhorn, https://blog.squix.org
// Inspired by https://gist.github.com/bmcbride/7069aebd643944c9ee8b
// Create or open an existing Sheet and click Tools > Script editor and enter the code below
// 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

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) {
  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 headers = sheet.getRange(1, 1, 1, sheet.getLastColumn()).getValues()[0];

    var nextRow = sheet.getLastRow()+1; // get next row
    var row = [];
    var headerRow = [];
    // loop through the header columns
    var jsonData = JSON.parse(e.postData.contents);
    
    headerRow.push("jsonData.app_id");
    headerRow.push("jsonData.dev_id");
    headerRow.push("jsonData.hardware_serial");
    headerRow.push("jsonData.port");
    headerRow.push("jsonData.counter");
    headerRow.push("jsonData.payload_raw");
    headerRow.push("jsonData.payload_decoded");
    headerRow.push("jsonData.metadata.time");
    headerRow.push("jsonData.metadata.frequency");
    headerRow.push("jsonData.metadata.modulation");
    headerRow.push("jsonData.metadata.data_rate");
    headerRow.push("jsonData.metadata.coding_rate");
    headerRow.push("jsonData.metadata.downlink_url");
    for (var i = 0; i < jsonData.metadata.gateways.length; i++) {
      var gateway = jsonData.metadata.gateways[i];
      headerRow.push("gateway.gtw_id");
      headerRow.push("gateway.timestamp");
      headerRow.push("gateway.channel");
      headerRow.push("gateway.rssi");
      headerRow.push("gateway.snr");
      headerRow.push("gateway.latitude");
      headerRow.push("gateway.longitude");
      headerRow.push("gateway.altitude");
    }
    sheet.getRange(1, 1, 1, headerRow.length).setValues([headerRow]);
    
    row.push(jsonData.app_id);
    row.push(jsonData.dev_id);
    row.push(jsonData.hardware_serial);
    row.push(jsonData.port);
    row.push(jsonData.counter);
    row.push(jsonData.payload_raw);
    var raw = Utilities.base64Decode(jsonData.payload_raw);
    var decoded = Utilities.newBlob(raw).getDataAsString();
    row.push(decoded);
    row.push(jsonData.metadata.time);
    row.push(jsonData.metadata.frequency);
    row.push(jsonData.metadata.modulation);
    row.push(jsonData.metadata.data_rate);
    row.push(jsonData.metadata.coding_rate);
    row.push(jsonData.metadata.downlink_url);
    for (var i = 0; i < jsonData.metadata.gateways.length; i++) {
      var gateway = jsonData.metadata.gateways[i];
      row.push(gateway.gtw_id);
      row.push(gateway.timestamp);
      row.push(gateway.channel);
      row.push(gateway.rssi);
      row.push(gateway.snr);
      row.push(gateway.latitude);
      row.push(gateway.longitude);
      row.push(gateway.altitude);

    }

    // 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());
}

 

Goto Run > Setup

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)
• Copy the ‘Current web app URL’ and post this in your form/script action

Give permissions to the script:

Copy the URL:

 

Setting Up TTN

Now we have to tell TheThingsNetwork where to write the data to. Go to your application in the TTN console and click on the “Integration” button. Then select the HTTP Integration:

Now paste the URL you earlier copied from the Google Spreadsheet to the URL form field and set the other fields like here:

Leave the other fields as they are and click on “Add integration”. There you go! Now plug in your configured Seeeduino (or any other TTN node) and you’ll get a new row for each message!

 

Summary

I hope you found this really easy and it worked for you. We created a simple IoT application which can log (sensor) data and node meta data. If you know how to write app script you can easily extend the code by sending push notifications to your cell phone in special situations. Or you can add a chart to the spread sheet analyzing signal quality, etc.

One word of warning: the current script is not really save, anyone knowing the URL can send data to your spread sheet. We could improve it by adding an authentication header (in the currently) empty TTN form field and check it in our App script code.

Do you have questions about this post? Go over to https://support.squix.org and place it there so everyone can profit!