Compass module

Possible new version Readout I2C 6 axis Accuracy 1-2 degrees 3 magnetic 3 accelerometer Accuracy 1-2 degrees PMT size 72 mm at 212 mm is 330 mrad Accuracy of compass 1/10  33 mrad = 1.9 degrees

Many chips available Robotics and mobile telephone have made chips cheap and low power in the past years Chips are readily available most have gyroscope also. Some easily available models are MPU-925x (includes a secondary I2C bus and DMP) www.invensense.com LSM9DS1 (9d) , LSM303D (6d) simple readout via I2C of axis values www.st.com Power consumption: Magnetic sensor setting ODR = 6.25 Hz, accelerometer sensor ODR = 50 Hz and magnetic high-resolution setting: 300 mA @ 3.3V = 1mW.

STMicroelectronics

Tests Test done with the LSM9DS1 on breakout board from Sparkfun. Calibration: measurement in six orientations of acceleration and magnetic field to determine zero offsets.

Tests Installed on CLB Read out through I2C bus Stable within 0.5 degrees Operates in any orientation Z-axis accelerometer offset by 0.5 g Absolute pointing (comparison to normal magnetic compass equal within measurement accuracy)

Setup

Pin compatible PCB A PCB has been designed for the LSM303D Requires Footprint of LSM303D and 2 capacitors and 2 pull up resistors Axes are equal to AHRS Will be delivered most likely on Friday Feb 5 (€2500 for 100 items, speed delivery). Will be tested and calibrated “off-line” If all OK build it into a DOM and fully test it.

Conclusions Next week we will (probably) have a pin compatible compass board. Cost around €25 (full production ~ € 10) Power consumption 1 mW. For future could place it directly on the CLB