Page 60 - Hacking Roomba

Building a chapter

Roomba Serial

Interface Tether

hen attempting to communicate with a new device for the first
time, always go for the simplest, most direct communication in this chapter
Wpath. Eventually the Roomba robotic vacuum will be on a Wi-Fi
net, but you’ll begin with a simple serial cable.
Explore how to
In the later Roomba projects, if nothing seems to work and it’s unclear if design and build
the robot is even alive, revert back to the serial port tether. Verify the basics. electronics
The first troubleshooting question should always be, “Is it plugged in?” In
the case of Roomba, this translates into, “Can I talk to the Roomba?” The
serial tether is the simplest method of verifying computer-to-Roomba con- Read and
nectivity. From a solid foundation of known-good systems, work back up understand
until the problem is found. circuit schematics
for voltage
The serial tether circuit is simple, but this chapter goes into more detail
describing and building it than you might expect. This extra detail is to give regulators,
explanations as to why the parts of the circuit are designed the way they are LEDs, and serial
and to show some of the rules-of-thumb that hackers use every day when transceivers
designing circuits. This chapter is used as an introduction to designing and
building electronics for those who don’t do it regularly. If you’re an experi- Build an RS-232
enced hacker, you can probably just look at the schematic, build it, and skip serial adapter
to the last section.
Send commands
to Roomba
Alternatives

The serial tether presented here is just one possible design. There are several
ways to solve this problem. The particular design is meant to be compatible
with as many computers and embedded systems as possible. Also, it was
designed to use such standard components that hackers are likely to have all
the parts they need in their junk drawers. However, if you don’t have a well-
stocked junk drawer, you want to start playing robot with your Roomba
right now, or you want a slightly more compact tether, there are alternatives.
These alternatives cost more money, but they all function the same with the
software in the rest of the book.