Page 372 - Hacking Roomba

Chapter 15 — RoombaCam: Adding Eyes to Roomba 353

Listing 15-6 Continued

usbserial
pl2303
videodev
spca5xx_lite
scsi_mod
sd_mod
sg
usb-storage
fat
vfat

Make sure you save any programs you want saved to /usr/bin and not in /tmp. Otherwise,
they’ll disappear on reboot, since /tmp is a RAM disk. This includes roombacmd, camstart,
stty, and any other scripts or commands you want.
The web and CGI files you create live in /www, which is already flash, so you won’t have to
worry about them disappearing.

Building a USB Serial Tether from a Phone Sync Cable

Using the RS-232 serial tether from Chapter 3 with a generic USB-to-serial adapter works
but is very ungainly. The tether’s long cable is hard to manage when the controlling com-
puter is right on top of the Roomba. Building a tether with a shorter cable is definitely pos-
sible, but a really small solution is to use a USB data cable originally meant to sync mobile
phones. Some mobile phones have logic-level serial ports on them instead of USB inter-
faces, and the sync cables contain small USB-to-serial adapters. These cables are available
for about $20 from various places, including Radio Shack. Since this is a Roomba USB
dongle, it’s called the Roombongle.
Things you’ll need to build the Roombongle:

■ USB data cable for Nokia phones (AKA FutureDial Cable 22), Radio Shack part number
17-762
■ Mini-DIN 8-pin cable, Jameco part number 10604

The construction is really straightforward:
1. Acquire the right USB sync cable. Figure 15-11 shows the packaging for the sync cable
used here, and Figure 15-12 shows what the cable looks like. It’s very important to get
Cable 22, which has the bulge in the middle, and not one of the other cables. Other
cables can be used, but you’ll have to figure out the pinouts.
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