Teensy 3.0 announced with Cortex M4

Here’s a new creation from Paul Stoffregen, creator of the Teensy board. This third evolution of the Teensy series brings an ARM Cortex M4 of the Kinetis family for more processing power and connection capabilities, while still programmable with the Arduino language and software.

What is interesting here (among the other set of features listed below), is the presence of SIMD instructions (used for DSP processing), and an I2S interface to connect to a high quality audio DAC. Some higher variants of this chip include an FPU, but this specific one lacks it.

Another nice feature is the high number of timers and their independance from PWM channels, which allow internal event systems without compromising on output capabilities.

Technical Specifications:

  • 32 bit ARM Cortex-M4 48 MHz CPU (M4 = DSP extensions)
  • 128K Flash Memory, 16K RAM, 2K EEPROM
  • 14* High Resolution Analog Inputs (13 bits usable, 16 bit hardware)
  • 34* Digital I/O Pins (10 shared with analog)
  • 10 PWM outputs
  • 8 Timers for intervals/delays, separate from PWM
  • USB with dedicated DMA memory transfers
  • 3 UARTs (serial ports)
  • SPI, I2C, I2S, IR modulator
  • I2S (for high quality audio interface)
  • Real Time Clock (with user-added 32.768 crystal and battery)
  • 4 general purpose DMA channels (separate from USB)
  • Touch Sensor Inputs

Nice job, Paul!

Fritzing review

Fritzing is an open-source initiative to support designers, artists, researchers and hobbyists to work creatively with interactive electronics. We are creating a software and website in the spirit of Processing and Arduino, developing a tool that allows users to document their prototypes, sharethem with others, teach electronics in a classroom, and to create a pcb layout for professional manufacturing.

In a nutshell, this software acts like a virtual breadboard for tinkering with electronic kits. You can even program an Arduino from within Fritzing without leaving the app, and you can add your own parts (Sparkfun’s comes with the software natively, see also Adafruit’s part repository).

Raspberry Pi and 16×2 LCD

Got a RasPi and an LCD screen? You can hook it up to display some info (like the IP address here, very handy when using DHCP and carrying your Pi around).
The LCD does not need to be a 3.3V model, mine is a 5V and works like a charm.

Once attached to the GPIO, you can use a python program to send some text to write.

Read more on Adafruit – Drive a 16×2 LCD directly with a Raspberry Pi

The examples show a clock and the IP address but it might be better to display events that only occur from time to time (the clock script runs continuously).

Playing with QR code

You can insert a logo in the middle of a QR code, as long as some parts of it remain untouched.

I followed the following tutorial:

Basically, as long as your logo does not overlay with the code’s required pixels, you’ll be fine. Here’s a “keepout map” explaining where these pixels are. 

Git on Pi

Git is a great tool for version control. I used SVN in the past but Git is simply more powerful, although a bit harder to understand for the newcomers.

I use GitHub for most of my open-source projects, but sometimes I would like to set up some private Git repositories for non-open source stuff (like private data, files and backups). That’s a job for the Raspberry Pi !

Back in the days of SVN, administrating repositories was a pain in the ***, and it could have been the same with git if it wasn’t for a nifty little tool: gitolite.

Gitolite helps you create repositories, users, manage access, restrictions etc.. And all of this is done.. by using git itself. The configuration file (containing repositories description) is located in an “admin” repository, along with the public keys associated with users allowed to access these repositories.

This way, to add users, you only add their public keys, and edit the config file to choose which repository they’re allowed to access. To create a repository, simply add the name and people granted access to the conf file, and commit/push. It’s that simple.

You can find the instructions on how to setup your own private Git repositories at the Gitolite Readme page, on GitHub.

RSS Feeds

If you can read this message from your favourite RSS feed reader, then it means that the redirection is working!

Otherwise, if you don’t want to keep following the now-deprecated Blogger account, point your feed reader to the following address:


Why would you want to do that? Because:

  • The old blog will not exist forever
  • Better drinking at the source
  • You’d get a nice FSE icon instead of the Blogger icon, if your reader supports icons (okay, not the best argument, but still..)

WordPress migration

As you might have noticed, the blog has moved from Google’s Blogger to a WordPress, on a hosted domain.

I will no longer post on Blogger, apart from redirections to this address, and I will investigate on how to redirect the RSS feed to avoid re-subscribing.

Somehow, the Raspberry Pi could have been a good candidate for hosting WordPress, but I tend to move it from time to time, and I would have needed a domain anyway.

So long, and thanks for all the fish!

Raspberry Pi

I recently acquired this little jewel, a 700MHz ARM11 computer with full HD decoding capabilities and a few other fun specs, all that for 35$!!

Carrying it around in its antistatic bag & cardboard was not very convenient though (not to mention it’s also damn ugly). So I went to the LOG, Grenoble’s hackerspace, and cut an acrylic enclosure with the laser cutter (not without a few difficulties though).

Please specify a Flickr ID for this gallery

Moving to GitHub

I moved the MIDI Library, the MCO firwmare and a few other projects to GitHub.

However, SourceForge was great for storing archives of built products, so I guess I’ll keep GitHub for development and SourceForge for deployment..

Anyhow, I’m leaving SVN after a few years of service. So long, and thanks for all the fish!