This chapter describes some salient hardware features of Cricket, the command interface to configure and read various parameters, and discusses troubleshooting and deployment issues.
The Cricket beacon and listener hardware are identical; they just run different software. In fact, there is only one embedded software image, and a runtime configuration switch (described below) determines whether a given unit is a beacon or a listener. By default, each Cricket node is configured to run as a listener. The Cricket embedded software runs in the TinyOS environment .
At least two Crickets are needed to operate the system, at least one beacon and at least one listener. In the current version of Cricket, the listener is usually attached to a host using a serial cable.2.1
The host device (to which the listener is attached) must run software to process the data obtained from the listener. One way to process this data on Linux computers (including handhelds) is to use cricketd (Section 2.2.1), which processes information obtained over the serial interface to obtain various location properties. In particular, cricketd runs on Familiar Linux  (on iPAQ handheld computers), as well as on standard laptop/desktop versions of Linux and Windows (under Cygwin ). We do not currently support cricketd on handhelds running Windows Pocket PC.