What is it?

This is a small (0.6" x 0.3") add-on for the Ladybug (STM32L432) Development Board with Invensense's MPU9250 accelerometer/gyro/magnetometer 9 DoF motion sensor and Bosch's BME280 pressure/humidity/temperature sensor. The board is designed to mount directly onto the non-USB end of the Ladybug using the I2C port and the 3V3 and GND ports at the end of the board. You can solder the add-on to the top or bottom of the Ladybug for a permanent installation or use machine pin headers so you can remove the board and replace with some other add on as the need requires.

The combination add-on has the MPU9250 interrupt broken out on Ladybug pin 10 which conflicts with the SPI flash add-on chip select, so in order to be able to use the MPU9250 and SPI flash add-ons together, I designed a larger MPU9250-only add-on without the BME280 (not everyine wants a pressure.humidity/temperature sensor witht their IMU) that puts the MPU9250 interrupt on pin 9 so deconflicting the SPI flash from the MPU9250 add-on. This is usful if you want to log orientation or accel/gyro data from the MPU9250 using the SPI flash memory add-on. It is also a less expensive way to add an great IMU to your Ladybug!

Why did you make it?

Ladybug is a small STM32L432 development board and I wanted to be able to use a full range of sensors in a form factor easy to mount directly onto the Ladybug for compact, battery-powered solutions to sensing and data logging problems. In this case, the MPU9250+BME280 add-on in combination with open-source sensor fusion algorithms can be used to measure orientation and altitude making the combination useful for motion control applications like rocket telemetry, quadcopter control, inclination sensors, etc. The super small Ladybug+sensor-add-on+battery package means such solutions can fit practically anywhere!

What makes it special?

This is a small add-on board specifically designed to mount directly onto the Ladybug development board. There is an Arduino sketch written for this add-on allowing you to get the most out of these sensors using the Arduino IDE.

Order the pcb from OSH Park and assemble some of your own, or buy the assembled and tested add-on board here and see what motion sensing in a very small package can do for your applications!