Making Things Talk

356 MAKING THINGS TALK

Asterisk

Asterisk is an open source private branch telephone

exchange (PBX). It allows you to manage a phone

exchange over an IP network. It can make and take phone

calls, save messages, play prerecorded messages to

people who call in, and offers most of the usual features

a phone account does, like caller ID, call waiting, call

blocking, and so forth. You can also make connections

between the phone and the Internet. For example, you can

allow users to control the output of a PHP script using

their touchtone keypad. It’s not a large step from there

to having a mobile phone keypad controlling a physical

object through a Lantronix device, XBee radio, or any of

the other tools you’ve seen here. It runs on a Unix or Linux

server. Asterisk isn’t easy for the beginner, but it’s manage-

able by anyone comfortable with server-side programming

like the PHP you’ve seen here. For more details on Asterisk,

see www.asterisk.org.

The mobile phone development landscape is changing

rapidly at the moment, and by the time you’re reading this,

there are likely many more tools for developing on phones,

and for using phones as a user interface to networks in

nontraditional ways. If you’ve enjoyed making embedded

systems talk to each other, then by all means, jump into

mobile phone programming as well.

X

Other Microcontrollers

Though the examples in this book have all been done using Arduino and Wiring, there

are many other microcontroller platforms that you can use to do the same work. This

section is an introduction to a few others on the market, and what they’re good for.

Some of these are standalone controllers that you program yourself, as you’ve done

with the controllers in this book. Others are designed to be connected to a personal

computer at all times. You don’t have to program these, you just configure them via

serial or Ethernet, then read from their inputs and write to their outputs from your

desktop-based development environment.

Basic Stamp

Parallax (www.parallax.com) Basic Stamp and Basic

Stamp 2 (BS-2) are probably the most common microcon-

trollers in the hobbyist market. Programmed in PBASIC,

they are easy to use, and include the same basic functions

as Wiring and Arduino: digital in and out, serial in and out,

PWM out, and a form of analog in. Their analog in is slower

than an analog-to-digital converter, however. In addition,

PBASIC lacks the ability to pass parameters to functions,

which makes programming many of the examples shown

in this book more difficult. It’s possible to do everything

you’ve seen here on a Basic Stamp, however. And there

are more code samples available on the Net for the BS-2

than for just about any other controller.

BX-24

NetMedia’s BX-24 controller (www.basicx.com) affords

everything that Wiring and Arduino do; in fact, it’s even

based on the same microcontroller family that those two

are (the Atmel AVR controllers). It’s programmed in a

variant of Visual BASIC (BasicX), and even includes limited

support for multitasking. The programming environment

for it is available only on Windows, however. Of the various

Basic Stamp–like modules on the market, it’s arguably the

best, especially for tasks like the ones found in this book. It’s

a decent alternative for networked objects for beginners.

The BX-24 and the Basic Stamp both cost around $50

apiece, and by the time you’ve bought the starter kit,

around $100.

Making_Things_Talk.indb 356 11/13/09 4:57 PM