Viable asset tracking solutions must overcome several design challenges associated with sensing, storing and transmitting appropriate data on limited power budgets using very compact and inexpensive hardware. This battery-powered asset tracking solution combines a suite of digital sensors, a very low power STM32 microcontroller, and Bluetooth module with power management circuitry to allow comprehensive environmental, orientation and motion monitoring over extended storage and shipping intervals.
For environmental conditions, the low power STM32L4 MCU monitors the data from separate digital MEMS temperature, humidity and pressure sensors at set intervals to trigger actions such as enabling de-humidification systems in containers when humidity thresholds are exceeded or disabling radio transmission when altitude variations detected by pressure sensors are consistent with an airplane taking off. The MCU can similarly monitor accelerometer data to record motion, orientation, vibration, impact and freefall events, and latest generation sensors with machine learning cores offer far better power management and improved accuracy to monitor even the most complex motions of vehicles, ships and aircraft.
The MCU stores the tracking data on removable memory, which can be accessed by an authorized smartphone application via the Bluetooth module with application processor. The module also allows the app to configure relevant asset tracking parameters on the MCU, such as critical thresholds and logging frequencies according to user and application requirements. The data on the smartphone can be analyzed immediately or forwarded to a centralized server or cloud service for widescale processing and analysis.
Power circuitry for USB battery charging and fine power management, along with appropriate shutdown and restart protections in case of faults complete the design.
BlueNRG-M2 BLE 5.2 module
This certified module delivers high wireless connectivity range, performance and security according to the Bluetooth Low Energy 5.2 specification, with application processor allowing device configuration and access to stored sensor data without MCU intervention.
STM32L4+ Series MCU
This ultra-low-power microcontroller is highly suited to battery-powered applications with the power management and-performance of an Arm® Cortex®-M4 32-bit RISC core, and appropriate clock speed and set of interface peripherals to manage simultaneous data from various sensors.
LIS2DW12 - high perfromance 3 -axis accelerometer
This ultra-low-power, high-accuracy, three-axis linear accelerometer is well suited for tracking the movement of assets and registering sharp acceleration events such as falling, sliding, and impacts in a power constrained solution.
LSM6DSOX - low power inertial sensor
This iNEMO 6DoF inertial module provides object motion and rotation data, and features a Machine Learning Core, Finite State Machine and advanced digital functionality allowing the immediate detection of significant events in order to trigger appropriate MCU responses.
HTS221 - high accuracy humidity sensor
This high accuracy sensor gathers humidity and temperature data for asset tracking applications and allows critical threshold values to be monitored, which is especially important in applications such as cold chain shipments.
LPS22HH - high accuracy barometer
This ultra-compact piezo-resistive absolute pressure sensor functions as a digital output barometer in the 260-1260 hPa range, which is even suitable for detecting sharp changes in elevation, such as when a plane is taking off or landing.
STBC02 - Li-Ion battery charger
Li-Ion linear battery charger with LDO, load switches and reset generator.
- Application is Running on Cortex-M4 core features a single-precision floating-point unit (FPU) and implements a full set of DSP (digital signal processing) instructions and a memory protection unit (MPU) which enhances the application’s security.
- High levels of device integration, miniaturization and ultra-low power consumption render the nodes compact and portable with extended battery lifetime.
- Flexibility to change duty cycle and sensor parameters stored in the memory, and threshold settings to wake-up the system using an appropriate app on an BLE-enabled mobile device.
- MEMS environmental and motion sensors provide highly accurate data for asset tracking scenarios such as cold chain applications, Humidity accuracy: ±3.5%RH and temperature accuracy with 0.5%
- On board there is a system-in-package featuring, a 3D digital accelerometer and a 3D digital gyroscope, with Machine Learning Core, Finite State Machine and advanced Digital Functions, boosting performance at 0.55 mA in high-performance mode and enabling always-on low-power features for an optimal motion experience for the consumer.
- On the board also the Analog components are ST products: as the battery charger and management and the power conversion to supply the different elements on the boards. Plus, the signal condition as OpAmps and comparators and multiple ESD protections.