Friday, May 22, 2015

Internet of Things (IoT) with ESP8266 - Proof of Concept


Recently, I finished my first, usable IoT prototype on a breadboard. It is a simple unit, consisting of an LED (emulating a digital output) and a switch (emulating a digital input). Many of the IoT applications can be traced back to this simple application, so even if a particular application needs more than the capabilities of my prototype, the processes, methods, modules and practices described below are likely applicable to any IoT application/project.
The ESP8266-01 on a breadboard, complete with power supply and some simulated environment (LED, button).

Saturday, May 16, 2015

Installing Mosquitto for Use with ESP8266


I am working on a home automation project which required I installed Mosquitto, an open source MQTT broker, on my Raspberry Pi. Installation went smoothly, so a few minutes after first hearing about Mosquitto it was ready to be used on my RPi.

Next, I tested it by subscribing to topics and publishing messages from different SSH sessions, all without a problem.


When I configured my ESP8266 to communicate with this Mosquitto broker, it could not connect to it. Interestingly, my ESP8266 could successfully communicate a test broker on the internet at This was really weird, as usually stuff works locally and migrating to the internet things tend to break, not the other way around.

Looking through the logs I found the following errors:
May 12 12:01:47 dev mosquitto[2316]: New connection from
May 12 12:01:47 dev mosquitto[2316]: Invalid protocol "MQTT" in CONNECT from


A quick research on the internet revealed that I am not the only one with this problem, and that the root of the problem is that the version of Mosquitto that's in the debian wheezy repositories is not compatible with the version the ESP8266 uses.

The following steps need to be taken to correct the problem (taken from ):

wget sudo apt-key add mosquitto-repo.gpg.key

cd /etc/apt/sources.list.d/
sudo wget
sudo apt-get update
To display what version of Mosquitto is installed you can use the following:
sudo apt-cache search mosquitto
As soon as I restarted mosquitto the ESP8266 could connect to it with no problem.

Now the logs contain much friendlier messages:
May 12 19:05:37 dev mosquitto[3315]: New connection from on port 1883.
May 12 19:05:37 dev mosquitto[3315]: New client connected from as viktak (c1, k60).

Sunday, May 10, 2015

Fridge Magnets from your Own Photos


This is not a pure DIY project in the sense I also used a third party company to achieve my goal. Nevertheless, it's a fun and pleasant one if you like photography as I do (I am also a photographer). In this article I will describe a novel way of using your favorite photographs.

A sheet of my very own fridge magnets

Searching for the new stuff

I am currently in the process of organizing a photographic exhibition of my own photographs. While looking for printing services online I came across a few companies who do prints on special materials, like wood, leather, stone, etc. I immediately liked the idea of "jazzing up" the exhibition with some merchandise other than a catalog of the exhibits, but I wasn't very warm about pictures printed on, say, a piece of wood. After some more digging I found a German company called PicPack printing images on fridge magnets. The price also looked OK for a test run, so I decided to do a test run to see if the quality is up to my expectations.

Below I am going to share my experiences and thoughts with this test run. Also, had I read an article like this before I used the service I review here, I would have had much better results for the first try. So I hope this will be useful for some.