SparkFun 9DoF IMU Breakout - IM19

The SparkFun 9DoF IMU Breakout with the FMI IM19 is a precision tool designed for high-accuracy positioning, navigation, and timing (PNT) projects. It combines advanced MEMS sensor data with external GNSS RTK positioning information to deliver precise attitude measurements and tilt compensation. This sensor fusion capability is exclusive to RTK GNSS receivers, requiring an "RTK Fix" status for optimal operation.

In practical applications, this IMU excels in scenarios demanding survey-grade accuracy. When paired with a compatible RTK setup, it provides roll and pitch measurements accurate to within 0.05 degrees. This precision enables tilt-compensated surveying, allowing for faster field data collection without the need for perfectly vertical survey poles. It also supports continuous Dead Reckoning navigation, maintaining reliable navigation even when GNSS signals are temporarily lost, making it ideal for urban or obstructed environments.

To begin using the IM19, input NMEA GGA, GST, and RMC messages at 5Hz, along with a standard Pulse-Per-Second (PPS) timing signal. The board outputs a proprietary NMEA ASCII GPFMI message, which includes the compensated position of your survey pole's tip, along with the precise roll, pitch, and yaw of the IMU.

The hardware design is user-friendly and modular, offering flexible access to the IM19's UART interfaces. The dual USB-UART interface, locking JST connection, and breadboard prototyping options cater to various build requirements. Power the board via USB, the 5V VIN pad, or an external 3.3V supply. Its 4.3 cm x 4.3 cm PCB footprint aligns with standard RTK GNSS boards, facilitating easy stacking with existing receivers. The IM19 chip's central placement simplifies LEVER_ARM calculations, with a Z-origin of 1.6 mm above the top surface and 3.2 mm above the bottom surface.