Turning the Raspberry Pi into a Wireless Access Point

Hi! Following my latest posts on how to get started with the Raspberry Pi "headless mode" and Using Bluetooth with the Raspberry Pi now I'll show how to turn the Raspberry Pi into a Wireless Access Point. Most of this post follows what is described here but I added a few more steps. Moreover, I ran into some troubles and had to do some troubleshooting. I used a D-Link DWA-140 Rangebooster N Adapter which contains a Ralink RT2870 chipset.

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 The process looks a little long but it can be done in under 10 minutes :) . Every time you need to edit or create some file (for example /etc/udhcpd.conf) among this process you can use "sudo nano /etc/udhcpd.conf".

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Installing Bluetooth tools in Raspberry Pi

Hi there!

Following my previous post on how to get started with the Raspberry Pi "headless mode" I'll now show you how to install the Bluetooth tools.

On the project that I'm working on right now I'll be using Bluetooth with the Raspberry Pi so that later I can connect to several devices via Bluetooth. For this purpose I have ordered some USB Bluetooth dongles from ebay and some HC-05 Bluetooth modules, also from ebay.

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The first thing to do is type "lsusb" in the terminal to see if your USB Bluetooth dongle is being recognized. As an example, the ones I ordered from ebay show up as:

Bus 001 Device 004: ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode)

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Headless start with the Raspberry Pi

Hi! Some time ago I made two posts about the the Raspberry Pi (Raspberry Pi has Arrived and First Impressions on the Raspberry Pi) and unfortunately since then it has been closed inside its box. I really wanted to do something with it but other projects always got in the way. Finally I'm doing a project where I'll use the Raspberry Pi and I hope to make some posts about Raspberry Pi stuff while I work on it. To begin I'll show you how to start playing with your Raspberry Pi without having to connect it to an external HDMI monitor or screen with RCA connector and using Ubuntu on your computer.

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The first thing to do is get yourself a 4GB (or greater) class 4 SD card. Branded cards are usually better and more trustful. If you have one, then its time to prepare the card to be used in the Raspberry Pi.

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How to install Chrome on Ubuntu 12.04

Hi! Today I'm just going to provide a very quick and easy tutorial on how to install Google Chrome browser in Ubuntu 12.04 Precise Pangolin.

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It's really, really easy. First go to this link and download the .deb package for you CPU (32-bit or 64-bit). Then open the terminal and get into your Downloads folder and enter the following command:

sudo dpkg -i google-chrome-stable_current*.deb

If you get some error regarding unmet dependencies you can fix them by entering:

sudo apt-get install -f

And that's it! Google Chrome will be installed in your system! :)

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Coursera: Interactive Programming with Python

Hi there! :) About two and a half months ago I found about the new trend in web education, the MOOCs. MOOC stands for Massive Open Online Course. Basically, there are a few sites where you can take lots of courses from top universities such as MIT, Stanford, Harvard, etc. The greatest thing is that it costs absolutely nothing to take the courses. They're FREE! :) I'm sure that these learning systems are starting a new era in higher education since now anyone with access to internet can have access to high quality courses.

So, after browsing through the lots of courses available and seeing which ones were about to begin, I decided to start with a course provided by Rice University on Coursera: Interactive Programming with Python. I already knew how to program in Python before the course but I knew there were still some details to master and some good practices to learn in applications with GUI and animations. Also, is there a better way to learn that than by making classic games like Pong or Asteroids? Guess not! :)

So, I'm going to make a short review on the course so that you can understand how it works and if you should take the course :)

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The course has weekly lectures that you can watch online whenever you want and at your own pace.

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How to install HeeksCAD in Ubuntu 12.04

Hi! In a previous post where I wrote about the CNC Software Toolchain for Linux I mentioned HeeksCAD, which is a great software to generate the toolpaths from the 3D models for CNC machining. Since I upgraded to Ubuntu 12.04 I started having some problems with the HeeksCNC plugin and some features like the pocketing and profile operations stopped working. I tried to reinstall it in Ubuntu 12.04 but then I found out that it wasn't a so straight forward process as with previous Ubuntu versions. As such, I decided to make a small tutorial on how to install it under Ubuntu 12.04 Precise Pangolin.

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So, the first trick is that you cannot install the official version from the official HeeksCAD git repository.

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The Hackerspace Movement: Mitch Altman at TEDxBrussels

Hi! Following my previous post about the eLab Makerspace Today I'm just going to share a video that I saw today and honestly think that everyone who loves learning, making, tinkering, should see (and everyone who doesn't should see it too!). It's a video about the history of Hackerspaces and the Maker movement that includes some valuable lessons about hacking yourself, about changing your life to do what you love. Some other messages rely on making ideas come true and how it is possible to make the "impossible" with only a few resources and a big "go for it" mentality. Basically it all comes down to three words: "Teaching. Learning. Sharing.".

