Page 465 - Robot Builder's Bonanza

434 AN OVERVIEW OF ROBOT “BRAINS”

communications. You’ll be able to send and receive simultaneously. If the data speed is fast
enough, you can readily command the robot to move around a room and have it beam back
pictures via its video camera.
Data speeds for wireless communications depend on the distance between sender and
receiver, and on the technology. Wi- Fi is faster than Bluetooth, which is (usually) faster than
Zigbee. At longer distances, data speeds are reduced to avoid errors. Most RF data communi-
cations systems can be used 50 to 100 feet from source to target. For infrared, the distance
is much less.

SMARTPHONES, TABLETS, AND PDAS
Rounding out the discussion of brains for your robot are smartphones, computer tablets, and
personal data assistants (PDAs). To be useful as a robot brain, the device:

• Should be user programmable. A PDA or smartphone that won’t let you add your own
programs is useless as a robot controller.
• Provides some kind of communications link between itself and the robot electronics. On
many devices this is through Bluetooth, but on others you need to use USB, if available.

Microsoft, Google, and several others tout smartphones that allow you to write and upload
your own programs. Example: Microsoft smartphones run Windows Mobile, a version of Win-
dows tailor- made for use on small devices. You can write programs using Microsoft Visual Basic
.Net or C#.Net (both free from Microsoft) for use on the phone. Phones that use the open- source
Android operating system developed by Google offer similar programming features.
The disadvantage of these devices is the limitations inherent in their design as products that
are made for something other than robot control. Their programming tools are not designed
to control real- world devices, so developing a robot application tends to involve a lot of com-
promises.

Of Inputs and Outputs

The architecture of robots requires inputs— things like sensors and bumper switches. And
then there’s outputs, such as motor control, light, and sound. The basic input and output of a
computer or microcontroller is a two- state voltage level (that is, off and on), which usually
equates to 0 and 5 volts. For example, to place an output of a computer or microcontroller to
HIGH, the voltage on that output is placed, under software control, to 5 volts.

G In programming, LOW is equivalent to off, or binary 0. HIGH is equivalent to on, or binary 1.
The LOWs and HIGHs are bits. Read more about basic programming for robotics in Chapter
36, “Programming Concepts: The Fundamentals.”
Inputs and outputs are colloquially referred to as I/O. In addition to standard LOW/HIGH
inputs and outputs, there are several other forms of I/O found on single- board computers and
microcontrollers. The more common are listed in the following sections, organized by type.
Several of these are discussed in more detail in Chapter 40, “Interfacing Hardware with Your
Microcontroller or Computer.”

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