Introduction

“When we talk about the Internet of Things, it’s all about embedding intelligence, so things become smarter and do more than they were proposed to do.” – Nicholas Negroponte

Internet of Things (IoT) has become very popular in today’s embedded world. The Internet of Things is a confluence of powerful and cost-effective microcontrollers, efficient wireless protocols, and enriched sensors. The IoT network comprises embedded technology to sense and communicate with their internal states or the external cloud environment.

The IoT applications demand lower power consumption, secure communication, and extended wireless communication range of connected devices. This enables the IoT systems to cover a wider area while being very power efficient, which in turn helps to achieve longer battery life.

The AVR® XMEGA® AU family of MCUs are peripheral rich, high performance, and low-power 8-bit microcontroller devices. The picoPower® technology and hardware crypto module of XMEGA AU MCUs enable the systems to achieve low-power consumption, encrypted communication, and secure data storage, which is crucial for several IoT applications.

The LoRa® technology is a Low Power Wide Area Network (LPWAN), with key characteristics like wider coverage, lower bandwidth, small packet, and application layer data sizes and long battery life operation. The LoRaWAN network protocol targets key requirements of IoT such as secure bi-directional communication, mobility and localization services.

The combination of the Microchip AVR XMEGA AU family of MCU devices and LoRa wireless transceiver modules offers key features such as low data rate, longer communication range, low power consumption, and a secure and efficient network which are ideal for IoT applications.

This application note discusses the smart IoT wireless sensor node realized using XMEGA AU MCU and LoRa wireless technology.

The application note covers the most vital features of the AVR XMEGA AU product family of MCUs for IoT applications and an overview of the LoRaWAN communication protocol. The supplemented IoT wireless sensor node firmware is developed using the Microchip ATxmega256A3BU MCU. The firmware offers a LoRa sensor node with various methods to join (i.e. ABP, OTAA) to a LoRa network. After successful connection to the LoRa network, the firmware periodically monitors sensors and transmit the acquired data to a cloud-based network server through a gateway. The application note also provides power optimization techniques for XMEGA AU MCUs to reduce the overall system power consumption.