Hope you liked it as much as I did! :)

Take care!

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The birth of eLab Hackerspace

Hi! Today I'll let you know about a Hackerspace that I have founded together with my friends João Duarte, Goncalo Pereira, Fábio Martins and Hugo Santos in September of 2011 inside the University of the Algarve. The electronics engineering department had been providing a room for students to do their projects for a few years but it had never got much use.

It all started with the Electronics Club some years ago which was founded by my friend Zé Luis (currently doing some cool stuff at his company, Metalideia) and some of his friends. After some years it changed name twice and became NEEST, then NOISE, but unfortunately only the names were changing and not much was being done, except keeping it "alive", which was also important. Otherwise the room would have been lost. We had been talking about how the space wasn't being properly used for a while and then we finally decided to go ahead and turn it into a real Hackerspace, eLab. As far as we know it's the first Hackerspace hosted inside a university in Portugal, having great benefits like free space, free internet and free electricity. Also, sometimes we get to borrow some tools from the electronics engineering department which is always handy.

We began by meeting once every week to clean everything, scavenge components from all the electronic devices that had been gathered throughout the years, put some shelves on the walls, organize all the components and tools and take out the trash.

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Then we had to make the Hackerspace rules, so that everyone can use the space in harmony.

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Pictobrowser, a great slideshow for Flickr and Picasa

Hi! When I was setting up this new version of "the BiT Bang Theory blog" in Blogger I had to make some choices. One of them was which free image hosting to use, Picasa Web Albums or Flickr? I ended up choosing Picasa Web Albums (if you're wondering why, check the link). With this choice, I had to make another one: which slideshow should I use? Well, I could just use the slideshows from Picasa but, honestly, they look very ugly and do not fit into the blog's color scheme. They should have added some options to customize them. After some searching through the web I found two slideshows that I really liked. The one I liked the most is the one featured on the title of this post: Pictobrowser.

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New Publication: Multi-scale cortical keypoints for realtime hand tracking and gesture recognition

Hi! This post is just to let you know that there is a new publication in the Publications page named Multi-scale cortical keypoints for realtime hand tracking and gesture recognition. It was presented in the 1st International Workshop on Cognitive Assistive Systems: closing the Action-Perception Loop, held in conjunction with IROS2012.

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Here's the abstract:

"Human-robot interaction is an interdisciplinary research area which aims at integrating human factors, cognitive psychology and robot technology. The ultimate goal is the development of social robots. These robots are expected to work in human environments, and to understand behavior of persons through gestures and body movements. In this paper we present a biological and realtime framework for detecting and tracking hands. This framework is based on keypoints extracted from cortical V1 end-stopped cells. Detected keypoints and the cells’ responses are used to classify the junction type. By combining annotated keypoints in a hierarchical, multi-scale tree structure, moving and deformable hands can be segregated, their movements can be obtained, and they can be tracked over time. By using hand templates with keypoints at only two scales, a hand’s gestures can be recognized."

If you wish you can download it in the Publications page or just click here.

Take care! :)

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Experimenting with vacuum molding

Hi there! This post is about a really simple way of making plastic parts for your projects. Have you ever heard of vacuum molding? It's a method to make a plastic mold of a piece by using heat and suction from a vacuum cleaner. You can easily replicate what I'm going to show you. You just need some wooden pieces to make a box like the one you'll see in the picture, a vacuum cleaner, a heat gun/electric heater/oven and some disposable plastic dishes.

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State of the Art in Intelligent Humanoid Robotics

Hi! This will not be my typical kind of post. I usually post about projects, tutorials, publications, etc. but this time I'm just going to share a video that shows the state of the art towards the development of Intelligent Humanoid Robotics. It's a great video and shows some of the great research that has been done with the iCub robot. I'm not just sharing a video because I'm being lazy, I'm sharing it because it shows the awesome work that has been done with an awesome robot and it deserves to be shared. This is not science fiction. This is reality! :) I'm sure you'll like it! :)

Take care! :)

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Did you find this post helpful? Do you wish to contribute to other projects regarding computer science, electronics, robotics or mechatronics that will be posted in this blog? If you wish to do so, you can donate via paypal using the button below. Thanks! :)

Blogging: Flickr vs Picasa

Hi! If you're a blogger, or intend to become one someday, you will face yourself with the hard task of choosing which image hosting service to use: Flickr or Google's Picasa Web Albums (now also known as Google Photos). I had to go through this myself and as such I'm going to describe my short analysis on both services and why I'm sticking with Google Photos. I'd like to point out that this analysis concerns only the free accounts.

