Introduction to motes



Motes are sensor nodes manufactured by CrossBow. A motes has a sensor unit, a power unit, a transceiver unit, a ADC unit and a processor. We have two kinds of motes These two contain a processor and a transceiver unit and they have connectors for attaching sensor boards to them. A sensor board consists of a set of sensing units. We have MTS300CA sensor board. This can be interfaced with MICA2 mote. The sensing units in MTS300CA are The motes can be programmed by attaching them to the Mote Interface Board (MIB500CA). The MIB can be interfaced with the PC by connecting it to the parallel port. The mote has an on board flash that can be programmed. The mote that is to be programmed is connected to the 51 pin male connector on the board. Motes run a multithreaded operating system called TinyOS. TinyOS is based on component model. Each component declares the commands it uses and the events it will signal. A simple FIFO scheduler will be part of each program uploaded onto the mote. The program will consists of codes for components that will be used. The components communicate with each other by passing commands. Events are usually initiated by hardware devices. Based on the event, the component related to that event will generate one or more commands to other components. TinyOS system, libraries and applications are written in NesC language. NesC has a C like syntax. The machine to which the MIB is connected will contain the TinyOS code (i.e.) the code for the components. We write our code by using the component code that is already present in TinyOS. After writing to compile the program we use ncc compiler. The output by default is called main.exe. Then avr-objcopy converts the exe file produced by ncc into a text format that can be used for programming the mote's flash. The sensor board collects data and sends it to the mote which can either store the data or transmit the data to the base station. A base station is nothing but a mote attached to a Mote Interface Board(MIB) that is interfaced to a PC via the parallel port.

The programming environment for motes is currently setup in lab BY 517. It is setup on the second machine from the entrance. To program first run cygwin batch file located on the desktop. Cygwin is a linux like environment for windows machines. Attach the mote to a MIB then attach the MIB to the PC via the parallel port. Change directory in the cygwin window to /cygdrive/c/tinyos-1.x/. This is the directory that contains the source files for tinyos. This directory also contains sample applications that can be run on motes (apps directory). Change directory to apps. Apps directory contains a set of directories each of which contain an application. To compile an application type "make mica2". If it is successful it will output the amount of RAM and ROM space the program will require. The output of the make command will be main.srec. Now this can be used for programming the flash memory. The make file has an install option that takes care of uploading the program onto the flash. The install option uses a program called "uisp" to upload the program onto the flash. The TinyOS directory also contains tiny os tutorial. It also contains manuals for motes, sensor boards and tiny os.

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