Page 255 - Hacking Roomba

236 Part III — More Complex Interfacing

Parts and Tools

To build the Wi-Fi Roomba adapter, you’ll need the following parts:

Lantronix WiMicro, Mouser part number 515-WM11A0002-01
Mini-DIN 8-pin cable, Jameco part number 10604
7805 +5 VDC voltage regulator, Jameco part number 51262
Two 1µF polarized electrolytic capacitors, Jameco part number 94160PS
Two 8-pin header receptacle, Jameco part number 70754
General-purpose circuit board, Radio Shack part number 276-150

Except for the WiMicro, all the parts you’ve seen before from previous projects, and the circuit
you’ll be constructing is very similar to previous ones, so you’ll need all the same tools.
To aid in setting up, it would be helpful to have a dedicated wireless access point not connected
to your home network. In a pinch you can use your computer in either ad-hoc or Internet shar-
ing mode.

Lantronix WiMicro

Lantronix makes the XPort seen in the previous chapter. The wireless brother of the XPort is
the WiPort. It is a tiny silver box with a pigtail antenna lead coming out of it and a high-density
set of pins on its bottom. Like the XPort, it’s not very hacker-friendly because of its pinout and
3.3V power requirements.
Lantronix also makes the WiMicro (shown in Figure 12-2), which contains a WiPort and
some support circuitry. It is mostly a drop-in upgrade for their Micro (also known as Cobox
Micro) Ethernet board. Like the Micro, it is more hacker-friendly with a standard 0.1˝ spacing
header connector on its underside and is driven by +5 VDC (see Figure 12-3). The pinout
of this header is the same as the Micro and is shown in the diagram on the right side of
Figure 12-4. The left side of Figure 12-4 shows the location of the header on the WiMicro
board when looking at it from the top. Connecting the WiMicro to your circuit is easy: hook
up the +5V and GND for power and TXA and RXA to serial in/out.
The WiMicro board is not cheap. One board costs $165 from Mouser. Like all Lantronix
devices, it can be configured through web-based interface, telnet, or serial line. It has two serial
ports called A and B, 0 and 1, or Channel 1 and Channel 2, depending on the Lantronix docu-
ment you’re reading. This project shows use of the first serial port (also known as A or 0), but
you can use either. In fact if you have some other device (like a microcontroller controlling
other sensors or actuators as described in the upcoming chapters), you can communicate with it
through the second serial port.