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How to view the processor information in Linux

Hi everyone! This is going to be a really short post but I think that someday it may be useful for you like it is for me. Sometimes friends, family or strangers give me/throw away old/damaged computers (some aren't damaged at all and can be fixed by formatting the hard drive :) ).  Whenever I get my hands in one of these computers I want to find out about the specs of the hardware. In this post I'll show you how to get info about the processor if you have a running computer. Basically, start a console and run:

cat /proc/cpuinfo

and you'll get all the info about the CPU, just like shown in the image below :) .

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CNC Controller Board v2

As I said previously, I have been slowly developing my second CNC Machine, TheMaker2. To control the new CNC machine I developed a new board based on a PIC16LF877A since the L297's that I used on the first CNC controller board that I designed can be quite expensive here in Portugal and I had some PIC16LF877A samples lying around that with a few programming lines could do the same or even more than three L297 stepper motor controllers.

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Once again, the board design can be split in three parts:

1. Isolation - it has Vishay's CNY17-2 optocouplers to isolate the parallel port from the rest of the circuit;
2. Driver - a Microchips' PIC16LF877A drives three stepper motors in unipolar mode (if you prefer bipolar you can change the schematics and boards at your will);
3. Power Interface - a bunch of Vishay's SUP85N03 N channel FETs working as switches controlled by the PIC16LF877A.

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Homemade CNC: TheMaker2

Hi! As I previously said in my first post about my first Homemade CNC: TheMaker1, I was slowly developing a bigger, faster (didn't accomplish this part yet) and more robust CNC. Well, the development phase has finally come to an end and it is finally ready! :D In order to build a more rigid structure I decided not to build it with a moving gantry, but with a moving table on x axis and a fixed structure for y axis, which holds z axis. The build is based on this one.

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One of the main objectives was to make it low cost and believe it or not, with some scavenging involved I managed to build the whole structure with only 84.4€! :D Oh, and this cost still includes some spare materials! :P

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The BiT Bang Theory Blog is 1 Year old

Hi everyone! It has been a long time since I last posted something and some of you probably thought that this blog had been forgotten but it didn't :) I have been working on moving the blog from wordpress to blogspot since it gives me more freedom to make this blog unique. Also, since I was moving the blog I kept some stuff to publish in the new version :) But more on that later. First I'm going to make a balance on this first year of tech/hack blogging :) .

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Adding an external power supply to a cheap USB hub

Hi again! In this post I'm going to show you how to add an external power supply to a cheap USB hub. :)

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I've been running some experiments with two Logitech Quickcam for Notebooks Pro and the Raspberry Pi and unfortunately I haven't been getting any good results. I can't get many fps and some of the captured frames contain corrupted data but I think I may have found out the reason for that. After some reading I verified that the USB ports of the Raspberry Pi can only source 100mA to a device and maybe the cameras are consuming more than that. To bypass that problem I went out to buy a USB hub with external power supply.

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How to locate files in linux

Hi! Have you ever needed to find some files in linux? Here's a quick and easy "How To" on it. To locate files you can use the command "locate" (yes, to locate, use "locate", pretty obvious, huh? :P). If you know the name of the file just launch a terminal and write:

locate "filename" 

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How to resize multiple images at once

Hi! This post is about a common need for everyone. That's highly probable that, at least once, you needed to resize lots of pictures, either to spare some storage space or just because you needed them to have a specific size for some reason. Below you'll find a script to do it with no effort :) It is based on my previous script for Overlaying a logo in multiple images at once. Once again we'll use the "convert" program from the Imagemagick toolkit.

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How to create a video from multiple images

Hi! If you work with computer vision maybe you have had the need to generate a video from a sequence of images, in order to get a dynamic view of your results. I'm going to show you a very easy way to do that with a simple command, using ffmpeg :) .

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Inexpensive CD Wallet Electronics Tool Kit

Hi! Maybe you're an electronics student, maybe you're an electronics hobbyist, maybe you just had the misfortune of being reading this blog and finding this post :P Anyway, you might find it useful. I'm going to describe how to make an inexpensive (20€), small and portable tool kit with the essential tools for some electronics experimenting or some practical lectures at the university's labs.

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First Impressions on the Raspberry Pi

Hi again! A few days ago I made a post about the Raspberry Pi board that I recently got in the mail. I only made a short description of the board since I hadn't test it at the time. I still haven't much to say but I have finally tested it and I'll share my first impressions of the board.

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