What is it?

ST Microelectronics' new high-g accelerometer.

From ST's product page: The H3LIS331DL is a low-power, high-performance 3-axis linear accelerometer belonging to the “nano” family, with digital I2C/SPI serial interface standard output. The device features ultra-low power operational modes that allow advanced power saving and smart sleep-to-wakeup functions. The H3LIS331DL has dynamically user-selectable full scales of ±100 g/±200g/±400g and it is capable of measuring accelerations with 16-bit resolution with output data rates from 0.5 Hz to 1 kHz. The H3LIS331DL is available in a small thin plastic land grid array package (LGA) and it is guaranteed to operate over an extended temperature range from -40 °C to +85 °C

This is a very small breakout board hardwired for I2C with both interrupts broken out to allow the embedded wake-on-motion feature as well as interrupt on acceleration thresholds to be conveniently used. There are on-board 4K7 pullups on the I2C SDA and SCL lines. This board is intended either for breadboard use or, more likely, monitoring some object being subjected to a sharp impact or other large acceleration. It is easy to connect wires to this board and its small size means it can be easily attached to many objects of interest including vehicles, sports equipment (balls, bats, helmets, etc.) or even parts of the body subject to sudden impacts.

Why did you make it?

Like the high-rotation rate gyros made by Invensense and offered for sale at Tindie, there are many motion sensing tasks beyond the range of conventional MEMS motion sensors. Specialty motion sensors like the H3LIS331D intended to measure very high accelerations can meet the needs of those interested in measuring or monitoring performance in harsh environments.

Sports applications include concussion detection and measuring (soccer, baseball) ball accelerations; other obvious applications include measuring car crash dynamics etc. Any large-force accelerations beyond the range (>16 g) of typical MEMS accelerometers can be measured accurately with this special hi-g accelerometer.

I wrote a basic sketch that runs on a Teensy 3.1 or Arduino Pro Mini to initialize the sensor, calibrate out the acceleration biases, and get properly scaled accelerations out. The jitter in the measured accelerations at rest is about 0.1 g at +/- 100 g full scale; this is a pretty good (~0.1%) noise floor allowing the measurement of accelerations in the tens of gs with high accuracy.

What makes it special?

This is a very small board making it possible to monitor small objects subject to harsh environments. Order the board from OSH Park and build your own, or order the fully assembled and tested board from me and see how rough and tumble your application can get!