Leandro A. F. Pereira

It’s been a while since I’ve started this blog, and I believe it’s time to start over. That’s why I’m moving it to tia.mat.br, using a new content management system (that generates static files, to avoid having to upgrade WordPress everytime). I also intend to blog frequently, and only in English. See you there!

Last week I was in Belgium, attending the Free and Open Source Developers European Meeting — FOSDEM, for short. This conference is held every year and gathers people from all around the globe to discuss and publish FOSS-related matters. Belgian beer, waffles, dutchfrench fries, and sub-zero temperatures were also in the agenda.

Enlightenment Project group photo. Picture by Stefan Schmidt. Guess who I am? (Click to see a larger version.)

I talked briefly about testing in WebKit EFL, after the required tools have been implemented last year, and how it affected the quality of the port. Although I could broadcast what I was there for, the need to improve my public-speaking skills (specially in a foreign language) surely exists; I guess that the only way to improve this is practice. One could say I traveled a long distance just to talk fifteen minutes about software testing, but such places have a lot more to offer.

I’ve met a lot of people this time around (I’ve attended the same conference last year as well): people from the WebKit project (from Qt and GTK+ ports mostly — unfortunately meeting the Mac/Chromium guys in such events is a little bit more complicated), the EFL project, and watched some lectures on interesting subjects, such as domain-specific-languages&LLVM, text input in mobile devices (and how difficult it is), multi-path TCP (very interesting, by the way!), and even saw the old manRasterman talking about Duke Nukem ForeverEFL to a large audience. Unfortunately, I wasn’t able to meet people I’d like to meet (the CMake guys, which I talked briefly while working on the WebKit-EFL build system), due to overlapping schedules. Oh, well.

Devices with Tizen were also there if you knew where to look and I was able to play around with them. Despite it still being a little bit rough in the edges (pun intended), I was very impressed by the overall smoothness. Granted that the hardware isn’t too shabby, but it was as snappy as an user interface should be. Can’t wait to get my hands on a Tizen device I can call my own.

I’ve also had the opportunity to drink more Club-Mate in the Brussels Hackerspace (in a new place since last year). Unfortunately my hackerspace passport arrived in the mail a couple days after I left for Europe, so I couldn’t get it properly stamped.

All in all, it was a great experience. I sure hope I’ll be able to attend this conference next year. And last, but certainly not least, I’d like to thank my employer, ProFUSION Embedded Systems, for sponsoring my trip.

Na última quarta feira ocorreu a segunda noite de introdução ao Arduino no LHC. Além de pizza grátis, quem participou teve a oportunidade de aprender sobre o funcionamento básico do Arduino: as funções setup() e loop(), I/O analógico e digital, delays, e até mesmo implementação de um protocolo serial via software.

As brincadeiras com I/O giraram ao redor de oito LEDs conectados em uma protoboard e aos pinos de I/O 0-7 de um Seeeduino. Um trimpot atuando como divisor de tensão foi usado na entrada analógica 0 para controlar a velocidade de marcha dos LEDs ou escolher qual LED acender, de acordo com o valor lido pelo conversor analógico-digital.

A implementação do protocolo serial via software, usando técnica de bitbanging, foi feita para interfacear um módulo de display da OSRAM, o SCDQ5541.

No próximo encontro, devemos brincar com registradores de deslocamento ou charlieplexing, para acender uma quantidade maior de LEDs, afim de construir um cubo.

No dia 20 de Outubro, ocorreu a primeira noite do radioamadorismo no Laboratório Hacker de Campinas (LHC). A idéia dessas noites é reunir pessoas interessadas em aprender sobre o assunto e fazer experimentos com rádio.

O Juba trouxe (e deixou no LHC) um transceptor de rádio amador, com antena dipolo e caixa acústica. Conseguimos captar, mesmo com uma instalação precária da antena nas grades da janela, sinais de outros países (ou pelo menos em outros idiomas, como Chinês, Russo e Espanhol), e algumas transmissões nacionais também.

Além disso, brincamos com uma USRP, que é basicamente uma interface para receber o sinal analógico do rádio e transmití-lo pela USB para processamento em software pelo GNU Radio. Rodamos alguns dos exemplos do GNU Radio e conseguimos sintonizar rádios FM comerciais e ver o sinal de walkie talkies GMRS (deu pra ver a portadora do sinal e as distorções que acontecem depois da demodulação, mas não conseguimos de fato ouvir a voz).

No próximo encontro, devemos fazer uma instalação melhor da antena e começar a preparar o material para conseguir a licença de estação para a Anatel. O Juba já tem licença de radioamador e eu pretendo conseguir uma também.