Sensor Node
The sensor node integrates sensors, power management, and wireless communication. The sensor nodes itself is modular and consists of one main module (MM) and one sensor module (SM). The two PCBs and the battery are protected by a 3D printed housing, consisting of two parts that latch together.
The two components can be exchanged independently and are connected by the power bus and a serial communication bus.
The sensor module has a microcontroller, which interfaces the onboard sensors. The sensor data is transferred in a standardized format via the serial communication bus to the main module. The main module receives the readings from the sensor board, saves them with a timestamp from the real-time clock (RTC) to the SD-card and sends the data via ZigBee to the gateway.
In the current setting, we are using XBee S2c (XB24CZ7WIT-004). We use the firmware for the product family XB24C with the function set ZIGBEE TH Reg. The firmware version is 405E. We use the default settings. Exceptions are listed below:
| Parameter | Value | Comment |
|---|---|---|
| ID | xxx | PAN ID, can be set to anything, but all nodes in the same network must have the same PAN ID |
| AP | 2 | API mode with escaping |
| SM | 1 | Allows sleep mode to be controlled through sleep pin |
The configuration profiles are also available as files. All XBees corresponding to one coordinator needs to be set to the same PAN ID as the coordinator.