AVR microcontrollers and Arduinos. (by alaric)
I'm a fan of the Atmel AVR microcontroller. The main competitors in its area are the older 8051 and PIC architectures, which have less pleasant instruction sets and are generally harder to program.
Ease of programming is key. Most AVRs can be programmer via a SPI link, which is just four digital I/O pins following a widespread standard that most microcontrollers can drive, and there are widespread interfaces to drive an SPI bus from a PC. It's almost as good as the LPC2000 series 32-bit microcontrollers' asynchronous serial programming interface, which can be driven from an RS-232 port with a little bit of level shifting. I'm also a fan of the LPC2000s, but they fit into a higher-powered niche than the AVRs!
A long time ago I did some AVR development professionally, with a programming board driven from a PC parallel port by some Windows software. I still have the board, and a windows PC with a parallel port and the software installed sitting under a desk, but the "activation energy" of getting the PC powered up and plugged into a keyboard and monitor, and digging out the board, and having to deal with Windows-based development software and all that has stopped me from doing anything with AVRs for a while, given my shortage of time.
However, Sarah has tasked me with developing some electronics for her, as part of a project she's working on. And it looked like the easiest way of doing what's required will be to drop an AVR in.
But rather than dig out the Windows-based dev environment, I've just picked up a USBtiny ISP kit for less money than my original AVR dev system cost. It runs off of a USB port, and supports an entirely open-source AVR toolchain that I can run on my laptop. Inside, it's just an AVR itself, with a USB interface on one end and a SPI interface on the other; everything that I need in one neat little package.
As a plus, it has a cable coming out that I can plug into a header on the board the AVR is part of; my old dev board needed me to pull the chip out of its circuit and put it into the board to program it. Pah!
But while I was there, I also picked up an Arduino Uno. This is a little gadget that has been taking the hobbyist electronics world by storm lately; it's basically an AVR on a board with an inbuilt USB programming interface and a bunch of female headers to make it easy to wire up to various things, and some software to let you program it in C easily with a useful library. There's a wide range of boards that plug directly into the headers to do all sorts of fun stuff, too.
Now, I'm a bit disdainful of the Arduino; given the ability to program bare AVRs directly and to assemble my own circuits on protoboard, I can easily do all sorts of stuff that Arduinos can't, at a fraction of the cost.
However, they're great for beginners, as they are plug and play devices; you can get started without touching a soldering iron or having to work out which pin is which. My disdain is purely personal, I think they're a great thing for the community as a whole 🙂
So why am I getting one, I hear you ask? Well, I have a wife who wants to be able to control LEDs and a six year old daughter who is passionate about building a robot, so I'll be glad to have an easy-to-use module I can just hand them rather than needing to build AVR boards for them all the time; but mainly, I plan to use it as a Bus Pirate clone by putting a FORTH on it along with some words to do things like I2C and SPI...
Electronics | alaric | 
Fri 8th Jun 2012 9:59 am
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