What is it?

This is Invensense's new ITG3701 MEMS gyro with an industry beating +/-4000 degrees per second full-scale range coupled with ST Microelectronics' LSM303D e-compass (accelerometer + magnetometer) and Measurement Specialties' 24-bit MS5637 pressure/temperature sensor. The combination is packaged on a small add-on board that can be mounted directly onto the Teensy 3.1 Cortex M4 ARM microprocessor or, by using the solder jumpers on the back to take power and ground from the board edge, can be used as a conventional breakout board for breadboarding with an Arduino. The board uses I2C communication only, and has a solder jumper on the front to allow the use of the 4K7 I2C pullup resistors if there are not already pullups in the circuit. There is one interrupt broken out for each of the three motion sensors (not for the pressure sensor) and the gyro has an additional pin broken out for syncing with an external source such as a camera, GPS, etc. The sensors are 3V3 only and a logic level converter should be used for higher voltages.

Why did you make it?

There are many choices for MEMS gyros either stand alone or integrated with other motions sensors. To my knowledge, this is the only gyro that has a full-scale range as high as 4000 degrees per second, all of the other ones stop at 2000 degrees per second (the SENtral breakout board returns gyro rotation rates with a full-scale of +/- 5000 dps, but the underlying BMX055 gyro sensor is rated to only +/- 2000 dps max, not sure how this works other than through the ADC). This means that you can track rotary motions up to 11 Hz, or 650 rpm, which translates roughly to 35 miles per hour on a bicycle wheel. This allows characterization of motion during vigorous human or animal action like extreme sports, racing, etc. that conventional gyros cannot manage. I chose to couple this unique gyro capability with the LSM303D accelerometer/magnetometer because this sensor also offers high accelerations (up to 16 g) and magnetic fields (up to 12 Gauss); it is the same accel/mag used in the LSM9DS0 and has proven highly reliable and stable. Rounding out the sensor suite with the MS5637 altimeter provides a motion sensor with 10 degrees of freedom able to track the most extreme human activity.

What makes it special?

This breakout board packs a lot of functionality in a small space. It is ideally used by mounting directly on a Teensy 3.1 allowing a very small footprint for portable or wearable applications. With the addition of other add-ons (e.g., LiPo Battery Charger, 512 kByte EEPROM, 2.4 GHz radio) you can tailor a multifunction device that suits your specific application.

I have written a sketch that configures and calibrates the sensors, gets scaled pressure, temperature, accelerations, rotation rates, and magnetic fields, and performs 9 D0F sensor fusion using open-source Madgwick and Mahony algorithms.

Order the board from OSH Park and assemble your own or buy the fully assembled and tested board from me and see if this high-rate motion sensor solution is right for your application!