RAREblog

One project I'm hoping to complete in the next day or so is an I2C-based Text LCD for use with the Raspberry Pi. Why bother? After all, the Pi has an HDMI output, and it's easy to connect the Pi via Ethernet or wireless. The problem is that there are situations where you really need a stand-alone display. Stand-alone Pi Projects If you're building a battery-powered  stand alone project you may need an output mechanism that's a bit more informative that a few flashing LEDs,  your power budget may not run to WiFi, and you may want to use what you're making in an environment where a network-based solution is not practical. Another application: running a physical computing course It may be hard to connect to the Pi because you don't know its IP address. Earlier this year I helped to run a couple of workshops covering physical computing on the Pi. Practical considerations meant that we couldn't use monitors for each Pi, and we had to connect to the lo...

The Arduino Yún has been running for a couple of days now. Nothing earth-shattering about that, you might think:  one of my Linux boxes got rebooted  just four times in a decade, twice for house moves, once for a power cut, and once for a kernel upgrade. However,  my Arduino Ethernet board crashes repeatedly after a few hours of air-time. I don't know whether that is due to software problems with the Ethernet stack or a hardware issue, but the Yún seems much more reliable.

A few days ago I started exploring the teensy 3.0 . I'm keen to see if we should consider using the teensy for C3Pi , so I want to get more familiar with the teensy hardware and the development environment. When you install teensy's extensions to the Arduino IDE you are given a chance to install a number of additional libraries that have been tested on the teensy family. One of them - LiquidCrystalFast - caught my eye and I decided to explore it in more detail. The LiquidCrystalFast library LiquidCrystalFast is yet another library for driving text LCDs based on the ubiquitous Hitachi HD44780. I love these displays, and so do many hobbyists; a old post about an  Arduino DVM with LCD display  is one of the most visited pages on this blog. The standard Arduino LiquidCrystal library works pretty well, but suffers from two minor issues. The first is that it doesn't work as it should for 4-row 16-column displays. (It's fine for 2 row displays and for the 4-row 20...

The Arduino Yún is the latest addition to the Arduino range, and it looks very exciting. In this post I'm assuming that you are familiar with the Arduino and with Linux; I may write a beginner's introduction later. The Yún combines the features of a traditional Arduino with a tightly-coupled Linux System-on-a-chip (SoC). The two are seamlessly connected via SPI using a Bridge class on the Arduino and some Python code on the Soc. Easy internet connectivity The Yún's Linux SoC makes it easy to integrate physical computing projects with the Internet. Previously you'd have needed an Ethernet shield or an Ethernet Arduino, using a fairly limited API which was not  always reliable. The Yún gives you many different ways to connect you applications to the internet. Some are useful but very simple; some will take longer to master but look extremely flexible. Shield Compatibility The Yún follows the form factor of its predecessors, so you can use it with many e...

I've just been experimenting with the Teensy 3.0, and it's fantastic. The teensy 3.0 is the latest member of Paul Stoffregen's teensy family. The teensy boards are USB-based micro-controller development environments, like the Arduino but teensy :) Three reasons why I like teensy 3.0 ARM Hardware Arduino Software It's breadboard-friendly ARM Hardware with lots of extra functionality Early versions of the teensy used Atmel AVR chips, like the Arduino, but the teensy 3.0 uses an ARM processor. The  teensy 3.0's CPU is a 32-bit MK20DX128 Cortex-M4 from Freescale. You can run it at up to 96 MHz. That's six times faster than the clock on a typical Arduino, and the speed is matched by plenty of memory for program and data. There's space for 128K bytes of program in flash and 16K bytes of data in RAM. As an added bonus, teensy 3.0 has plenty of pins, both general-purpose and specialised: 34 general-purpose GPIO pins, of which 12 can be used as a...