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Checking fluctuating variables using thresholds, the smart way.

So, here’s the drill. In CS, we frequently need to check a variable compared to a predefined threshold.

Typical uses include checking the light level in a room and controlling the lights when it exceeds or goes below a certain threshold (the same can be done with temperature, essentially like a thermostat), checking the negative votes (vote-downs) for a post and removing it if it exceeds a threshold, e.t.c.

That’s usually easy to do programatically:

if(downvotes > VOTES_THRESHOLD)
{
remove_vote();
}

However, when you work with fluctuating variables, it’s harder to do a proper check. This is a common problem with sensor values, because they tend to … Continue Reading

PMH: State of the überness

For those of you who know me, you already know I’m really psyched about the Arduino platform. One of the things I’m also psyched is home automation. Not the crapy, oldschool home automation we all know and disregard, but the cool, shiny home automation. The kind of thing that you see in Star Trek and go “ooooooooooooooooooh!”. You know, like “Computer, adjust my temperature to 23.56 degrees, unless it’s Sunday with a full moon. Oh, and bring me a burger. And a beer.”, followed by “*bleep*OK*bleep*” and a tasty burger-beverage combination.

The main system I’m working on, mainly as part of … Continue Reading

Clang + Arduino = ♥

So… Clang.

Anyone who codes in C, C++ or Obj-C should know it. If you don’t, read about it. Seriously, stop reading this post and google it. Check my video to see a quick overview of its features.

Now you should know that Clang (+LLVM) is awesome. It’s steadily shaking the still waters of C compilers, and in my opinion, gradually replacing GCC as the de-facto C compiler. I’d like to talk a bit about Clang’s syntax analysis. Let’s assume this sample code:
#include<stdio.h>

int main(void)
{
int myVar = 5
int myVar2 = myVar;
int hello1 = 4;
Continue Reading

FOSSCOMM 2012

It’s been a long time since i last updated my blog, and I hope it won’t take me so long until the next time.

I’d like to start blogging again by mentioning the last open source conference I attended, FOSSCOMM 2012, which took place at my hometown, Serres, Greece. For those unaware, FOSSCOMM is the biggest open source conference in Greece, where people and communities from all over Greece meet annually to exchange ideas and news.

First of all, the conference was very nice, and i congratulate this year’s organizing committee. They did a great job, and the few minor issues that … Continue Reading

We’re on Hack a Day!

Where by ‘we’, I mean P-Space, the local hackerspace in Patras. Recently, I designed an (open source, ofc) system to control our door for entry, using RFID tags an a remote controller. Everyone liked it, so we installed it and I set off to document it on GitHub. We aptly named it Jarvis, after Edwin Jarvis.

To put it simply, Jarvis consists of a remote control that tells the computer to open the door when pressed, the door controller that reads the RFID tags and send the information to the computer, and the computer that validates the RFID information, … Continue Reading

Guess who’s a Growl developer

If you’re a mac user, you might have heard about Growl, perhaps you’re even using it. Those of you who know me might have heard me rant about how its greatness. It’s simply such a well thought-out, designed and developed software.

For those of you who have never heard of it, Growl is a notification system and framework for OS X. It’s highly configurable, yet easy to do so. The user can choose the notification style, the position of notification on the screen, set different notification styles and behavior for each program, etc. It’s even possible to have the notification emailed … Continue Reading

Arduino Pro Mini shields!

I’m proud to introduce my latest Arduino-related project. For the past year, I’ve been using the Arduino Pro Mini from Sparkfun extensively, and I’ve come to love it for its small size and awesome XBee connectivity. Since I’m frequently using relays, I’ve been making lots of relay boards, and every time I needed to add or remov a relay to a project, it’s been kind of a pain in the ass, so I devised a smart solution.

First of all, I need to make a small introduction. Using the Stackable Headers from Sparkfun, I made it … Continue Reading

Making coffee with Arduino

No, this will not be another serious blog post. It will, however, be an exercise in ingenuity and thinking outside the box. Most of all, I’m writing this because people requested it on Twitter :P

Long story short, a friend of mine and me wake up at my place after a long night of drinking, and start making coffee, and more specifically, the Greek favorite, Frappé. This includes shaking the coffee into a shaker, or using a device like this to stir the coffee. But the batteries were dead, and I had no replacements!!!!! We were left with 3 … Continue Reading

Long time no write

So, yeah, I’ve been pretty busy in a while, what with my exams, work, etc, but I am finally proud to announce something I’ve been secretly working on. That is, my article on the last issue of Linux Inside! For those who’ve never heard about it, Linux Inside is THE linux-related magazine in Greece, by Dimitris Kalamaras, who’s done a great job educating people on open source, and creating a magazine targeted to everyone, geek or not :) First things first, I’d like to thank him for giving me the opportunity to write about Arduino (the article is … Continue Reading

ellak conference 2011, Day 1

As I came home, I realized I had to write something about my first day on on the ellak conference. Not only was it nice to compare it to this year’s FOSSCOMM, and look at the pros and cons of each, some things I consider we did better, and things they managed better than us, but about the experience as well.

As chance would have it, I was the only one left in charge of the arduinoproject.gr booth, since the 2 other guys who were supposed to come couldn’t. For those who don’t know, arduinoproject.gr is a work-in-progress in creating a … Continue Reading

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