IOT device #2/100 – IOT Clock

Here is my final version of this simple internet enabled clock. The case is printed out of PETG. There is a lot of room for improvement, but I like to keep the scope simple on my projects and this works perfect as a clock.

The source code and CAD files are here.


Simple IOT Clock

I built a cool little clock using an ESP8266 and a dot matrix display I got for $8. The total cost will probably be under $20.

The clock uses NTP to sync the time, then updates the second ticker on the bottom every 2 seconds. When the minute changes it updates the entire display.

It didn’t take too long as I used code by others (NTP client, WiFi Manager, MD_MAX72xx animations).

Code is here.


Improving water proofing in my Weather Station

We had a few severe thunderstorms where I live and I the wind and rain caused damage to my electronics in my outdoor weather station.


The weather station is waterproof if there is just light rain, but strong winds will blow water into the Stevenson Screen damaging the electronics.

I have decided to seal off the electronics as much as possible – hopefully this new construction will be more robust.

Single Page Responsive Web Apps using JavaScript , jQuery and Bootstrap

The ThingSpeak Web Page does not allow you to pull historical data from your channel, plus simple things like converting Absolute Pressure to Mean Sea Level Pressure require running Matlab Scripts.

I decided to create a single page web app that had the features I required. I ended up with the following features:

  • Cross platform/browser
  • Responsive (usable on my 24″ monitor, tablet and phone)
  • Customizable graphs (color, type etc)
  • Ability to select multiple days/weeks
  • Ability to select last minute/hour/day
  • Sea Level Pressure Conversion Built in
  • Auto summation for rain graphs by interval
  • Auto update graphs to get latest data

The web app needs to request data from which is a different domain to the domain where the web app is hosted. To do this I created a route in Ktor which accepts a JSON request and responds with the contents of the request.

post("/getJSON") {
            val thisReq = call.receive()
            val req = khttp.get(thisReq.url)
            if (req.statusCode == 200) {
            } else {
                call.respond(json { "success" to "false" })

I understand this could be potentially abused as this is a effectively an anonymous router, but I am not worried just yet.

To access this in JavaScript:

var thingSpeakQuery = `${feedID}/feeds/last.json`;
var getJSONThingSpeak = {
	"url": thingSpeakQuery
	type: "POST",
	url: "/getJSON",
	data: JSON.stringify(getJSONThingSpeak),
	contentType: "application/json; charset=utf-8",
	dataType: "json",
	success: function (element) {
		// code here to handle data
	failure: function (errMsg) {
	// catch internal server error, this happens when the server can't pass the JSON data,
        // or the ThingSpeak ID is invalid
	statusCode: {
		500: function () {
			console.log("Query returned no data.");

Here I am using an AJAX function to get the latest data from the specified ThingSpeakID.

The rest of the web is pretty much standard JavaScript and relies heavily on jQuery to update the web page. The JSON data structures get pretty complicated. In order to debug/test the code while I was writing it I made the returned JSON data a global variable and used Chromium’s Dev Tools to write the code.

For example here where are looping through all the Charts and adding the ThingSpeak data: (element) {
                // loop over each data field in ThingSpeak data
                for (var k = 0; k < chartList.length; k++) {
                    // store as a tmp string, as not to change with 'k'
                    var tmp = k + 1;
                        x: moment(,
                        y: parseFloat(["field" + tmp.toString()])
// snipped

The above would be very difficult to write by hand, or get working by trial and error. Being able to run the code in the browser and make things instantly change was actually a lot of fun.

JavaScript is fast becoming my favorite language, not due to it’s technical merits but due to the fact it allows we to be vendor agnostic. I can run my code on my FreeBSD/Linux/Android/Windows/Mac/iPhone hardware.

The coolest feature, is the auto update feature. It allows me to leave the browser window open on my computer and have a live stream graph of my weather station without having to continuously hit the refresh button!

It’s pretty simple, it just uses a JavaScript interval function:

setInterval(function () {
    // This will be executed every 60 seconds
    }, 60000);

You can use the web app here.


Simple Content Management System using Kotlin/JQuery/Ktor/MySQL

I wrote a simple Content Management System using JQuery, Kotlin and Ktor. I did this to learn more about JavaScript, MySQL and the webstack before moving on to learn a web framework (React).

