4.1 Hardware Overview
In this application, the elements of the LoRa network (i.e. sensor node and gateway) are realized using the existing evaluation boards instead of developing a custom hardware.
The LoRa sensor node is a standalone battery-powered end-device and belongs to Class-A category of end-devices. The sensor node is modeled using the existing XMEGA-A3BU Xplained and RN2483 LoRa Technology Mote evaluation boards.
- Since the XMEGA-A3BU Xplained board comes with the ATxmega256A3BU MCU, the application demonstrates a sensor node with an ATxmega256A3BU MCU. The developers may consider an XMEGA AU MCU with lower memory footprint for their applications depending upon the program and data memory requirements.
As shown in Figure 4-1, the XMEGA-A3BU Xplained and RN2483 LoRa Technology Mote evaluation boards are connected through a UART interface. The 3V battery source on the LoRa mote board powers both the evaluation boards.
The onboard temperature and light sensors of XMEGA-A3BU Xplained are used to monitor the ambient light and temperature. The LCD display on XMEGA-A3BU Xplained provides feedback on connection status, sensors data, and down-link transmission data or acknowledgments. The RTC32 works with battery backup feature. The 3V battery source and external 32 kHz crystal oscillator is to power and enable the clock for the RTC32 module in power down mode.
The RN2483 LoRa transceiver module alone is enabled on the LoRa mote evaluation board. The onboard LCD display, sensors, and PIC MCU are isolated from the sensor node circuitry.
The LoRa gateway core board available with the Microchip LoRa technology evaluation kit is used as a gateway for the LoRa network. The gateway is connected to the TTN server via an Ethernet LAN port. The following subsections give a brief overview of the evaluation boards used to realize a LoRa network.