The French electronics engineering firm Nemeus has created an ultra-low-power collar-mounted sensor for monitoring livestock, built around Nordic Semiconductor‘s nRF52840 multiprotocol System-on-Chip. Fastened around the neck of grazing animals, the collar device carries out motion and temperature sensing to identify key events tied to the animal’s well-being. Warnings are then sent wirelessly to the farmer, enabling them to keep track of the herd’s health and comfort through a smartphone or web application.
Bluetooth LE for short-range data transfer
Built for a client specializing in agricultural sensing technology, the collar device transmits sensor readings over long distances using LoRaWAN, while leveraging the Bluetooth LE connectivity of the nRF52840 SoC for short-range interactions — including device configuration, firmware updates, and status checks directly from a smartphone. The collar can supply farmers with actionable insights for managing their herd, such as estrus cycle detection, calving events, feeding patterns, and health and comfort metrics like lying, standing, and resting durations.
Nemeus handled the complete hardware and firmware design of the collar, and oversaw end-to-end production in collaboration with an electronics manufacturing services (EMS) partner. The company established the end-of-line testing procedures and built the full supporting toolchain — including test firmware, production test software, barcode scanner integration, and a test server with quality data logging.
“Throughout development, the overriding constraint was power consumption,” says Gilles Ronco, president of Nemeus. “The device needs to operate on a single primary cell for years across a broad temperature range, and must handle peak current draws during LoRaWAN transmissions without draining the overall energy budget. Every design choice — quiescent current, radio duty cycling, sleep strategy — was driven by that priority.”
“Beyond power, bill-of-materials cost and software complexity were just as important. We needed to combine Bluetooth LE and LoRaWAN communications on a single programmable microcontroller. Using two separate chips — one running a Bluetooth LE stack and another running the application and LoRaWAN stack — would have raised the BOM cost, introduced inter-processor communication overhead, and made firmware management considerably more complicated, especially for dual-MCU over-the-air updates that demand larger Flash storage.”
Lower power draw and reduced BOM
To hit its power targets while cutting BOM costs and software complexity, Nemeus chose the nRF52840 SoC. The design goal is multi-year battery life from a single primary cell, and the nRF52840’s built-in DC/DC converter, deep sleep modes, and overall power management architecture were a natural fit for a device whose power profile is dominated by low quiescent draw punctuated by periodic high-current LoRa transmission bursts.
The Nordic SoC also manages the Bluetooth LE protocol alongside application logic, while an external LoRa transceiver handles the sub-GHz radio. According to Nemeus, shifting from a dual-MCU architecture to a single nRF52840 SoC removed the need for an inter-processor communication bus, eliminated redundant crystal oscillators, reduced both PCB complexity and Flash memory requirements, and streamlined the entire firmware build and update pipeline.
Beyond the simpler hardware architecture, the Nordic SoC made large-scale field firmware updates possible through Nemeus’ proprietary Bluetooth LE DFU propagation system. This mechanism lets a farmer update a single collar on one animal from their phone via Bluetooth LE, after which the new firmware spreads to other collars over Bluetooth LE. Multiple updated devices can serve as sources at the same time, speeding up propagation and enabling every collar across an entire herd to be updated within minutes to hours depending on the size of the operation. The propagation framework is layered on top of Zephyr’s standard DFU stack, augmented with Nemeus’ ultra-low-power advertising and scanning logic so that propagation has a negligible effect on battery life.
“Compared with other chip vendors, Nordic excels in two critical areas: the quality of their products and the quality of their support,” Ronco adds. “Their engineers are directly reachable when needed, which is uncommon at this scale and fosters a lasting relationship built on trust.”
“The customer had demanding timeline requirements, and this project became one of the fastest we’ve taken from development through to mass production. Selecting a chip we knew inside and out was as much a risk-management decision as a technical one. The nRF52840, combined with our existing Nemeus codebase on the nRF Connect SDK and Zephyr, gave us the confidence that we could deliver.”
Comment on this article via X: @IoTNow_ and visit our homepage IoT Now
