How It Works Together - Utah-WiESEL/wren_wsn GitHub Wiki

Several components including the WREN mote, the base station, and the software, work together to bring this system to life.

The WREN mote is used to gather proximity sensor data. It uses RSSI to determine its distance from close by motes based on signal strength and unique mote IDs. The contact data is stored on board until it is collected and downloaded, or it can be analyzed during deployments.

The base station is used for charging, programming, and downloading. The PCBs route 5V and 3.3V power, unique addressing, and the I2C data and clock lines to 100 motes. The addressing uses a large voltage divider for debugging purposes. Charging 100 motes only takes about 2 hours, while the PCBs are able to sustain 10-12 Amps of current. Multiple base stations are can be stacked on top of each other to minimize space and each weighs less than 10 lbs so transportation is relatively easy.

The software component consists of the bootstrap loader (BSL) and user applications. The BSL allows the motes to be programming in mass and hence allows a more scalable system. The BSL is stored in a special section of memory that will be protected and not get erased in standard user programming. While programming the test application, we will override the stock UART BSL with our custom I2C BSL. We chose to work with TinyOS, a more popular embedded operating system, for the WREN. To get started, head over to our repo (tinyos-prod). We have several test applications as examples.