Skip to main content

DIY home automation v2

Previously I set up a simple home automation system for controlling outlets at home. So far I've used the system for controlling various lights at our home. I've been satisfied with oulet controlling via browser but I wanted something more.

Objective


I had a idea of temperature and humidity monitoring via Raspberry Pi. I was already browsing for electronics components needed for building a system with sensors but buying single components seemed a bit expensive and I would also have to actually connect all the components to RPi and write the code to read the sensor data.

Mainly because of the price the components I started looking for a pre-built system with the preferred sensors. Almost immediately I came across Proove's sensor that has indoor and outdoor temperature sensors and a indoor humidity sensor. Best part of the pre-built system is that it's already compatible with TellStick system that I used for controlling outlets.

I decided to buy the pre-built sensor system. I just needed to figure out how to read the sensor values and display them on the same UI that I built for controlling outlets.

Sensor data


The sensor system is nice in the way that it automatically sends it's sensor data in some sort of broadcast and the TellStick Duo automatically receives all the data. Something's also flaky with the sensor system because it sends sensor data from a bunch of sensors. Most of the sensor data is just invalid data and it's up to the user to determine which sensors are sending valid data.

tdtool --list-sensors

Reading and decyphering sensor data


Decyphering which sensors were sending valid data was a manual process of viewing the sensor data and comparing that to the values displayed on the sensor system's lcd screen. I managed to figure out that my system sends outdoor temperature with sensor id 135 and indoor temperature and humidity with sensor id 136.

Reading sensor data via python


The telldus-core library that's used to control the outlets also provides functionality to read sensor data. It was just a matter of figuring out how to read the data and I found a good example from github.

Result


As previously the REST API is written with Python and it uses the C-library to communicate with TellStick Duo and the UI functionality is written with JavaScript. Reading the sensor data and viewing it in the UI is implemented in the same code base as the outlet controller.

I just added a new endpoint /sensors that returns sensor data for the two sensors and added some UI functionality to read and view the data.

Sensor data above outlet control


Few things to know about the code

 

Because the sensor system sends invalid data with bogus id's I extracted the sensors id's to their own module sensorconf.py that defines the id's for indoor and outdoor sensors 

The UI has names for the different sensor values but I didn't separate them from the logic but instead hard coded them.
Labels:

Popular posts from this blog

Simple code: Readability

Readability, understandability, two key incredients of great code. Easier said than done, right? What one person finds easy to read and understand another one finds incomprehensible. This is especially true when programmers have different levels of understanding on various subjects e.g. object oriented vs. functional or Node.js vs. Java. Even though there are obvious differences between paradigms and programming ecosystems there are some common conventions and ways to lower the barrier. Different approaches It's natural that in programming things happen sequentally e.g. you can have a list of objects and you need to do various things to the list like filter some values out and count a sum of the remaining objects based on some property. With the given list const stories = [   {name: "authentication", points: 43},   {name: "profile page", points: 11},   {name: "shopping cart", points: 24},   {name: "shopping history", points: 15},   {name: &qu
Read more

Sharing to help myself

It's been a while since my last post but I have a good excuse. I've been in a new customer project (well new for me) for two months now and have absorbed a lot of new information on the technology stack and the project itself. This time I'll be sharing a short post about sharing code and how it can help the one who's sharing the code. I'll be giving a real life example of how it happened to me. My story Back when I was implementing first version of my simple-todo REST-service I used Scala and Play framework for the service and specs2 for testing the implementation. Since then I've done a few other implementations of the service but I've continued to use specs2 as a testing framework. I wrote about my implementation and shared the post through various services and as a result someone forked my work and gave me some pointers on how I could improve my tests. That someone was Eric Torreborre  the man behind specs2 framework. I didn't take his ref
Read more

Simple code: Immutability

Immutability is a special thing that in my mind deserves a short explanation and praise. If you're familiar with functional programming you surely recognice the concept of immutability because it's a key ingredient of the paradigm. In the world of object oriented programming it's not as used and as easy to use approach but there are ways to incorporate immutability to parts of the code and I strongly suggest you to do so. Quick intro to immutablity The basic idea of immutability is unchangeable data.  Lets take a example. We have a need to modify a object's property but because the object is immutable we can't just change value but instead we make a copy of the object and while making the copy we provide the new value for the copy. In code it looks something like this. val pencil = Product(name = "Pencil", category = "Office supply") val blackMarker = pencil.copy(name = "Black marker") The same idea can be applied in functions and metho
Read more