Proving the Business Case for the Internet of Things

STM combines technology to protect smart meters

Steve Rogerson
August 7, 2018

With industrial-grade longevity that assures availability for ten years, Swiss firm ST Microelectronics has combined a magnetometer and e-compass to provide tamper detection for smart meters.
The IIS2MDC magnetometer and ISM303DAC e-compass enable both reliable, low-power tamper detection for smart meters and precision motion and distance sensing in applications from industrial automation and robotics to smart buildings, smart security and medical devices.
Both sensors contain an AMR (anisotropic magneto-resistive) magnetometer with dynamic range of ±50 gauss, which meets best-in-class benchmarks for resolution and low power consumption. Each also has an integrated temperature sensor, and provides a 16bit digital output via a built-in I2C SPI serial interface.
The ISM303DAC’s additional integrated low-noise three-axis accelerometer with user-selectable full-scale range up to ±16g enables dual-mode magnetic and physical tamper detection. It also serves applications such as antenna pointing, positioning and navigation, robot guidance, and general industrial motion tracking or distance sensing. The magnetic and accelerometer blocks can be powered down independently to increase energy savings.
Both devices can be configured to generate an interrupt signal for magnetic-field detection and automatically compensate for hard-iron offsets provided from the higher application layer. Additionally, the ISM303DAC can generate interrupts upon recognition of freefall events, tap and double-tap, activity or inactivity, 6D-orientation thresholds, and wake-up events.
A built-in fifo stores accelerometer data to reduce main-processor intervention and, as a result, reduce system power consumption.
Development support includes drivers for both sensors, and software examples including tilt-compensated electronic compass, dynamic magnetometer calibration, and six- or nine-axis sensor fusion.
The Steval-MKI185V1 adapter board for the IIS2MDC and Steval-MKI184V1 for the ISM303DAC are also available, ready to plug into a standard DIL24 socket on a motherboard such as the Steval-MKI109V3 professional MEMS board to assist development using STM’s Unico gui.
The IIS2MDC and ISM303DAC are available in the leadless 2 by 2 by 0.7mm LGA-12 package, priced from $0.85 for the IIS2MDC or $1.90 for the ISM303DAC. The adapter boards are available directly from STM or from distributors, at the recommended price of $16 for the MKI185V1 or $17.15 for the MKI184V1. The SMKI109V3 main board is also available from STM or distributors, priced $85.75.