Hardware Reference
In-Depth Information
Other Microcontrollers
Though the examples in this topic focus on Arduino,
there are many other microcontroller platforms that
you can use to do the same work. Despite differences
among the platforms, there are some principles that
apply to them all. They're basically small computers.
They communicate with the world by turning on or off
the voltage on their output pins, or reading voltage
changes on their input pins. Most microcontrollers can
read variable voltage changes on a subset of their I/O
pins. All microcontrollers can communicate with other
computers using one or more forms of digital communi-
cation. Listed below are a few other microcontrollers on
the market today.
of the Basic Stamps and PICAXEs. The Basic Stamp,
PICAXE, Wiring, and Arduino environments are essen-
tially wrappers around these controllers, making them
easier to work with. To use PICs or AVRs on their own,
you need a hardware programmer that connects to your
computer, and you need to install a programming envi-
ronment and a compiler.
Though the microcontrollers themselves are cheap
(between $1 and $10 apiece), getting all the tools set
up for yourself can cost you some money. There's also
a pretty significant time investment in getting set up,
as the tools for programming these controllers from
scratch assume a level of technical knowledge—both
in software and hardware—that's higher than the other
tools listed here.
8-bit controllers
The Atmel microcontrollers that are at the heart of both
Arduino and Wiring are 8-bit controllers, meaning that
they can process data and instructions in 8-bit chunks.
8-bit controllers are cheap and ubiquitous, and they can
sense and control things in the physical world very effec-
tively. They can sense simple physical characteristics at
a resolution and speed that exceeds our senses. They
show up in nearly every electronic device in your life,
from your clock radio to your car to your refrigerator.
32-bit controllers
Your personal computer is likely using a 64-bit processor,
and your mobile phone is likely using a 32-bit processor.
These processors are capable of more complex tasks,
such as multitasking and media control and playback.
Initially, 32-bit processors were neither affordable nor
easy to program, but that has been changing rapidly in
the last couple of years, and there are now several 32-bit
microcontroller platforms on the market. Texas Instru-
ments' BeagleBoard (
http://beagleboard.org
) is a 32-bit
processor board with almost everything you need to
make a basic personal computer: HDMI video out, USB,
SD card and connections for mass storage devices, and
more. It can run a minimal version of the Linux operating
system. Netduino (
www.netduino.com
) is a 32-bit
processor designed to take Arduino shields, but it's pro-
grammed using an open source version of Microsoft's
.NET programming framework. LeafLabs' Maple (
http://
leaflabs.com
) is another 32-bit processor that uses the
same footprint as the Arduino Uno, and is programmed
in C/C++ like the Arduino and Wiring boards. In addition
to these, there are several others coming on the market
in the near future.
There are many other 8-bit controllers that are great for
building physical devices. Parallax (
www.parallax.com
)
Basic Stamp and Basic Stamp 2 (BS-2) are probably
the most common microcontrollers in the hobbyist
market. They are easy to use and include the same basic
functions as Wiring and Arduino. However, the language
they're programmed in, PBASIC, lacks the ability to pass
parameters to functions, which makes programming
many of the examples shown in this topic more difficult.
Revolution Education's PICAXE environment (
www.
rev-ed.co.uk
) is very similar to the PBASIC of the Basic
Stamp, but it's a less expensive way to get started than
the Basic Stamp. Both the PICAXE and the Stamp are
capable of doing the things shown in this topic, but their
limited programming language makes the doing a bit
more tedious.
PIC and AVR
Microchip's PIC (
www.microchip.com
) and Atmel's AVR
are excellent microcontrollers. You'll find the AVRs at the
heart of Arduino and Wiring, and the PICs at the heart
The increasing ease-of-use of 32-bit processors is
bringing exciting changes for makers of physical inter-
faces, though not necessarily in basic input and output.
8-bit controllers can already sense simple physical
