Data Sheet

ManualsBrandsDevantech ManualsMagnetic Sensors / CompassTilt Compensated Magnetic Compass (CMPS12)

CMPS12 – documentation

Introduction

The CMPS12 is our 4th generation tilt compensated compass. Employing a 3-axis magnetometer, a 3-

axis gyro and a 3-axis accelerometer. At the core of the module is the superb BNO055 running

algorithms to remove the errors caused by tilting of the PCB.

Power supply requirements are flexible, you can feed between 3.3 - 5v and the module draws a nominal

18mA of current. A choice of serial or I2C interfaces can be used for communication.

Overview of outputs

Heading, 16 bit – 2 outputs, one calculated by Bosch and one by us

Heading, 8 bit – 0-255 scaled for simpler requirements

Pitch – +/- 0-90° or +/- 0-180°

Roll – +/- 0-90°

Temperature – current temperature of the BNO055 in °c

Raw sensor outputs – 3 x 16 bit integers for each of the Magnetometer, accelerometer and gyro

Mode selection

Serial or I2C mode is easily selected with the state of the mode pin. Note the CMPS12 looks at the

mode selection pin at power-up only.

3.3v-5v

SDA/TX

SCL/RX

Mode

Factory use

0v ground

For I2C the mode pin can be left open or pulled to the supply voltage, for serial mode the mode pin

should be connected to 0v ground.

Summary of content (6 pages)

PAGE 1
CMPS12 – documentation Introduction The CMPS12 is our 4th generation tilt compensated compass. Employing a 3-axis magnetometer, a 3axis gyro and a 3-axis accelerometer. At the core of the module is the superb BNO055 running algorithms to remove the errors caused by tilting of the PCB. Power supply requirements are flexible, you can feed between 3.3 - 5v and the module draws a nominal 18mA of current. A choice of serial or I2C interfaces can be used for communication.
PAGE 2
I2C Mode The compass has a 31 byte array of registers: Register Function 0 Command register (write) / Software version (read) 1 Compass Bearing 8 bit, i.e. 0-255 for a full circle Compass Bearing 16 bit, i.e. 0-3599, representing 0-359.9 degrees. register 2 being the 2,3 high byte.
PAGE 3
In register 25 the temperature that the BNO055 is currently measuring is provided in °C. Bosch generate a compass bearing within the BNO055, so this is available in registers 26 (high byte) and 27 (low byte) and together they form a 16 bit unsigned integer in the range 0-5759, this number can be scaled to degrees by dividing by 16. Registers 28 (high byte) and 29 (low byte) form a 16 bit pitch angle for +/- 180 from the horizontal plane.
PAGE 4
Serial mode Communication settings The Serial mode operates over a link with a default baud rate of 9600 bps (no parity, 2 stop bits) and 3.3v-5v signal levels. This is not RS232. Do not connect RS232 to the module, the high RS232 voltages will irreversibly damage the module.
PAGE 5
Calibration of the CMPS12 The CMPS12 is automatically calibrated by movement, there is no instigation required by the user. The level to which the CMPS12 has been calibrated can be checked by using command 0x24, bits 0 and 1 of the response byte will start at 0 (xxxxxx00 un-calibrated) and increase to 3 (xxxxxx11) with calibration. Storing and erasing calibration profiles After calibrating the compass the profile can be stored so it will be automatically reloaded when the module is ready for use again.
PAGE 6
Migration from the CMPS11 Every effort has been made to try and make the CMPS12 as compatible with its CMPS11 predecessor. Electronically it has been designed to drop in with pin compatibility. In I2C mode all data is in the same locations as it was found on the CMPS11 with some extra features in new registers, in serial mode the original command set is implemented and added to for some extra features.