There was a fair bit of JS code, and several routes that had to be created, but it wasn’t that difficult and only took two days.

The current system runs on my website ( and has a front end and backend that run as separate services.

You can view the source code here and here.


Weather Bot goes live

I re-wrote my weather bot completely in Kotlin and split the functionality into three parts:

  1. The back-end downloads RSS feeds and compares them against the user database, it sends the alerts to user’s mobiles
  2. The front-end adds users and handles verification
  3. The front-end administration panel allows for addition, deletion of users.

Both the front-ends are written using jQuery, Bootstrap, vanilla Javascript and Kotlin/ktor. They are both single page web apps and allow for all functions without page reload.

Here is the sign up page on my website:


Here is the admin interface:


The database functions are handled using data classes and SQL objects using a SQL DSL for Kotlin caused Exposed.

Below is an example of the object classes, data classes and a function required to return a list of user objects. This code is used to return a list of users to the admin interface.

The Kotlin SQL DSL makes the programming of very complicated data structures a breeze.

object users : Table() {
    val id = integer("id").autoIncrement().primaryKey() // Column
    val name = varchar("name", length = 150) // Column
    val country = varchar("country", length = 150) // Column
    val state = varchar("state", length = 150) // Column
    val mobile = varchar("mobile", length = 50) // Column
    val opt1 = varchar("opt1", length = 50).nullable() // Column
    val opt2 = varchar("opt2", length = 50).nullable() // Column


object userkeywords : Table() {
    val id = integer("id").autoIncrement().primaryKey() // Column
    val uuid = integer("uuid").nullable()
    val keywords = varchar("keywords", length = 150) // Column

data class completeUser(
    val id: Int,
    val name: String,
    val country: String,
    val state: String,
    val mobile: String,
    val keywords: MutableList,
    val opt1: String,
    val opt2: String
fun getAllUsers(): MutableList {
    var returnedUsers = mutableListOf()
    transaction {
        SchemaUtils.create(users, userkeywords)
        val allKeywords = userkeywords.selectAll()
        for (user in users.selectAll()) {
            val thisUser = completeUser(
                id = user[],
                name = user[],
                country = user[],
                state = user[users.state],
                mobile = user[],
                opt1 = "NIL",
                opt2 = "NIL",
                keywords = mutableListOf()
            println("${user[]}: ${user[]}")
            for (k in allKeywords) {
                if (k[userkeywords.uuid] == user[]) {
                    val kw = k[userkeywords.keywords]

    return returnedUsers

To send this data in JSON it is very easy.

First “install” the GSON feature:

install(ContentNegotiation) {
        gson {

Then add the route:

get("/getUsers") {
    var theseUsers = getAllUsers()

Pretty braindead stuff really. Handling queries in JavaScript is also very easy (the following function adds all retrieved users to a drop down menu):

var getUserList = function() {
    type: "GET",
    url: "/getUsers",
    // The key needs to match your method's input parameter (case-sensitive).
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: function(data) {
      data.forEach(function(element) {
${} mobile: ${}`);
    failure: function(errMsg) {

As for the back-end, I had to write the API in Kotlin to connect to the Telstra API. I had to use khttp because ktor client can not set custom headers at the moment.

Here is an example of how it works:

//provision a number
val response =
      url = "",
      headers = mapOf("content-type" to "application/json","authorization" to "Bearer ${token}" , "cache-control" to "no-cache"),
            data = "{ \"activeDays\": 30 }")

// get/update API token
val payload = mapOf(
      "grant_type" to "client_credentials",
      "scope" to "NSMS",
      "client_id" to "xxx",
      "client_secret" to "xxx")

val response =
      url = "",
      headers = mapOf("Content-Type" to "application/x-www-form-urlencoded"),
      data = payload)

// send a message
val response =
      url = "",                  
      headers = mapOf("content-type" to "application/json",
      "authorization" to "Bearer ${token}"),
      data = ourJson.toString())

I had to setup a dummy route in ktor and use WireShark to sniff the packets to figure out which headers needed to be set before I could finally figure out how the system worked.

Thanks to Telstra for the free 1000 messages per month and thanks to the folks at Jetbrains for all their awesome libraries and products.