Usage

Sample code

The following code initializes the sensor, and prints the magnetic field values for x, y and z. Then, using the atan2 function from the math standard library, it retrieves the heading of the sensor.

import bmm150
import math

device = bmm150.BMM150()

x, y, z = device.read_mag_data()

heading_rads = math.atan2(x, y)

heading_degrees = math.degrees(heading_rads)

print(f"X : {x:.2f}µT")
print(f"Y : {y:.2f}µT")
print(f"Z : {z:.2f}µT")

print(f"Heading: {heading_degs:.2f}°")

Presets

The bmm150 sensor provides 4 different presets, offering a trade between accuracy and power consumption. The more accuracy is required, the more measures will be made, thus the more the power consumption will raise.

On each preset, n measures will be taken and averaged out, noted by the number of repetitions (Rep X/Y for the X and Y axis, Rep Z for the Z axis). The Recommended ODR (Output Data Rate) indicates the rate at which the data might be polled for optimal results.

The presets are detailed in the following table:

Preset	Rep. X/Y	Rep. Z	Recommended ODR
Low power preset	3	3	10
Regular preset	9	15	10
Enhanced regular preset	15	27	10
High accuracy preset	47	83	20

A preset can be specified when instantiating a BMM150.

import bmm150

device = bmm150.BMM150(presetmode = bmm150.PresetMode.LOWPOWER)
device = bmm150.BMM150(presetmode = bmm150.PresetMode.REGULAR)
device = bmm150.BMM150(presetmode = bmm150.PresetMode.HIGHACCURACY)
device = bmm150.BMM150(presetmode = bmm150.PresetMode.ENHANCED)