Page 260 - Hacking Roomba

Chapter 12 — Going Wireless with Wi-Fi 241

This combination is easy to get going and works okay. The combined cost is about $120 ($70
for WL-300g, $30 for SitePlayer, $20 for miscellaneous parts), which makes it a little cheaper
than the WiMicro.
The biggest downside is the power consumption. The WL-330g consumes approximately 400
mA by itself. Add in the 150 mA drawn by SitePlayer, and that makes for 550 mA total. The
WiMicro draws around 320 mA when used with Roomba. The difference could mean an extra
hour of run time. You may save some money by using a wireless bridge, but you give up some-
thing else.
Thus reuse of SitePlayer is possible with a wireless bridge, and if you already have one around
the house, try it out. The WiMicro is a nice integrated alternative and the rest of the chapter
will focus on it.

Building the Roomba Wi-Fi Adapter

Due to the WiMicro board, building a Wi-Fi adapter for Roomba is easy. The only additional
part needed beyond the connectors is a 7805 +5V voltage regulator. Figure 12-8 shows the
schematic for the Wi-Fi adapter carrier board that the WiMicro will plug into. All the compo-
nents are familiar and the construction is similar to other carrier boards you’ve created like the
ones for the Bluetooth or Ethernet adapters.

VCC
GND 2 1 5Vin
TXA 4 3 RXA
GND 6 5
8 7
10 9
12 11
WIMICRO

8 mini-din 8pin
GND 7
6
TXD 5
4
RXD 3
2
+16VDC 1
X1
VCC
IN OUT
C1 GND C2
U1
1µF 7805 1µF

GND
FIGURE 12-8: Schematic for WiMicro Roomba carrier board