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PIC Microcontrollers


Technically, a PIC is one of a series of microcontrollers made by Microchip Technology. The name PIC initially meant "Programmable Interface Controller." This latter became "Programmable Intelligent Computer." It is sometimes referred to as a Programmable Integrated Circuit. Essentially, it is a "computer on a chip." PICs have a processor, memory to hold and run a program and input and output pins. Using a PIC may seem daunting for teams but there are several products available to make them easier to use.

This is not an exhaustive list of microcontroller/microcomputer products. It is simply an introduction to three products that seem to be widely used.

It is important to note that under the current Destination Imagination Rules of the Road (2007-2008), PICs (including the Lego Mindstorm) are not included in the definitions of computers and are thus not exempt from cost.

Lego Mindstorm

Lego Mindstorms uses a specialized version of a PIC as its controlling device. Mindstorms is a good way to gain a basic understanding of microcomputers. The Mindstorm sets include various input and output devices with instructions on how to use them. The kits also include projects that users can build that teach how the various devices work. It is programmed with a "drag and drop" interface. The program is created using "blocks" to create a flowchart form using a graphic user interface. The cost of a Mindstorm set would make it very difficult to fit into any DI solution but it is probably the best introduction to microcomputers for very young teams.

Basic Stamp II

Another popular product is the BASIC Stamp Microcomputer by Parallax. It is a step up in difficulty from Lego Mindstorms. The BASIC stamp has a built in BASIC interpreter on board and is programmed in a subset of BASIC (Beginners All Symbolic Instruction Code). The programs are written in text form but BASIC is relatively easy to read and even a person with little or no experience can get a limited understanding of what a program is doing just by reading it. Parallax sells several products including the Basic Stamp I and the Basic Stamp II. The Basic Stamp II is what beginners should start with. They sell several learning kits for the Basic Stamp II that can teach teams how to use and program the Stamp II in a variety of projects.

The Basic Stamp II is not as easy to use as the Mindstorm but it also has more capabilities since the microcontroller is not as insulated from the user.

The popularity of the Basic Stamp also means that there are a multitude of websites where people have posted circuits and programs showing how they have used the Basic Stamp in various projects. After gaining some experience with the Stamp kit projects it would be easy for many teams to adapt the designs and programs they find on the internet to create their own unique solutions. As an example of this: On the Servo Page of this website there is a video of a simple control of a servo using a potentiometer. I know very little about Servos or the Basic Stamp but found an example of creating a controller for a servo on the internet and was able to complete the controller in less than an hour. Cost is still somewhat of an issue for the Basic Stamp since they Basic Stamp II retails in the $40 - $50 range. However, I have watched ebay and seen the Stamp II sell in the $20 range. After a team gains experience they could learn to use the Basic Stamp I which has more limited capabilities but retails for $29.00. I have seen a Basic Stamp 1 sell for as little as $10 on ebay. Add a simple carrier circuit board and you could have a microcomputer for less than $20. All of the manuals for Basic Stamp Educational kits appear to be available for download from the Parallax website. This IMAGE gives you an idea of the size of the Basic Stamp I. The Basic Stamp 1 is the small IC to the right of the quarter. The circuit board is a carrier board for mounting the Basic Stamp 1 and creating small circuits. The Basic Stamp II is larger than the Basic Stamp I but in either case the devices are small.

Parallax sells a product called the Javelin Stamp which is similar to the Basic Stamp but runs a subset of Java. The cost of the Javelin stamp would make them very difficult to include in a DI Solution.

Another product from Parallax is called the "Propeller Chip". The Propeller contains eight thirty-two bit processors on a chip. The Parallax website indicates "The Propeller product line is recommended for those with previous microcontroller experience." However, once a team has mastered microcontrollers it could be worth the time to learn to use and program the Propeller chip because the individual chips sell for around $13. Check the Parallax website for more information.

In England there is a product similar to the Basic Stamp called the PICAXE. The PICAXE comes in several versions, each one successively more powerful (and more expensive) than the next. The PICAXE can be programmed graphically using flowcharts, or programmatically using a BASIC style language. Additional information on the PICAXE can be found at: http://www.rev-ed.co.uk/picaxe.

Arduino

Arduino is another microcontroller product that is available. Arduino is an open-source microcontroller platform. Basically, this means that the product is being developed by the users. Adruino would appeal to those teams who really "get into" microcomputers. Arduino devices are more difficult for beginners to learn to use. Educational material is available but not to the extent of that available for the Basic Stamp. Arduino is programmed in a lower level programming language ("C") than the Basic Stamp.

Information on where to purchase Arduino products can be found at http://www.arduino.cc/en/Main/Buy.

An advantage of the open-source platform is that prices tend to be lower than for a regular commercial product. A disadvantage of open source is that there tend to be "bugs" in the software for programming and using the microcontrollers. The ""bugs" eventually get fixed but not as quickly as with a product that is being developed by one company.