Tuesday, October 16, 2012

Choosing Your Microcontroller (Part 2)

Last time, we talked about two sets of microcontrollers, the Arduino Family, and the .net framework family. Today, let's talk about some more.

     PIC microcontrollers are found quite commonly in end user products. They are also used quite frequently in college level electrical engineering courses. These little devices aren't frequently packaged with a board, so using these chips requires some knowledge of being able to build, program, and test circuits. There are, however, a large variety of chips to choose from, with various sizes and functions to suit any need.
     The community around PIC's is fairly great, not necessarily for the reason one would think. The programming environment for PIC's is your basic C language  However, PIC's have been known for what a pain their coding can actually be. Many very simple things that are done with other devices, are quite complicated to achieve in PIC code. These devices are not well suited to the novice programmer or engineer, so beware.

     MSP microcontrollers are extremely power efficient devices by Texas Instruments. These devices aren't as well known, I've found, as the other controllers I've mentioned. They're quite application specific, if you're looking to build your device using as little power as possible. Still, they're great little devices that offer a lot of potential, even if you're not looking to stretch that battery as far as possible. There are a few platform options you have for MSP's. One of which is the Launch Pad, the cheapest microcontroller test board I have ever found. Another such platform is an MSP based watch, the eZ430 Chronos, which includes a 3-axis accelerometer, barometer, and wireless transceivers, as well as being a watch. Most though, like PIC's, are just single chips with varying numbers of pins and functionality.
     Also like the PIC's, these are programmed in C, but can also be programmed in assembly. These can also be quite difficult to utilize some of the functionality at times, but I maintain they're still easier to use than PIC's. The community around MSP's tends to be a little more professional, as these are used more in measurement and extreme longevity projects. Again, not the sort of device the beginning programmer should necessarily be getting into.

     Basic Stamps, by Parallax, have been in the microcontroller game longer than any other I have mentioned. They're one of the first microcontrollers I was exposed to in high school. They have what is probably the largest community of people working and willing to help others on their projects. The company behind these boards, parallax, also develops large amount of externals like servos, sensors and even some Arduino-like shields. The downside to these boards are that they can be quite expensive for not all that much board. The basic "stamp" is a tiny microcontroller, that doesn't include a breadboard or a programmer, is $30.
     The upside to these boards are that they're extremely easy to get into. The getting started kits that they sell include all sorts of tiny bits, IC's, servos, and LED's with a very well written guide explaining all the steps and why everything works. The boards themselves are programmed in a variant of BASIC, which makes following code fairly...basic. If you're looking to get started with microcontrollers, and you have some extra money around, and you don't want an Arduino, then I recommend the BASIC stamp. But splurge and get the "Getting Started" kit.

     The last microcontroller I'm going to talk about is another one from Parallax, the Propeller chip. These are probably some of the most powerful microcontrollers you can buy, offering 8 cores of processing power each at 20 million instructions per second (MIPS). These are definitely for the more advanced hobbyist requiring more knowledge of wiring and programming than the novice. There are a huge number of peripherals to cater to the processor's capabilities including the ability to: generate video signals, interpret device signals such as mouses and keyboards, and easy interface with other devices.
     When it comes to programming these chips, you've got some choices. There is the "Spin Language" aimed more at beginners to the chip, but there is also the capability to program the devices in assembly. Like the BASIC Stamp, there are also such kits that display the various abilities of the chip, so if you're interested in this area, I'd recommend getting on of those. There are such kits that allow you to build basic computers and game consoles. It's the processor behind the YBox, that wonderful little device. So, the Propeller chip is something a little more experienced programmers and hobbyists would enjoy, with its extra power and capabilities.

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