Introduction

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CircuitPython module for the MMA8451 3 axis accelerometer.

Dependencies

This driver depends on:

Please ensure all dependencies are available on the CircuitPython filesystem. This is easily achieved by downloading the Adafruit library and driver bundle.

Usage Example

See examples/simpletest.py for a demo of the usage.

Contributing

Contributions are welcome! Please read our Code of Conduct before contributing to help this project stay welcoming.

Building locally

Zip release files

To build this library locally you’ll need to install the circuitpython-build-tools package.

python3 -m venv .env
source .env/bin/activate
pip install circuitpython-build-tools

Once installed, make sure you are in the virtual environment:

source .env/bin/activate

Then run the build:

circuitpython-build-bundles --filename_prefix adafruit-circuitpython-mma8451 --library_location .

Sphinx documentation

Sphinx is used to build the documentation based on rST files and comments in the code. First, install dependencies (feel free to reuse the virtual environment from above):

python3 -m venv .env
source .env/bin/activate
pip install Sphinx sphinx-rtd-theme

Now, once you have the virtual environment activated:

cd docs
sphinx-build -E -W -b html . _build/html

This will output the documentation to docs/_build/html. Open the index.html in your browser to view them. It will also (due to -W) error out on any warning like Travis will. This is a good way to locally verify it will pass.

Table of Contents

Simple test

Ensure your device works with this simple test.

examples/simpletest.py
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# Simple demo of reading the MMA8451 orientation every second.
# Author: Tony DiCola
import time

import board
import busio

import adafruit_mma8451


# Initialize I2C bus.
i2c = busio.I2C(board.SCL, board.SDA)

# Initialize MMA8451 module.
sensor = adafruit_mma8451.MMA8451(i2c)
# Optionally change the address if it's not the default:
#sensor = adafruit_mma8451.MMA8451(i2c, address=0x1C)

# Optionally change the range from its default of +/-4G:
#sensor.range = adafruit_mma8451.RANGE_2G  # +/- 2G
#sensor.range = adafruit_mma8451.RANGE_4G  # +/- 4G (default)
#sensor.range = adafruit_mma8451.RANGE_8G  # +/- 8G

# Optionally change the data rate from its default of 800hz:
#sensor.data_rate = adafruit_mma8451.DATARATE_800HZ  #  800Hz (default)
#sensor.data_rate = adafruit_mma8451.DATARATE_400HZ  #  400Hz
#sensor.data_rate = adafruit_mma8451.DATARATE_200HZ  #  200Hz
#sensor.data_rate = adafruit_mma8451.DATARATE_100HZ  #  100Hz
#sensor.data_rate = adafruit_mma8451.DATARATE_50HZ   #   50Hz
#sensor.data_rate = adafruit_mma8451.DATARATE_12_5HZ # 12.5Hz
#sensor.data_rate = adafruit_mma8451.DATARATE_6_25HZ # 6.25Hz
#sensor.data_rate = adafruit_mma8451.DATARATE_1_56HZ # 1.56Hz

# Main loop to print the acceleration and orientation every second.
while True:
    x, y, z = sensor.acceleration
    print('Acceleration: x={0:0.3f}m/s^2 y={1:0.3f}m/s^2 z={2:0.3f}m/s^2'.format(x, y, z))
    orientation = sensor.orientation
    # Orientation is one of these values:
    #  - PL_PUF: Portrait, up, front
    #  - PL_PUB: Portrait, up, back
    #  - PL_PDF: Portrait, down, front
    #  - PL_PDB: Portrait, down, back
    #  - PL_LRF: Landscape, right, front
    #  - PL_LRB: Landscape, right, back
    #  - PL_LLF: Landscape, left, front
    #  - PL_LLB: Landscape, left, back
    print('Orientation: ', end='')
    if orientation == adafruit_mma8451.PL_PUF:
        print('Portrait, up, front')
    elif orientation == adafruit_mma8451.PL_PUB:
        print('Portrait, up, back')
    elif orientation == adafruit_mma8451.PL_PDF:
        print('Portrait, down, front')
    elif orientation == adafruit_mma8451.PL_PDB:
        print('Portrait, down, back')
    elif orientation == adafruit_mma8451.PL_LRF:
        print('Landscape, right, front')
    elif orientation == adafruit_mma8451.PL_LRB:
        print('Landscape, right, back')
    elif orientation == adafruit_mma8451.PL_LLF:
        print('Landscape, left, front')
    elif orientation == adafruit_mma8451.PL_LLB:
        print('Landscape, left, back')
    time.sleep(1.0)

adafruit_mma8451

CircuitPython module for the MMA8451 3 axis accelerometer. See examples/simpletest.py for a demo of the usage.

  • Author(s): Tony DiCola
class adafruit_mma8451.MMA8451(i2c, *, address=29)

MMA8451 accelerometer. Create an instance by specifying: - i2c: The I2C bus connected to the sensor.

Optionally specify: - address: The I2C address of the sensor if not the default of 0x1D.

acceleration

Get the acceleration measured by the sensor. Will return a 3-tuple of X, Y, Z axis acceleration values in m/s^2.

data_rate

Get and set the data rate of the sensor. Must be a value of: - DATARATE_800HZ: 800Hz (the default) - DATARATE_400HZ: 400Hz - DATARATE_200HZ: 200Hz - DATARATE_100HZ: 100Hz - DATARATE_50HZ: 50Hz - DATARATE_12_5HZ: 12.5Hz - DATARATE_6_25HZ: 6.25Hz - DATARATE_1_56HZ: 1.56Hz

orientation

Get the orientation of the MMA8451. Will return a value of: - PL_PUF: Portrait, up, front - PL_PUB: Portrait, up, back - PL_PDF: Portrait, down, front - PL_PDB: Portrait, down, back - PL_LRF: Landscape, right, front - PL_LRB: Landscape, right, back - PL_LLF: Landscape, left, front - PL_LLB: Landscape, left, back

range

Get and set the range of the sensor. Must be a value of: - RANGE_8G: +/- 8g - RANGE_4G: +/- 4g (the default) - RANGE_2G: +/- 2g

Indices and tables